Search

The heterogeneous phase reaction of Rh(MeLsb)(PPh3)2Cl2 (1) with the sodium salt of three differently substituted picolinate ligands [Na(R-pic), R = H, Me, Cl] in dichloromethane–acetone–water medium afforded the complexes of the type Rh(Lal)(PPh3)2(R-pic) (2(R)) in excellent yield. These are the first examples of acylrhodium(III) complexes with the picolinate ligand. The chelation of the picolinate ligand is attended with the cleavage of the two Rh Cl bonds and concomitant hydrolysis of the aldiminium function in 1. The picolinate ligand is coordinated to the rhodium center as bidentate N,O-donor forming five-membered chelate ring. The spectral (UV–Vis, IR, NMR) and electrochemical data of the complexes are reported. The identity of 2(H) has been established by single-crystal X-ray structure determination which revealed distorted octahedral RhCNO2P2 coordination sphere. The pairs (P,P), (C,O) and (O,N) define the three trans directions. The electronic structures and the absorption spectra of the complexes are also scrutinized by the density functional theory (DFT) and time-dependent DFT analysis.

Reaction of 2,6-diformyl-4-methylphenol, 1,3-diaminopropane, Mn(ClO4)2∙6H2O and CH3COONa∙3H2O in 1:1:1:1 mole ratio in methanol afford a linear coordination polymer of formula {[MnIIMnIIIL(OAc)2]ClO4}n (L2− represents the Robson-type ligand) in 64% yield. The complex has been characterized by elemental (CHN) analysis, magnetic susceptibility, spectroscopic (IR, UV–Vis and EPR) and solution electrical conductivity measurements. The linear polymeric structure and the mixed-valent character of the complex have been confirmed by single crystal X-ray crystallography. In the repetitive dinuclear unit, both metal centers are in N2O4 coordination spheres assembled by the compartmental macrocyclic N2O2N2-donor L2−, an intra-dinuclear bridging acetate and an inter-dinuclear bridging acetate. The coordination geometry around the manganese(II) center (S = 5/2) is severely distorted octahedral, while that around the manganese(III) center (S = 2) is tetragonally elongated octahedral. Variable temperature magnetic susceptibility measurements indicate a weak intra-dinuclear ferromagnetic (J = 1.12(3) cm−1) interaction as well as a weak inter-molecular antiferromagnetic (zJ′ = −0.679 (3) cm−1) interaction. Cyclic voltammogram of the complex displays a metal centered quasi-reversible reduction at −0.03 V and an irreversible ligand centered reduction at −1.16 V (vs Ag/AgCl). The complex efficiently catalyzes the aerobic oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butylbenzoquinone with a turnover number (kcat) 1.2 × 104 h−1.

The trans(O5O6) isomer of the Na[Rh(eddadp)]·4H2O and the K[Co(eddadp)]·3H2O (eddadp = ethylenediamine-N,N′-diacetate-N,N′-di-3-propionate) were synthesized and Na[Rh(eddadp)]·4H2O structure was confirmed by X-ray diffraction analysis. The percentage of particular isomers found in reaction equilibrium mixtures of [M(eddadp)]− complex has been reported. Single crystal X-ray diffraction of the complex revealed an octahedral geometry of the Rh(III) centre. Improved structural distortion analysis of M(III) (M = Rh, Co) complexes with symmetric edta-type of ligands containing mixed carboxylate and diamine rings was made. Structural distortion analysis has determined high values of total deviation of the octahedral angles (Δ(Oh)) for both existing trans(O5) (34°) and trans(O5O6) (41°) isomers of [Rh(eddadp)]− complex, while in the case of a similar Co(III) complex, relatively low value (31°) for trans(O5) has been established. Extensive QM/NBO calculations were made for both systems [M(eddadp)]− and [M(1,3-pddadp)]− using different DFT methods (B3LYP/SDD, M06/SDD, MP2/SDD). By correlating the structural parameters obtained from X-ray and DFT optimized 3D structures, the B3LYP/SDD method was used as the method of choice. Based on the correlation between the energies of the optimized systems and the strain parameters, the existence of the trans(O6) isomer of the [Rh(1,3-pddadp)]− complex was predicted. NRT (Natural Resonance Theory) analysis gave the best resonances for each isomer. Here the stability of particular isomer has been described in terms of 3-CHB bonds involving metal ions and Second Order Perturbation Theory analysis using Donor/Acceptor energies. Further, to explain the bonding nature of M-edta-type complexes the Natural Coulomb Electrostatics (NCE) analysis has been done as well. The pairwise steric exchange interaction EI,Jpwx results obtained for the best-ranked resonances of different isomers are in excellent agreement with favored isomers reported so far. For the energy limit of the possibility of forming geometric isomers, a value of about 6 kcal mol−1 is proposed.

Two mixed-valence cobalt complexes, [CoIICoIII2(mpm)6](ClO4)2 (1) and [CoII2CoIII2(μ3-OMe)2(μ-mpm)4(NO3)4] (2), where mpm is the deprotonated form of R or S α-methyl-2-pyridinemethanol, have been structurally and magnetically characterized. Both complexes crystallize in chiral space groups, where 1 is a trinuclear compound with a linear Co(III)–Co(II)–Co(III) topology and 2 is a tetranuclear cluster with a defect dicubane-type structure that has two missing vertices. In both cases the mpm− ligand bridges adjacent Co ions in a η1:η2:μ manner. The molecular geometries of the complexes reveal the Co ions are octahedral, where the greatest deviation from Oh symmetry is apparent for the HS d7 Co(II) ions. The chirality of 1 and 2 were studied by circular dichroism spectroscopy where opposite Cotton effects are observed for the R- and S-enantiomers of both complexes. Magnetic susceptibility studies reveal the presence of largely quenched first order orbital angular momentum together with weak ion or intermolecular dipole exchange.

This study describes supramolecular assemblies of Cu(II) and Ni(II) 2,2′-bipyridine cations with dimeric tartratogermanate anions, namely [CuCl(bipy)2]2[Ge2(OH)2(Tart)2]·4H2O (I) and [Ni(bipy)3]4[{Ge2(OH)2(Tart)2}3Cl2]·15H2O (II). The compounds were characterized by elemental analysis, mass-spectrometry, IR-spectroscopy and X-ray analysis. The chloride ion coordinates to the Cu atom in cation I and two chloride ions together with the [Ge2(OH)2(Tart)2]2− anion neutralize the charge of the cation in II. The coordination polyhedra of the Ge atoms are trigonal bipyramids in the structures of I and II. The coordination polyhedra of two symmetrically independent [CuCl(bipy)2]1+ cations are distorted trigonal bipyramids in the structure of I, whilst the coordination polyhedra of the Ni cations in II are octahedral.

Sr2Nb10O27 and Sr2Ta10−xO27−y exhibit the tripled tetragonal-tungsten-bronze (TTTB)-related superstructures. In contrast to Sr2Ta10−xO27−y, where an extended solid solution was found, Sr2Nb10O27 only forms a narrow range of solid solution, Sr1−xNb10O27−z (0 ≤ x ≤ 0.04). Serial X-ray and neutron diffraction studies show that both compounds can be modelled in the orthorhombic Pba2 space group. Lattice parameters obtained from powder X-ray refinements are a = 12.3887(14) A, b = 37.103(4) A, c = 3.866(2) A, for Sr2Ta10−xO27−y, and a = 12.3888(2) A, b = 36.9839(5) A, and c = 3.94027(3) A for Sr2Nb10O27. Neutron Rietveld refinements of both structures revealed the possible reason for the differing solid solution behavior. For Sr2Nb10O27, all Nb sites are fully occupied, whereas in Sr2Ta10−xO27−y, three out of the nine crystallographically unique Ta sites were shown to be partially occupied. Charge adjustment is therefore possible by increasing the Sr concentration, leading to a solid solution series and smaller Ta/Sr ratio as compared to Sr2Nb10O27. In the TTTB-related structures, Nb and Ta ions both occupy octahedral and pentagonal bipyramidal coordination sites. Layers of interconnected corner-shared octahedra were found parallel to the ab plane, with 3-, 4- and 5-fold tunnels found in the structure running parallel to the c-axis. Sr ions partially fill the 4- and 5-fold tunnels.

Two new symmetrical macroacyclic Schiff base ligands, L1 and H2L2 have been prepared from the condensation of 2-((4-(2-aminobenzyl)-1,4-diazepan-1-yl)methyl) benzenamine (A) with 2-formylpyridine and 2-hydroxy-3-methoxybenzaldehyde, respectively. Metal complexes were synthesized by the reaction of the ligands with Ni(ClO4)2·6H2O, Cu(ClO4)2·6H2O, Mn(ClO4)2·6H2O and Co(ClO4)2·6H2O in methanol and the resulting products were characterized by elemental analyses, IR, ESI-MS, 1H and 13C NMR spectra and conductivity measurements. The structure of the complex [CoL2](ClO4) has also been determined by a single crystal X-ray structural analysis, showing that the Co(III) atom is in an almost regular trans-O2N4 octahedral environment, coordinated by all six donor atoms of the macroacyclic ligand. As well, the nature of metal–ligand bonding in the complexes was analyzed by NBO, EDA and EDA-NOCV analyses. The antioxidant and antibacterial activities of the synthesized compounds were in vitro screened by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and disc diffusion methods, respectively. The results reveal that the synthesized complexes possess excellent antioxidant (IC50; 0.325–1.303 mg/ml) and antibacterial activities in comparison to ascorbic acid and antibiotics as positive controls, respectively. In view of their biological activities, it is possible that these complexes may have future applications as biological agents.

Five new metal(II) dicyanamido (dca) complexes with 3-aminopyridine (py-NH2) have been synthesized, catena-[M(μ1,5-dca)2(py-NH2)2] {M = Mn (1), Cu (2), Co (3), Zn (4) and Cd (5)}, and characterized by elemental analysis, IR, UV–Vis spectroscopy, single crystal X-ray and powder diffraction, respectively. The isostructural polymeric 1D complexes feature double µ1,5-bridging dicyanamide ligands and two terminal 3-aminopyridine ligands located in a trans-conformation around the distorted M(II) octahedra, which add extra stability through their involvements in the formation of 3D supramolecular hydrogen bonded systems and the constitution of non-covalent π–π ring-ring interactions along the chain direction. The magnetic properties of complexes 1–3 were studied at variable temperature over the range 2–300 K. Luminescence enhancements upon complexation of dca ligands was observed in 4 and 5.

One-dimensional copper(II) coordination polymer of [Cu(TDC)(H2O)2]·H2O (1) has been synthesized and characterized by elemental analysis, X-ray diffraction and thermal gravimetric analysis. 1 consists of [Cu(µ2-H2O)2]2+ chains with decorative TDC bridges, in which the coordination polyhedron of copper(II) center is distorted octahedral. The antimicrobial activity of 1 against Gram-positive bacteria, Staphylococcus aureus (S. aureus) and Gram-negative bacteria, Escherichia coli (E. coli) was investigated by determining the minimal inhibitory concentration (MIC), the growth curve of bacteria and bacterial reduction assay, and the results indicated that compound 1 possesses higher performance compared with commercial copper nanoparticles and H2TDC. The bacteriostatic rate is up to 99.9% against both E. coli and S. aureus when the concentration of compound 1 is upon 300 µg/mL. The study on antibacterial mechanism showed that the compound 1 favors a slow release of Cu2+ ions and generation of destructive reactive oxygen species leading to excellent and long-term antimicrobial activities.

Two new oxidovanadium(V) complexes, [VOLL1] and [VOLL2], where L is the dianionic form of N′-(3-ethoxy-2-hydroxybenzylidene)-3-methylbenzohydrazide (H2L), L1 is maltolatel, and L2 is ethylmaltolate, have been prepared. Both H2L and the complexes have been characterized by elemental analysis, IR, UV–Vis and NMR spectra. The structures of the compounds were further confirmed by single crystal X-ray diffraction. The aroylhydrazone ligand coordinates to the V atoms through the phenolate oxygen, imino nitrogen and enolate oxygen. The maltolate and ethylmaltolate ligands coordinated to the V atoms through the carbonyl oxygen and deprotonated hydroxyl oxygen. The V atom in each complex is in octahedral coordination. The complexes were administered intragastrically to both normal and alloxan-diabetic mice. The biological activity results show that the complexes at doses of 10.0 and 20.0 mg V·kg−1, can significantly decrease the blood glucose level in alloxan-diabetic mice, but the blood glucose level in the treated normal mice was not altered.

Reactions of [{Re6Q8}Br6]4−/3− (Q = S, Se) with molten imidazole lead to the formation of two new neutral cluster complexes [{Re6Q8}(imzH)4(imz)2] (imzH = imidazole). The interaction of [{Re6Q8}(imzH)4(imz)2] with hydrohalic acids resulted in cationic complexes [{Re6Q8}(imzH)6]X2 (X = Cl, Br). All compounds were characterised by X-ray single-crystal and powder diffraction analyses, elemental analysis, energy dispersive X-ray and IR spectroscopies. The luminescence of the neutral compounds [{Re6Q8}(imzH)4(imz)2] was also studied.

The purpose of our research was to obtain and characterize Cu(II), Co(II) and Ni(II) complexes with herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA). The structural characterization of compounds in their powder form was based on various laboratory as well as synchrotron X-ray spectroscopic methods, magnetic measurements and atomistic calculations. The anhydrous [Cu(MCPA)2]n complex exhibits a distorted square-planar geometry. [Co(MCPA)2(H2O)4]·H2O and [Ni(MCPA)2(H2O)4]·H2O complexes have octahedral molecular geometry with two MCPA anions acting as monodentate ligands. The X-ray crystal structure analysis performed for Cu(II) complex after its recrystallization from N,N-dimethylformamide solution showed the formation of dinuclear complex with solvent molecules included in the coordination sphere of Cu(II). MCPA herbicide and its Cu(II), Co(II) and Ni(II) complexes showed the low cytotoxicity potential against HaCaT and V79 cells with IC50 in the range from 65 to >100 µM.

The two dinuclear complexes with octahedral metal centres, [Co2L(H2O)3Cl3]Cl (1) and [Ni2L(H2O)4Cl2]Cl2 (2), of the s-triazine-based di-compartmental ligand L were synthesized and characterized using single crystal X-ray diffraction (SC-XRD). The ligand L acts as a tridentate NNN-chelate with a pyrimidine-like coordinative behavior. The coordination of L was found to depend on the size of metal ion. Hirshfeld analysis indicated that the molecular packing of the studied complexes is controlled mainly by polar Cl⋯H and O⋯H contacts. The Cl⋯H interactions represent about one quarter of all the observed contacts in complexes 1 (25.4%) and 2 (31.0%), while the less important O⋯H interactions comprise 6.4 and 6.6% from the whole intermolecular interactions, respectively. The relative stability of the different conformers of L was investigated using different DFT methods and the different conversion reactions between them were analyzed using QST2 calculations.

Three mono and binuclear cadmium and mercury complexes of 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (dppt) formulated as Cd(dppt)2X2 (X = Br, I) (complexes: 1 and 2) and Hg2(dppt)2Cl2(complex: 3) were synthesized and characterized by physical and spectral (IR, 1H and 13C NMR) analyses. Moreover, structural analyses of these complexes were investigated by single crystal X-ray diffraction method. The complex 1 and 2 crystallize in the orthorhombic crystal system with space groups of Pna21, and Pbca respectively while the complex 3 crystallizes in monoclinic crystal system with space group P21/n. In all the complexes, the dppt ligand is coordinated via its N atoms of pyridyl and triazine rings to metal ion. In each cadmium complex, in addition to two bonded dppt ligands, the coordination sphere is completed by two halide anions and therefore the geometry around metal can be described as distorted octahedral. In spite of mononuclear cadmium complexes, the mercury compound is found as a centro-symmetric dimer complex including two Hg-Cl-Hg bridges, a terminal chloride and a dppt ligand on each mercury center. In this way, a distorted square pyramidal structure can be defined for the geometry around each mercury center.

Co(II) and Cu(II) complexes with distorted octahedral and distorted square planar geometries of the type [Co(L2)2(H2O)2](NO3)2 and [Cu(L1)2Cl2] have been prepared and characterized using elemental analysis, IR and crystal X-ray studies. The two complexes were prepared with two novel formamidine ligands, N′-(benzothiazol-2-yl)-N,N-dimethylformamidine (L1) and N-(pyridin-2-yl)formamidine (L2). [Cu(L1)2Cl2] crystallized in the space group P21/c, a = 8.5987(3) A, b = 15.9778(6) A, c = 10.6308(7) A, V = 1321.07(11) A3, Z = 4. [Co(L2)2(H2O)2](NO3)2 crystallized in the space group P21/c, a = 7.9187(2) A, b = 10.8117(4) A, c = 11.6687(5) A, V = 902.13(6) A3, Z = 4. The existence of H-bonding in the complex [Co(L2)2(H2O)2](NO3)2 is discussed. The negative values of the electronic energies (−2329.59 to −4461.21 a.u.), the highest occupied molecular orbital energies (−0.2311 to −0.2590 a.u.) and the lowest unoccupied molecular orbital energies (−0.063 to −0.08525 a.u.) of the complexes indicate the stability of the complexes. The complexes have noticeable cytotoxicity with IC50 (µmole/well) values of 0.002 and 0.047 (MCF-7), 0.0048 and 0.051 (HCT-116), 0.0014 and 0.044 (HepG-2) for the copper and cobalt complexes; respectively.

The present study pertains to the synthesis and characterizations of nine novel mixed-ligand complexes of [Zn(Hdmpz)2(L1)2] (1) (dmpz = 3,5-dimethylpyrazolate, L1 = 2-bromobenzoate), [Zn(Hdmpz)2(L2)2] (2) (L2 = 4-tert-butylbenzoate), Zn(Hdmpz)2(L3)2 (3) (L3 = 2-thiophenoate), [Zn(Hdmpz)2(L4)2] (4) (L4 = 4-methylsalicylate), [Cd(Hdmpz)2(L5)2]2 (5) (L5 = 2,6-dihydroxy benzoate), [Cd(Hdmpz)2(L6)2]2·2H2O (6) (L6 = 3-(4-methoxy-phenylcarbamoyl)-acrylate), [Zn(Hdmpz)2(L7)]2 (7) (L7 = acetylenedicarboxylate), [Zn(Hdmpz)2(L8)] (8) (L8 = 1,2-phenylenediacetate), and [Cd(Hdmpz)(L9)(H2O)2]·H2O (9) (L9 = 3-nitrophthalate). The resulting complexes were formulated via EA, IR, and SCXRD, and the TGA of all the complexes was also evaluated. The X-ray studies reveal that these complexes present mononuclear to dinuclear structures with tetrahedral geometry around each Zn2+, and octahedral/pentagonal bipyramidal geometry for Cd2+. The Hdmpzs in all compounds are coordinated only in monodentate fashion with its neutral N. The carboxylates at 1–4 and 3–9 function only as unidentate coordination units, the CO2− in 5 has the chelating bidentate coordination mode. Compound 6 contains both unidentate bridging and bidentate chelating COO−. The free carboxylate O at 2–4 and 7–8 accept the intramolecular N H⋯O H-bonds, at 1 and 7 the uncoordinated O participate in the intermolecular N H⋯O H-bonds. For 6 there is intermolecular N H⋯O H-bond from the NHCO and H2O, and intramolecular N H⋯O H-bonds from the NH at Hdmpz, the NHCO (acceptor), and one O at the bismonodentate coordinated COO−. One anion at 6 also gives the intramolecular N H⋯O H-bonds from the NHCO(donor) and one O at the bismonodentate coordinated COO−. The intermolecular N H⋯O H-bonds are from the phenol at both 4 and 5, and from the H2O at 9. The CH3 at Hdmpz in all compounds are participated in the noncovalent bonds except 3. The intricate intra- and intermolecular N H⋯O and O H⋯O H-bonds as well as C H⋯N, C π, O⋯O, Br⋯O, CH3⋯CH, CH2⋯C, CH3⋯C, C H⋯O, CH2⋯O, CH3⋯O, C H⋯S, C H⋯π, CH3⋯π, and π⋯π associations are elucidated by the X-ray crystallographic studies, which unite the discrete units into high-dimensional ordered supramolecular structures.

The reactions of complex [Fe2Ni(O)(Piv)6(Et2O)(H2O)2] (1) with 1,10-phenanthroline (phen) and 2,2′-bipyridine (bpy) gave the following new coordination compounds: the trinuclear complex [Fe2Ni(O)(Piv)6(phen)H2O]·(C2H5)2O (2), the tetranuclear ones [Fe2Ni2(OH)2(Piv)8(phen)2] (3) and [Fe2Ni2(OH)2(Piv)8(bpy)2] (4), depending on the crystallization conditions. According to single crystal X-ray diffraction data, all the compounds have molecular structures. The Mossbauer spectra of 1–3 correspond to high-spin Fe3+ ions in an octahedral environment consisting of oxygen atoms. The DC magnetic susceptibility studies and quantum-chemical analysis of intra- and intermolecular J pathways using broken-symmetry density functional theory (DFT) showed that all exchange interactions in tri- (1, 2) and tetranuclear (3) complexes are antiferromagnetic. The exchange coupling is weaker in 3 due to the lower ability of the bridging OH-groups to mediate superexchange. Thermal destruction processes have been studied for 2 and 3. The final products of thermolysis are the mixed oxide NiFe2O4.

A pyridyl–amine Schiff-base compound (L = N-(2-pyridylmethylene)benzene-1,4-diamine) reacted with several metal salts (Cd(NO3)2·4(H2O), Ni(NO3)2·6(H2O), Co(NO3)2·6(H2O), CoCl2·6(H2O), Co(ClO4)2·6(H2O)) to give molecular complexes: [M(L)2(NO3)]·(NO3) (M = Cd (1), Ni (2), Co (3)), cis-[Co(L)2Cl2] (C6H6) (4), and [Co(L)3]·(ClO4)2·(CH3CN)2·(H2O) (5). Complexes 1–3, whose starting compounds possess NO3− anions, were isostructural octahedral complexes. In complexes 3–5, whose starting compounds have the same metal but different anions, the anions in the products exhibited different coordination modes depending on the identity of the metal. In all complexes, the amine end of the ligand (L) remains uncoordinated. The thermal behavior of the complexes is also described.

Two Cu(II) complexes, namely, [CuL12(OAc)2]·MeOH 1 and [CuL22(OAc)2] 2 (OAc = CH3COO, acetate), were synthesized based on two 1,2,4-triazole fungicides of paclobutrazol (L1) and diniconazole (L2). The crystal structural analysis shows that the two obtained complexes have similar structures and both of them adopt octahedral coordination mode. The Cu(II) atoms in both the complexes lie on a crystallographic inversion center and are coordinated with two triazole groups and two acetate anions. To screen effective fungicides, the two complexes were investigated for antifungal activities against four selected fungi using mycelial growth rate method. The results demonstrate that the toxicity of complex 2 was 6.96–23.39 times greater than that of complex 1, since complex 2 possesses both C C linkage and 2,4-dichlorobenzene moiety, and shows higher synergy levels for the molecular-level mixture of copper cation and L2. The results also show that both the synthesized complexes showed superior activities of 1.20–5.94 times to those of their ligands. The DFT calculation results of the title complexes and their ligands reveal that the complexes have a new active site of metal cation, smaller HOMO–LUMO energy gaps and lower polarity than their ligands, which should be responsible for the enhanced bioactivities after complexation.

Novel bis-o-semiquinonato nickel complexes (2,2′-bpy)Ni(3,6-DBSQ)2 (1) and (1,10-phen)Ni(3,6-DBSQ)2 (2) was synthesized (2,2′-bpy - 2,2′-dipyridine; 1,10-phen - 1,10-phenanthroline; 3,6-DBSQ-anion-radical of 3,6-tert-butyl-o-benzoquinone). Single crystal X-ray diffraction study indicated distorted octahedral environment of nickel atom in both complexes. Variable temperature magnetic susceptibility measurement detected predomination of ferromagnetic exchange interactions between high spin nickel ion and anion-radicals of o-semiquinones. DFT calculations are in a good agreement with experimental structural and magnetic results.

Reversible crystal-to-crystal phase transition was observed for a zinc(II) complex [Zn(dmso)6][BPh4]2 [hexakis(dimethylsulfoxide-κO)zinc(II) bis(tetraphenylborate)] (dmso: dimethylsulfoxide) at 230 K. The reversibility was ascertained by a single-crystal X-ray method, and the phase transition temperature was determined by the differential scanning calorimetry (DSC). In the crystal at 293 K, the complex cation was centrosymmetric, and the six dmso moieties were disordered, while in the crystal at 90 K, reported previously, the symmetry around the zinc(II) ion was lower, and only one dmso moiety was disordered. It was concluded that the sulfur inversion motion of the dmso moieties was taking place in the high-temperature phase and that the motion stopped in the low-temperature phase. From the conformational analysis, the driving force of the phase-transition was attributed to the crystal packing effect of the bulky tetraphenylborate anions, which imposed the volumetric compression of the flexible complex cations.

A tridentate NNO donor Schiff base, 2,4-dichlorido-6-((3-(dimethylamino)propylimino)methyl)phenol (HL) and its three complexes [CdL2]·H2O (1), [NiL2] (2) and [NiLL′(DMF)] (3) (HL′ = 3.5-dichlorosalicylaldehyde) were synthesized and physicochemically characterized by means of elemental analysis, molar conductivity measurements, FT-IR, UV–Vis and NMR spectral studies. The molecular structures of all three complexes were confirmed by X-ray crystallography. In all three complexes, the metal ions are in distorted octahedral environments. [CdL2]·H2O (1) crystallized in a triclinic space group, whereas both [NiL2] (2) and [NiLL′(DMF)] (3) crystallized in the monoclinic crystal system. The crystal structures of the complexes exhibit different types of intermolecular interactions, which have been supported by Hirshfeld surface analysis and associated fingerprint plots. The luminescent properties of the Schiff base and the three complexes were studied, and the nature of the emission was found to be quenching.

A series of tetranuclear [Ni(II)2Ln(III)2] complexes of general formula [Ni2Ln2(L)(H2O)9(OH)4Cl]∙3H2O∙Cl (1, 2, 5) (Ln = Dy (1), Tb (2), Ho (5)) and [Ni2Ln2(L)(H2O)12Cl] ∙3H2O∙5Cl (3, 4, 6, 7) (Ln = Gd (3), Sm (4), Nd (6), Pr (7)); H4L = N,N’,N’’,N’’’-tetra(3-methoxysalicylidene)-pentaerythritol) have been synthesized. The molecular structures and magnetic properties of 1–7 are reported. Structural analysis indicated that this family of clusters consists of a tetranuclear [Ni(II)2Ln(III)2] core, supported by a tetrapodal Schiff base ligand. Both Ni(II) ions adopt a distorted octahedral coordination environment, whilst the two terminal Ln(III) ions exhibit distorted tricapped trigonal prismatic geometries and are coordinated by eight or nine oxygen donor atoms. Magnetic measurements revealed that the Dy derivative of complex 1 displays typical d single-molecule magnet behaviour with the presence of slow magnetic relaxation. By contrast, complexes 2–7, no obvious SMM behaviour was exhibited, however for the Gd derivative 3, a significant magnetocaloric effect was observed.

Ditopic ligand − 4,7-di(tert-butyl)-5,6-dihydro-1,3-benzodithiole-2,5,6-trione (o-quinone having fused 1,3-dithiolene-2-one cycle (-S-(C O)-S-) in back position) interacts with Mn2(CO)10 in toluene forming 2D-coordination polymer which layers are subdivided by the solvent molecules. Each manganese atom has six coordination environment which consists of square planar bis-dioxolene fragment and additional axial coordination is provided by two oxygen atoms of C O group of -S-(C O)-S- five-membered cycle from adjacent bis-dioxolene manganese fragment. Four bis-dioxolene manganese fragments form cycle which is the unit cell of 2D-polymer. Weak coordination of C O group with manganese atom can be simply destroyed. Re-crystallization of complex from tetrahydrofuran leads to the decomposition of the 2D structure and results in octahedral mononuclear (THF)2Mn(semiquinone)(catecholate) complex.

Three pyridine-based macrocyclic ligands, two containing one pyridine pendant arm (L1 and L2) and one containing piperazine rings in the macrocyclic scaffold (L3), with an increasing size of the macrocycle from 12-, 14- to 30-membered ring for L1–L3 were synthesized and characterized. A series of Ni(II) complexes with all these ligands, with molecular formulas [NiL1(CH3OH)](ClO4)2 (1), [NiL2(CH3CN)](ClO4)2 (2), and [Ni2L3(DMF)2(CH3CN)2](ClO4)4 (3) (DMF = N,N–dimethylformamide), was prepared and thoroughly characterized. Single crystal X-ray structural analysis confirmed that all the complexes have a coordination number of six and their geometries are close to octahedral. In the case of the mononuclear complexes 1 and 2, all the nitrogen atoms of the macrocycle are coordinated, however, in the dinuclear complex 3 with the piperazine-based ligand L3, two nitrogen donor atoms (of the total number of ten) are uncoordinated. The first coordination spheres of all the complexes are completed by solvent molecules. The values of effective magnetic moments, determined by the Evans method in solution, are 3.12, 3.19 and 4.36 µB for complexes 1, 2 and 3, respectively, which correspond well to the theoretical spin-only values.

Two energetic complexes, Fe2II(DTMone)2(H2O)6 (1) and Fe2IIIO(DTMone)2(H2O)12 (2) [H2DTMone = di(1H-tetrazol-5-yl) methanone] were synthesized and characterized by FT-IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The coordination complex (1) and (2) belong to the P21/n and P1 space group, respectively. Both Iron cations are six-coordinated in octahedral fashion, by N atoms and O atoms. However, the O atoms of (2) have one free atom which is different from (1). The structure of complex (2) is analogous to two dimension structure due to the oxygen ligands participating in the coordination. Their thermal stabilities were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Additionally, the DSC measurements display that the dehydrated polymers possess excellent thermal stability, and the thermal decomposition peak temperature is as high as 285 °C. The sensitivities to external stimuli were determined with BAM standard methods as for impact >40 J (TNT,15J) and for friction >360 N.

Three cobalt(II) isothiocyanato complexes with 4-methoxypyridine (4-MOP) as a co-ligand have been synthesized: catena-[Co(4-MOP)2(μ1,3-NCS)2] (1), trans-[Co(4-MOP)4(NCS)2] (2), and [Co(4-MOP)2(NCS)2] (3) and structurally characterized by IR, UV–Vis spectroscopy and single crystal X-ray diffraction. The complexes 2 and 3 are discrete monomeric species with octahedral and tetrahedral geometries, respectively whereas the catena-[Co(4-MOP)2(μ1,3-NCS)2] (1) is featuring a polymeric 1D system with doubly bridging NCS− groups through the terminals N- and S-donor atoms in a trans octahedral geometry. The thermoanalytical behavior of 1–3 is reported. Magnetic susceptibility of the bridged-isothiocyanato coordination polymer 1 was studied down to a temperature of 2 K and at various magnetic dc and ac fields. These measurements indicate a metamagnetic transition in 1.

Two Zn-based metal–organic frameworks (MOFs) of pyridinemethanol–carboxylate conjugated ligands, namely, [Zn(L1)]n xSol (1, 3D) and [Zn(L2)2]n (2, 1D) (H2L1 = 4-(6-(hydroxymethyl)pyridin-3-yl)benzoic acid; H2L2 = 3-(6-(hydroxymethyl)pyridin-3-yl)benzoic acid) have been synthesized and structurally characterized. The dimensionalities of 1 and 2 are defined by the deprotonation states of the ligands. Specifically, the 3D MOF 1 features a rod-shaped Zn–O/COO chain as the secondary building unit (SBU) which effectively hinder network interpenetration, whereas the 1D chain of 2 mimics an edge-sharing octahedron with each Zn center serving as the vertex. MOF 1 reversibly uptakes CO2 and exhibits a Brunauer–Emmett–Teller (BET) surface of 345 m2 g−1, and remains crystalline upon activation, an indication of permanent porosity.

One cadmium–DNDZ [DNDZ = 2-(dinitromethylene)-1,3-diazacyclopentane] complex [Cd(NH3)4(DNDZ)2 (1)] and three unexpected cadmium–ADNA [ADNA = N-(2-aminoethyl)-2,2-dinitroacetamide] metal–organic frameworks (MOFs) {[Cd(NH3)2(ADNA)2]n (2), [Cd(CH3NH2)2(ADNA)2]n (3) and [Cd(CH3CH2NH2)2(ADNA)2]n (4)} were first synthesized by reactions of cadmium nitrate and DNDZ potassium salt in different aqueous amines. DNDZ molecules underwent a ring-opening reaction resulting in the formation of a new chain-like molecule ADNA, which is found for the first time and only in the cadmium(II) coordination environment compared with the previous other metal–DNDZ complexes, so the cadmium(II) ions should have special catalysis to the ring-opening reaction. The single crystal structures of complexes 1, 3 and 4 were obtained. The central cadmium(II) ion can form a distorted octahedral structure with six coordination atoms. Thermal behaviors and impact sensitivities of the four complexes were studied. Complex 1 presents one exothermic decomposition process (248.17 °C) after two consecutive endothermic processes, but the three MOFs present only one exothermic decomposition process and their peak temperatures are close to one another (about 168 °C). The impact sensitivities of the four complexes are tested to be >20 J for 1, >16 J for 2, >17 J for 3 and >11 J for 4, respectively.

Four new complexes of copper(II) consisting of two different chromone derivatives with carbonyl and amine donor atoms: 7-aminoflavone (L1) and 7-amino-2-methylchromone (L2), were synthesized and characterized by X-ray diffraction, UV–Vis, FT-IR, EPR spectroscopy, MS and elemental analysis. The complexes were synthesized using 2:1 ligand-to-metal ratio, but while three products [Cu(L2)2Cl2]2 (1b), Cu(L1)2(ClO4)2(H2O)2 (2a), Cu(L2)2(ClO4)2(H2O)2 (2b) maintained the applied stoichiometry, the fourth compound showed an unexpected 1:1 ratio and was identified as [Cu(L1)Cl2]n (1a). In all four compounds, the chromone derivatives were found to act as monodentate O- or N-ligands. Interestingly, in a doubly chloro-bridged dinuclear complex 1b each Cu(II) cation interacts with one L2 ligand through the carbonyl O-donor, and with another L2 molecule through the amine N-donor, so the complex adopts a square pyramid geometry. According to a single-crystal X-ray diffraction analysis the complex 2b is a distorted mononuclear octahedron with the central Cu(II) cation interacting only with oxygen donors (two perchlorate anions, two L2 ligands, and two water molecules). The structural characteristics of 1a and 2a complexes were elucidated from EPR measurements, where their g-tensor components were compared to those observed for 1b and 2b, the structures of which were determined by X-ray diffraction method. DFT calculations were performed to estimate the most favored mode of coordination, whereas comparative Hirshfeld surface studies were used to characterize intermolecular interactions in the studied complexes. Magnetic interactions of 1a and 2a were also analyzed.

Zinc stannate (Zn2SnO4) that used for detecting traces of H2S was less concerned. In this work, Zn2SnO4 octahedra with the average size of 0.18 μm were prepared through a facile hydrothermal method followed by an annealing process in air atmosphere. The fabricated sensor shows excellent selectivity and sensitivity to H2S at working temperature of 170 °C. The gas response exhibits good linear relationship with the increasing of concentrations in the range of 5 –10 ppm. The response to 100 ppm H2S can reach up to 172.5 and the lowest detection limit is down to 5 ppb. Such outstanding gas property might be attributed to the morphology of the octahedra and the increased contact area between Zn2SnO4 and target gas, which may has potential applications in detecting traces of H2S.

Four new transition metal fluorosulfates NH4MSO4F (M = Mn, 1; Fe, 2; Co, 3; Ni, 4) were solvothermally synthesized in the solvent of N,N-dimethylacetamide (DMA) with HF as the mineralization agent. The X-ray single crystal diffraction analyses revealed that 1–4 are isomorphous, and possess a three-dimensional framework with the same structural topology as the known nonlinear optical material KTiOPO4 (KTP). The four compounds were constructed from MO4F2 octahedra and SO4 tetrahedra to form two kinds of intersecting 6-membered ring channels along the a and c axes, respectively. Within the channels locate the NH 4 + cations from the decomposition of DMA molecules. All the compounds are thermally stable up to 330 °C. The magnetic studies of 1–4 revealed the antiferromagnetic interaction behaviors in the range of 1.8–300 K.

The synthesis of the novel redox active ligand 3-(2′,6′-pyrimidine)-benzo-1,2,4-thiadiazine (pmbtdaH) is reported. The radical pmbtda can be prepared by in situ 1e− oxidation and its radical character confirmed by EPR spectroscopy, along with DFT calculations of the spin density distribution. Reaction of pmbtdaH with ZnCl2·2H2O in a 1:1 mol ratio afforded the dinuclear complex Zn2Cl4(pmbtdaH)2 (1) in which the two trigonal bipyramidal metal centres are linked via μ2-bridging Cl− ligands while the pmbtdaH ligand binds in an N,N′-chelate fashion via N(4) and the pyrimidinyl N(1) atom. The outcome of the reaction of pmbtdaH with Zn(hfac)2 (hfac = hexafluoroacetylacetonate) proved sensitive to the crystallization method; the mononuclear octahedral complex Zn(hfac)2(pmbtdaH) (2) in which the ligand coordinates in a similar N,N′-chelate fashion to that observed in 1 was isolated by layering a concentrated CH2Cl2 solution with hexane. Conversely the same reaction mixture afforded the tetranuclear complex Zn4(hfac)6(pmbtdaox)2 (3) when left undisturbed in a sealed vial. In 3 the ligand is both deprotonated and oxidized forming an anionic ligand in which there are two potential N,N′-chelate pockets and an additional S-oxide donor. The pmbtdaox− ligand bridges between a Zn(hfac)2 and a Zn(hfac) unit to form Zn2(hfac)3(pmbtdaox). Two such Zn2(hfac)3(pmbtdaox) units dimerise through the S-oxide oxygen atom to form a centrosymmetric tetranuclear Zn4(hfac)6(pmbtdaox)2 cluster. The structures of 1–3 have been determined by X-ray diffraction, elemental analysis, IR and UV–Vis spectroscopies as well as 1H NMR spectroscopy for complex 2.

Cadmium(II) complexes of thioureas, [Cd(Tu)(SO4)(H2O)2]n (1), [Cd(Dmtu)(SO4)(H2O)2]n (2) and [Cd(Mpy)2(SO4)]n (3) (Tu = thiourea, Dmtu = N,N′-dimethylthiourea and Mpy = 2-mercaptopyridine) were prepared and characterized by IR and NMR spectroscopy, and thermal analysis. While the solid state structure of 1 is known in the literature, the structures of 2 and 3 were determined by single crystal X-ray crystallography. Complexes 2 and 3 exist in the form of one-dimensional polymers. In 2, each cadmium atom is octahedrally coordinated by two doubly bridging Dmtu ligands, two sulfate ions and two water molecules. In 3, the octahedral coordination at the cadmium atom is attained by four bridging Mpy ligands and two sulfate ions. The results of the thermal analyses of 1 and 2 indicate a good correlation between the calculated and found weight loss values. The IR spectra of 1–3 were simulated and interpreted by means of periodic DFT calculations of their modelled polymeric solid state structures. The IR and NMR spectroscopic data are consistent with sulfur coordination of the thiones and oxygen coordination of the bridging sulfato group to the cadmium(II) ions. The antimicrobial activities of the complexes were evaluated by their minimum inhibitory concentrations and the results showed that the complexes exhibit moderate activities against gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The activities against molds (Aspergillus niger and Penicillium citrinum) were poor, while the complexes were almost ineffective against yeasts (Candida albicans and Saccharomyces cerevisiae).

Five two-dimensional metal–organic coordination compounds (MOCCs) have been solvothermally synthesized by the combination of 2-aminonicotinic acid (ANA) and transition metal ions, viz. Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), in water–ethanol mixed solvent. They are formulated as [Co(C6H5N2O2)2], (Co–ANA); [Ni(C6H5N2O2)2], (Ni–ANA) [Cu(C6H5N2O2)2], (Cu–ANA), [Zn(C6H5N2O2)2], (Zn–ANA) and [Cd(C6H5N2O2)2], (Cd–ANA). Single crystal X-ray diffraction studies for the complexes Co–ANA, Ni–ANA and Cd–ANA have also been carried out. These three complexes crystallize in the tetragonal crystal system with the space group P41212. The metal ions in all these complexes have an octahedral coordination environment. The six coordinations are satisfied by two pyridine N-atoms from two different ANA ligands and four oxygen atoms from two chelating carboxylate groups of another two ANA ligands. The topological motif of the coordination network is defined as 2-periodic net or square lattice (sql). These complexes were further characterized by elemental, FT-IR spectral, thermal and powder X-ray diffraction analyses.

Three one-dimensional coordination polymers, namely {[Mn(L)(Cl)2(H2O)]·(CH3)2CO)}n (1), {[Co(L)(Cl)2]}n (2) and {[Zn(L)(Cl)2]}n (3), were obtained from the self-assembly reactions of the dispiro-dipyridyloxy-cyclotriphosphazene ligand (L). All the isolated crystalline compounds were structurally characterized by elemental analysis, IR spectra, thermal analyses (TGA) and single crystal X-ray diffraction. X-ray crystallography revealed that all the complexes crystallized in the monoclinic crystal system with the P 21/c space group and the ligand (L) exhibited the same κ2N coordination binding mode with the divalent metal ions (Mn(II), Co(II) and Zn(II)) to form one-dimensional chain structures. The central Mn(II) ion has a distorted octahedral coordination geometry, whereas the Co(II) and Zn(II) ions have a distorted tetrahedral coordination geometry in the complexes. Complexes 2 and 3 are isostructural. The IR spectra illustrated that the P N stretching frequencies of the complexes show some changes when compared to the free ligand L. The UV–Vis properties and thermal stabilities of L, 1, 2 and 3 were also investigated. The ground state absorption spectra of maximum absorbance wavelength were recorded at 260 nm in acetonitrile solution for all the compounds. It was observed that the complexes give a stronger absorption band than the free ligand. According to TGA analysis, the coordination polymers exhibited thermal stability up to 300 °C.

Two new trinuclear copper(II) complexes, [(CuL1)3(μ3-OH)](ClO4)2 (1) and [(CuL2)3(μ3-OH)](ClO4)2·5H2O (2), and one new dinuclear Cu(II) complex, [(CuL3)2(μ2-OH)(CH3OH)]ClO4 (3), have been synthesized using three tridentate NNO donor Schiff bases, HL1, HL2 and HL3 (HL1 = 1-((2-aminoethylimino)methyl)naphthalen-2-ol, HL2 = 1-((2-(methylamino)ethylimino)methyl)naphthalen-2-ol and HL3 = 1-((2-(dimethylamino)ethylimino)methyl)naphthalen-2-ol), respectively and structurally characterized by single-crystal X-ray diffraction. Complexes 1 and 2 consist of trinuclear [(CuL)3(μ3-OH)]2+ units, whereas 3 contains dinuclear [(CuL)2(μ2-OH)]+ unit along, with perchlorate anions which are needed to balance the charge. In each of the complexes, all the copper atoms are five-coordinated with a distorted square-pyramidal geometry, except for complex 1 in which one of the Cu(II) ions of the trinuclear unit is six-coordinate, being weakly coordinated to one of the perchlorate anions to form an elongated distorted octahedron. The equatorial plane consists of the bridging oxygen of the central OH− group together with three atoms (NNO) from the Schiff base. The phenoxido oxygen atom of the Schiff base coordinates to the axial position of the Cu(II) ion of another subunit to form the cyclic trimer in 1 and 2 and dimer in 3. Magnetic measurements of complexes 1–3 in the 2–300 K temperature range indicate antiferromagnetic coupling in the complexes with J = −8.85, −4.86 and −50.60 cm−1 for 1–3 respectively. Density Functional Theory has also been performed in order to estimate the exchange coupling constants in these three complexes. The theoretically calculated J values are in good agreement with the experimental values.

Four new energetic nickel complexes of DNDZ [DNDZ = 2-(dinitromethylene)-1,3-diazacyclopentane], Ni(NH3)2(DNDZ)2 (1), Ni(CH3NH2)2(DNDZ)2 (2), Ni(C2H5NH2)2(DNDZ)2 (3) and Ni(C3H7NH2)2(DNDZ)2 (4), have been first synthesized and characterized. The crystal structures studies of 1 and 2 show that the central nickel(II) ion is six-coordinated by two O atoms and two N atoms from two DNDZ− anions and two N atoms from ammonias (methylamines) to form a distorted octahedral structure. Thermal decomposition processes of the four complexes were studied. The kinetic parameters of the exothermic decomposition process, specific heat capacities and adiabatic times-to-explosion for the four complexes were analyzed. All calculation and research results indicate that these complexes present relatively low thermal stability and easily decompose. Sensitivity tests reveal that the complexes are less sensitive to mechanical stimuli.

We report on the novel series of (CH3)3SPbI3−xBrx and (CH3)3SPbI3−xClx (x = 0, 1, 2, 3) perovskite compounds. X-ray diffraction analysis shows that the solid solutions of (CH3)3SPbI3−xBrx (x = 0, 1, 2, 3) and (CH3)3SPbI3−xClx (x = 0, 1, 2) crystallize in hexagonal symmetry (space group P63mc, No. 186) with 1D columns of face-sharing [PbX6] octahedra. (CH3)3SPbCl3 crystallizes in orthorhombic symmetry (space group Pnma, No. 62) forming 3D network of vertex- and face-sharing [PbCl6] octahedra. Optical and vibrational properties were investigated using UV–vis reflectance, photoluminescence and Raman spectroscopy at room temperature. The compounds show high chemical stability in ambient air at temperatures up to 80 °C and under solar simulator, in contrast to the hygroscopic CH3NH3PbI3 or CH(NH2)2PbI3 that are commonly used in perovskite solar cells. First principles theoretical ab initio and efficient semiempirical extended Huckel calculations were performed to evaluate the energy band gap values, whose results are in good agreement with the experimentally determined values.

The structures of the monohalomercury(II) complexes, [HgX]+, in dimethylsulfoxide (dmso), pyridine and N,N-dimethylthioformamide (dmtf) solution have been studied by means of EXAFS. All complexes in the Hg2+-X− systems, X = Cl, Br and I, in dmso and pyridine have the unique property with wide range of predominance of all individual complexes. This means that all complexes can be individually characterized in solution. The previously reported complex formation thermodynamics in dmso and pyridine predicted a substantial desolvation at the formation of the first complex. This study shows that the dmso and pyridine solvated [HgX]+ complexes have one solvent molecule strongly bound “trans” to the halide ion and another two weakly bound solvent molecules in the remaining positions of linearly distorted tetrahedra. This shows that a substantial desolvation of the hexasolvated mercury(II) ions takes place at the formation of the [HgX]+ complexes. The strongly bound dmso molecule binds through its oxygen atom to mercury(II) in the [HgCl]+ and [HgBr]+ complexes, while in the [HgI]+ complex through its sulfur atom. The Hg–X bonds are slightly shorter in the [HgX]+ complexes than in corresponding [HgX2] complexes, and the short Hg–O and Hg–N bond distances are ca. 0.35 and 0.25 A shorter than in the octahedral hexakis(dmso)- and -(pyridine)mercury(II) solvates, respectively. In dmtf solution, the dmtf solvated mercury(II) ion is four-coordinate in tetrahedral fashion. The structures of the dmtf solvated [HgX]+ complexes show the same basic tetrahedral configuration as the mercury(II) solvate. This shows that a simple substitution reaction takes place at the formation of the [HgX]+ complexes in dmtf.

Reaction of the Group 13 triflates, M(OTf)3 (M = Al, Ga, In; OTf = CF3SO3−), with 3 mol. eq. of R3PO (R = Ph or Me) gives the six-coordinate complexes, [M(OTf)3(R3PO)3], with coordinated triflate, as white powdered solids. Similarly, using 3 mol. eq. of PyNO (pyridine-N-oxide) readily forms [In(OTf)3(PyNO)3], whose crystal structure confirms a mer octahedral arrangement. In contrast, reaction of the harder Lewis acids Al(III) and Ga(III) with PyNO produce mixtures, mostly likely of the 3:1 and 4:1 species, [M(OTf)3(PyNO)3] and [M(OTf)2(PyNO)4][OTf] (M = Al, Ga). Both of the tetrakis species have been confirmed via single crystal X-ray studies and shown to exist as trans isomers. Higher ratios (4:1, 5:1 and 6:1) of Me3PO coordinated to In(OTf)3 can also be achieved by varying the reaction stoichiometry appropriately, with the coordinated OTf groups readily displaced by the Me3PO. Crystal structures of two polymorphs of the salt, [In(OTf)2(Me3PO)4][In{(OH2)2(OTf)4}(Me3PO)4], in which the [In{(OH2)2(OTf)4}(Me3PO)4]− anion is (unusually) comprised of a ‘InIII(OH2)2(Me3PO)4′ unit with four OTf anions H-bonded to the aquo ligands, giving the overall monoanionic charge. A similar arrangement is present in [In(OTf)2(Ph3PO)4][In{(OH2)4(OTf)4}(Ph3PO)2], the structure of which shows that all of the H atoms associated with the four aquo ligands in the [In{(OH2)4(OTf)4}(Ph3PO)2]− form significant H-bonds to the OTf groups; specifically, the four OTf− anions each show two O⋯H interactions, forming bridges that link the equatorial aquo ligands into a 24-membered ‘pseudo-macrocyclic’ ring. The crystal structure of the mononuclear 5:1 complex, [Ga(Me3PO)5(MeCN)][OTf]3, is also described. Using the diphosphine dioxide, dppmO2 (Ph2P(O)CH2P(O)Ph2), with M(OTf)3 in a 3:1 ratio readily affords the tris-chelate species, [M(dppmO2)3][OTf]3 for all three metals, while a 2:1 ratio also gives [Ga(OTf)2(dppmO2)2][OTf]. Crystal structures of both [Al(dppmO2)3][OTf]3·MeCN and [Ga(dppmO2)3][OTf]3·2CHCl3 are reported. Multinuclear (1H, 13C{1H}, 19F{1H}, 31P{1H}, 27Al, 71Ga and 115In, where appropriate) NMR data show that in CD3CN the complexes are labile and the different R3PO coordination environments are not distinguished (although exchange between coordinated and ‘free’ Me3PO is slow on the 31P NMR timescale), while the MeCN solvent also replaces OTf in the metal coordination sphere.

Four new examples of copper complexes [Cu(L1)2(H2O)4] (1), [Cu(HL1)2(H2O)2](NO3)2 (2), [Cu(HL1)Cl]∞ (3), [Cu(HL2)(phen)(H2O)](NO3)·3(H2O) (4) with HL1 = vitamin B3, H2L2 = 2-hydroxy-vitamin B3, phen = 1,10-phenanthroline, were synthesized and their structures solved by single crystal X-ray diffraction. For all complexes, vitamin B3 acts as monodentate ligand through the N atom from pyridyl group or the oxygen atom from the carboxylate group. The copper centers exhibit different geometries, namely octahedral (1), square planar (2), tetrahedral (3) and square pyramidal (4). Intermolecular π⋯π interactions as well as an H-bonding network were observed for all complexes. The antitumor capacity of the complexes was tested in vitro against a human cancer cell line, the colorectal adenocarcinoma (Caco-2) cell line, by determining their effect on cell viability, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide as reagent. Noteworthy, complex of copper(II) with hydroxyl-vitamin B3 and phenanthroline (4) showed a considerable lower IC50 value (30 (24–38) μM), when compared with vitamin B3, phenanthroline and cisplatin against the same cell line.

Five new metal(II) dicyanamide (dca) complexes with 4-hydroxymethylpyridine (4-OMP) and 4-methoxypyridine (4-MOP) have been synthesized, [Co(dca)2(4-OMP)2]n (1), [Cu(dca)2(4-OMP)2]n (2), [Cu(dca)2(4-MOP)2]n (3), [Cd(dca)2(4-MOP)2]n (4), [Zn(dca)2(4-MOP)2]n (5) and characterized by IR, UV–Vis spectroscopy and single crystal X-ray diffraction. The isostructural polymeric 1-D complexes feature double µ1,5-bridging dicyanamide ligands and terminal 4-OMP or 4-MOP ligands in trans-conformation around the distorted M(II) octahedra. The magnetic properties of complexes 1 and 2 are reported.

Three new trinuclear hetero-metallic complexes, [(NiLR)2Fe(N3)3] (1), [(NiLR(H2O))2Fe(C6H5CH2CO2)2]·(HSO4) (2) and [(NiLR(H2O))2Fe(C6H5CO2)2]·(HSO4)·(H2O)·(CH2Cl2) (3) have been synthesized using [NiLR] as a “metalloligand” (where H2LR = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine). All complexes have been characterized by elemental analysis, spectroscopic methods, single crystal XRD and magnetic study. In the angular trinuclear units of 1, the two terminals [NiLR] coordinate through double phenoxido bridges to the central FeIII ion which is penta-coordinated having terminally coordinated azide ion. The two terminal NiII centers are connected to each other and also to neighbouring units through μ1,3-azido bridges to form an alternating chain. On the other hand, complexes, 2 and 3 are linear discrete trinuclear species [NiII–FeIII–NiII] in which two terminal octahedral [NiLR] units coordinate to the central octahedral FeIII ion, located on a crystallographic centre of symmetry, through a μ2-phenoxido oxygen atom and a bridging carboxylato ion. Variable temperature magnetic susceptibility measurements show the presence of antiferromagnetic exchange interactions in 1 mediated through the phenoxido bridges (J1 = −33.2 cm−1,) and μ1,3-N3 single bridges (J2 = −19.9 cm−1 and J3 = −16.7 cm−1). On the other hand, compounds 2 and 3 show ferromagnetic coupling interactions mediated through the double phenoxido bridges with J values of +4.9 and +3.0 cm−1 for 2 and 3, respectively.

The synthesis and characterization of the hexanuclear [M 2 (κ O- O 2 CFc) 2 ( µ -O 2 CFc) 2 ( µ -H 2 O)(κ 2 N,N′ -tmeda) 2 ] (M II = Ni, 5 ; Co, 6 ; Fc = ferrocenyl, ( η 5 -C 5 H 4 )( η 5 -C 5 H 5 )Fe; tmeda = N,N,N′,N′ -tetramethylethylendiamine) and the trinuclear [Cu(κ 2 N,N′- tmeda)(κ 2 O,O′- O 2 CFc) 2 2 ] ( 7 ) coordination compounds are described. Compounds 5 – 7 were prepared by the consecutive reaction of ferrocene carboxylic acid (FcCO 2 H; 1 ) with [ n Bu 4 N]OH followed by treatment of in situ formed [ n Bu 4 N][FcCO 2 ] with the metal salts [M(tmeda)(NO 3 ) 2 ] (M = Ni, 2 ; Co, 3 ; Cu, 4 ). The structures of 5 – 7 in the solid state were determined by single crystal X-ray diffraction analysis. Isostructural 5 and 6 crystallise in the triclinic P 1 ¯ ( 5 ) and in the monoclinic space group P 2 1 /n ( 6 ). The two M II (tmeda) entities of 5 and 6 with M II = Ni, Co, respectively, are syn , syn -bridged by two FcCO 2 − functionalities and one µ -bridging water molecule. Additionally, two FcCO 2 − ligands are κ O -coordinated to each M II ion to form octahedral MN 2 O 4 coordination setups. A related MN 2 O 4 coordination setup is observed for 7 as well, whereby the Cu II ion is coordinated by two O 2 CFc and one tmeda ligand. Electrochemical investigations reveal that all individual Fc units of 5 – 7 are oxidized separately. Thermogravimetric analysis showed that 5 and 6 start to decompose at 110 and 125 °C and thus at significantly lower temperatures compared to 7 (200 °C). The mass residues obtained after decomposition are composed of Fe 2 O 3 , FeNi 3 and Fe 0.64 Ni = Ni 0.36 ( 5 ), Fe and Co 3 O 4 ( 6 ) and Cu 2 O and CuFeO 2 ( 7 ), as determined by powder X-ray diffraction analysis (PXRD). Thermal susceptibility measurements of 5 and 6 determined a weak antiferromagnetic coupling in 5 and 6 with J = 1.1 K and J = 1.9 K, respectively.

The reaction of [Re(CO)3(THF)Br]2 and 2,2′-bipyrimidine (bpm) in dichloromethane at room temperature employing a stoichiometric 2:1 ratio leads to a mixture of [(bpm)Re(CO)3Br] (21%) and anti-[Br(CO)3Re(μ-bpm)Re(CO)3Br] (79%). When a 1:1 ratio is used, only anti-[Br(CO)3Re(μ-bpm)Re(CO)3Br] is obtained in a 89% yield. The reaction of [Re(CO)5Br] and (bpm) leads to [(bpm)Re(CO)3Br] as a single product. [(bpm)Re(CO)3Br] and anti-[Br(CO)3Re(μ-bpm)Re(CO)3Br] display one and two rhenium(I) centers of distorted octahedral coordination geometry respectively, each with a facial ligand correlation. The intramolecular metal to metal distance is 5.8508(16) A in anti-[Br(CO)3Re(μ-bpm)Re(CO)3Br]. The HOMO-LUMO gap for [(bpm)Re(CO)3Br] results 0.74 eV larger (3.03 vs 2.29 eV) than the computed for anti-[Br(CO)3Re(μ-bpm)Re(CO)3Br]. In the same sense, the anti-isomer is computed to be 0.14 eV (13.4 kJ mol−1) more stable compared to the hypothetical syn-[Br(CO)3Re(μ-bpm)Re(CO)3Br]. Cyclic voltammetry shows that the difference between the ReI/Re0 reduction and its ReI/ReII oxidation in terms of potential is about 3.46 V for [(bpm)Re(CO)3Br], while this value diminishes to 2.62 V for anti-[Br(CO)3Re(μ-bpm)Re(CO)3Br]. Following this tendency, the MLCT band for [(bpm)Re(CO)3Br] is centered at 385 nm (DMF), while it is red-shifted almost 100 nm for anti-[Br(CO)3Re(μ-bpm)Re(CO)3Br]. While [(bpm)Re(CO)3Br] emits at 680 nm (excited at 380 nm), anti-[Br(CO)3Re(μ-bpm)Re(CO)3Br] remains non-emissive, which is attributed to a favored vibrational deactivation path.

Complex assembly preferences and resultant spin state choice and Jahn-Teller distortion mode in twelve Mn(III) complexes of varying nuclearity with Schiff base chelate ligands of different sizes are compared. Mononuclear complexes Mn(5-F-sal2323)]OTf (1), [Mn(5-F-sal2323)]ClO4 (2) and [Mn(5-F-sal2323)]NO3, (3) with the 8-carbon R-Sal2323 chelate type show rare axial compression at room temperature and complexes (2) and (3) also show reversible thermal spin state switching from spin quintet to triplet states on cooling. The prevalence of atypical axial compression is further probed by single crystal diffraction studies on high spin mononuclear complexes (4)-(7) with the longer 9-carbon R-Sal2333 chelate series using [Mn(3-OEt-sal2333)]BF4, (4) [Mn(3,5-diOMe-sal2333)]BF4·0.5PrOH, (5), [Mn(5-F-sal2333)]BPh4, (6) and Mn(5-NO2-sal2333)]BPh4, (7) as examples. Ring closure of both the 8-carbon R-Sal2323 and longer 9-carbon R-Sal2333 ligands was also observed yielding a ligand with a 6-membered ring in the mononuclear complex [Mn(3-OMe,5-NO2-sal23336R)·0.07MeOH·0.93MeCN (8) in contrast to a protonated 5-membered ring in the dimeric complex [Mn2(5-Cl-sal2323H5R)2](ClO4)2·1.85EtOH·0.33MeCN, (9) with the R-Sal2323 chelate type. Finally comparison of the assembly modes of Mn(III) complexes of the 8-carbon R-Sal2323 and 9-carbon R-Sal2333 series with those of the shorter 7-carbon R-Sal2322 ligand series reveal that the mononuclear assembly mode is not favoured with the smaller chelate. Instead three dimeric or cluster complexes with rearranged ligands were recovered in low yield. The structures of these complexes [Mn2(5-NO2-sal23225R)2]·2BuOH, (10), [Mn2(3,5-diBr-sal23225R)(3,5-diBr-sal)3]·0.7EtOH·2.61MeCN, (11) and [Mn2Na(3-NO2,5-OMe-sal23225R)]ClO4·0.5MeCN (12) are reported and compared with examples with the longer chain chelate ligands.

Di-, Tetra- and Hexanuclear Organostanoxanes were obtained from the organotin precursors such as (RSnCl3; R = 2-phenylazophenyl) and diorganotin precursor (R2SnCl2; R = 2-phenylazophenyl) having intramolecular N → Sn coordination. RSnCl3 on complete hydrolysis followed by reaction with benzoic acid in different stoichiometry in refluxing dry toluene afforded a hexanuclear [RSn(μ2-O)(μ2-O2CPh]6∙4PhCH3 (1) and a dinuclear [(RSn)2(μ2-O)(μ2-O2CPh)2(κ2-O2CPh)2]∙PhCH3 (2) monoorganostannoxane clusters. While diorganotin precursor (R2SnCl2; R = 2-phenylazophenyl) on complete hydrolysis in the presence of NaOH afforded a tetranuclear diorganostannoxane macrocycle [R2Sn(µ2-O)]4 (3). Single crystal x-ray diffraction analyses revealed that all the three complexes consist Sn centers in different coordination environment acquiring distorted octahedral, distorted pentagonal bipyramidal and distorted trigonal bipyramidal geometry respectively. Complexes 1–3 are further studied for their antibacterial activity which revealed complex 3 shows better antibacterial activity compared to the other complexes. From the DFT studies, we have found that the order of biological activity and HOMO-LUMO gap for these complexes are in similar order (3 > 1 > 2) which suggests that the biological activity and HOMO-LUMO gap are well correlated with each other for these complexes.

A number of binuclear and mononuclear macroacyclic Schiff base complexes containing piperazine moieties were synthesized. The binuclear complexes (M2L1) characterized by elemental analysis, IR and, also Ni(II) complex by a X-ray single crystal structural analysis. In this case, X-ray showed that each nickel atom is in a mer-N3O3 octahedral coordination environment. Moreover, mononuclear macroacyclic Schiff base complexes (ML2 and ML3) were prepared based on the condensation reaction of an amine containing piperazine moiety and 2-hydroxy banzaldehyde or formyl pyridine in 1:2 mol ratio in the presence of Ni(II), Cu(II), and Co(II) ions. All of compounds were characterized by elemental analyses, FT-IR, mass spectrometry and ligands characterized by 1H and 13C NMR spectroscopy. The cytotoxicity of the complexes was evaluated against two different cancer cell lines including MCF-7 (breast) and A549 (lung) adenocarcinoma cells. In general, binuclear complexes, possesses a higher cytotoxic effect against the tested cells than the other complexes. In addition, the biological assessment of complexes have been examined via molecular docking. As an interesting results, the binuclear complexes have the highest inhibition effect against cytotoxic receptors.