Search

Three novel heterometallic Ni/Cd coordination compounds [Ni(en)3][CdCl4]∙3dmso (1), [Ni(en)2(dmf)2][CdBr4] (2), and [Ni(en)3]2[CdI4](I)2 (3) have been synthesized through the self-assembly process in a one-pot reaction of cadmium oxide, nickel salt (or nickel powder), NH4X (X = Cl, Br, I), and ethylenediamine in non-aqueous solvents dmso (for 1) or dmf (for 2 and 3). Formation of the one- (1) or three-dimensional (2 and 3) hydrogen-bonded frameworks has been observed depending on the nature of the [CdX4]2− counter-anion, as well as on the nature of the solvent. The electronic structures of [Ni(en)3]2+ and [Ni(en)2(dmf)2]2+ cations were studied at the DFT and CASSCF levels, including the ab initio ligand field theory (AILFT) calculations. The non-covalent intermolecular contacts between the cationic nickel and anionic cadmium blocks in the solid state were investigated by the QTAIM analysis. The mechanism of ligand substitution at the nickel center in [Ni(en)2(dmf)2]2+ was theoretically investigated at the ωB97X-D4/ma-def2-TZVP//DLPNO-CCSD(T)/ma-def2-TZVPP level. The results demonstrate that thermodynamic factors are structure-determining ones due to low energy barriers of the rotation of dmf ligands in [Ni(en)2(dmf)2]2+ (below 3 kcal mol−1) and the reversible transformation of [Ni(en)2(dmf)2]2+ into [Ni(en)3]2+ (below 20 kcal mol−1). [ABSTRACT FROM AUTHOR]

The first three compounds based on a {copper–thiocyanate–dabco} combination, namely, (Hdabco)[Cu2(NCS)3] (1), (H2dabco)[Cu(NCS)3] (2), and [Cu(Hdabco)2(NCS)4]∙2dmso (3), where dabco = 1,4-diazabicyclo[2.2.2]octane were synthesized and characterized by single-crystal XRD, elemental analysis, Raman, and partial IR spectroscopy. In copper(I) derivatives, the influence of the charge of the organic cation on the dimensionality of the crystal structure is observed. Thus, in the case of 1, monoprotonated Hdabco+ cations provide the template for the formation of a polymeric anionic 3D framework {[Cu2(NCS)3]−}n, while in the case of 2, diprotonated H2dabco2+ cations together with discrete [Cu(SCN)3]2− anions generate a simple ionic 0D structure with an island-like crystal lattice. The anionic {[Cu2(SCN)3]−}n framework has infinite square channels of 10 × 10 Å size running along the 001 crystallographic direction. In 3, both the Hdabco+ and thiocyanato units behave as terminal monodentate ligands attached to copper(II) centers via N-donor atoms, forming neutral molecular complexes with an elongated (4+2) octahedral environment. The crystallization molecules of dmso are hydrogen bonded to the protonated parts of the coordinated dabco molecules. A series of by-products Cu(SCN)2(dmso)2 (4), (Hdabco)SCN (5), (H2dabco)(SCN)2 (6), and (H2dabco)(SCN)2∙H2O (7) were identified and characterized. [ABSTRACT FROM AUTHOR]

The four new complexes, [Cu(HL1)(L2)Cl] (1), [Cu(HL1)(L1)]∙Cl∙2H2O (2), [Co(L1)2]∙Cl (3) and [Cd(HL1)I2]∙dmso (4), have been prepared by one-pot reactions of the respective chloride or iodide metal salt with a non-aqueous solution of the polydentate Schiff base, HL1, resulted from in situ condensation of benzhydrazide and 2-pyridinecarboxaldehyde, while a ligand HL2, in case of 1, has been formed due to the oxidation of 2-pyridinecarboxaldehyde under reaction conditions. The crystallographic analysis revealed that the molecular building units in 1–4 are linked together into complex structures by hydrogen bonding, resulting in 1D, 2D and 3D supramolecular architectures for 1, 2 and 4, respectively, and the supramolecular trimer for 3. The electronic structures of 1–4 were investigated by the DFT theoretical calculations. The non-covalent interactions in the crystal structures of 1–4 were studied by means of the Hirshfeld surface analysis and the QTAIM theory with a special focus on the C–H⋯Cl bonding. From the DFT/DLPNO-CCSD(T) calculations, using a series of charged model {R3C–H}0⋯Cl− assemblies, we propose linear regressions for assessment of the interaction enthalpy (ΔH, kcal mol−1) and the binding energy (BE, kcal mol−1) between {R3C–H}0 and Cl− sites starting from the electron density at the bond critical point (ρ(rBCP), a.u.): ΔH = −678 × ρ(r) + 3 and BE = −726 × ρ(r) + 4. It was also has been found that compounds 1, 3 and 4 during in vitro screening showed an antibacterial activity toward the nine bacteria species, comprising both Gram-positive and Gram-negative, with MIC values ranging from 156.2 to 625 mg/L. The best results have been obtained against Acinetobacter baumannii MβL. [ABSTRACT FROM AUTHOR]

A unique π-conjugated benzothiadiazole-ortho-vanillin ligand (HL), characterized by single crystal X-ray diffraction and DFT calculations, has been prepared by condensation between 4-amino-benzothiadiazole (BTD) and ortho-vanillin. Its reaction with cobalt(II) acetate afforded the complex of formula [CoL2]·CH2Cl2 (1), for which the coordination environment of the cobalt centre is a distorted octahedron and the ligand acts as a monoanionic tridentate NNO chelate in its phenolate form. Intermolecular π–π stacking interactions between the π-conjugated BTD units provide an antiferromagnetic coupling pathway, as indicated by the analysis of the dc magnetic measurements of a crystalline sample of the complex and supported by DFT type calculations. The static magnetic behaviour of 1 is analysed according to spin–orbit coupling and zero-field splitting models. Remarkably, the complex exhibits slow relaxation of the magnetization under dc applied magnetic fields being thus a new example of field-induced mononuclear single-molecule magnet (SMM). [ABSTRACT FROM AUTHOR]

The mol­ecular bis-chelate complex (2-{[(2-hy­droxy­ethyl-κO)amino-κN]meth­yl}-6-meth­oxy­phenolato-κO)(2-{[(2-hy­droxy­eth­yl)imino-κN]meth­yl}-6-meth­oxy­phenolato-κO)copper(II), [Cu(C10H14NO3)(C10H12NO3)] or [Cu(HLim)(HLam); HLim = C10H14NO3; HLam = C10H12NO3, represents the first compound containing a salicyl­idene-2-ethano­lamine type ligand in both imino HLim (Schiff base) and amino HLam (reduced Schiff base) forms that has been structurally characterized on the basis of X-ray data. Two mol­ecules of the monodeprotonated ligands coordinate the CuII ion in an (N,Ophen)-bidentate and an (N,Ophen,Oalc)-tridentate fashion in the case of the imino and amino forms, respectively. The shape of the CuN2O3 coordination polyhedron is a distorted square-pyramid (geometry index τ5 = 0.26). Inter­molecular N—H···O and O—H···O hydrogen bonds, involving H atoms of the amino and hy­droxy­ethyl groups, create a two-dimensional supra­molecular array extending parallel to (010). [ABSTRACT FROM AUTHOR]

The title compound, [Fe(C3H7NO)6][Cd2Cl7], crystallizes in the trigonal space group R3̅ and is assembled from discrete [Fe(DMF)6] 3+ cations (DMF = N,Ndimethylformamide) and [Cd2Cl7] 3- anions. In the cation, the iron(III) atom, located on a special position of 3̅ site symmetry, is coordinated by six oxygen atoms from DMF ligands with all Fe—O distances being equal [2.0072 (16) A˚ ]. A slight distortion of the octahedral environment of the metal comes from the cis O—Fe—O angles deviating from the ideal value of 90 [86.85 (7) and 93.16 (7)] whilst all the trans angles are strictly 180. The central Cl atom of the [Cd2Cl7] 3- anion is also located on a special position of 3̅ site symmetry and bridges two corner sharing, tetrahedrally coordinated CdII atoms. The two Cd atoms and the central Cl atom are colinear. The two sets of terminal chloride ligands on either side of the dumbbell-like anion are rotated relative to each other by 30. In the crystal, the cations and anions, stacked one above the other along the c-axis direction, are held in place principally by electrostatic interactions. There are also C—H...Cl and C—H...O interactions, but these are rather weak. Of the six crystal structures reported to date for ionic salts of [Fe(DMF)6] n+ cations (n = 2, 3), five contain FeII ions. The title compound is the second example of a stable compound containing the [Fe(DMF)6] 3+ cation. The existence of both [Fe(DMF)6] 2+ and [Fe(DMF)6] 3+ cations shows that the DMF ligand coordination sphere can accommodate changes in the charge and spin states of the metal centre. [ABSTRACT FROM AUTHOR]

A new organic-inorganic hybrid salt [L]2[MnCl4] (I) where L+ is the 2-methyl-3-(pyridin-2-yl)imidazo[1,5-a]pyridinium cation, is built of discrete organic cations and tetrachloridomanganate(II) anions. The L+ cation was formed in situ in the oxidative cyclocondensation of 2-pyridinecarbaldehyde and CH3NH2·HCl in methanol. The structure was refined as a two-component twin using PLATON (Spek, 2020[Spek, A. L. (2020). Acta Cryst. E76, 1-11.]) to de-twin the data. The twin law (-1 0 0 0 - 1 0 0.5 0 1) was applied in the refinement where the twin component fraction refined to 0.155-(1). The compound crystallizes in the space group P21/c with two crystallographically non-equivalent cations in the asymmetric unit, which possess similar structural conformations. The fused pyridinium and imidazolium rings of the cations are virtually coplanar [dihedral angles are 0.89-(18) and 0.78-(17)°]; the pendant pyridyl rings are twisted by 36.83-(14) and 36.14-(13)° with respect to the planes of the remaining atoms of the cations. The tetrahedral MnCl42- anion is slightly distorted with the Mn-Cl distances falling in the range 2.3469-(10)-2.3941-(9)-Å. The distortion value of 0.044 relative to the ideal tetrahedron was obtained by continuous shape measurement (CShM) analysis. In the crystal, the cations and anions form separate stacks propagating along the a-axis direction. The organic cations display weak π-π stacking. The anions, which are stacked identically one above the other, demonstrate loose packing; the minimum Mn...Mn separation in the cation stack is approximately 7.49-Å. The investigation of the fluorescent properties of a powdered sample of (I) showed no emission. X-band EPR data for (I) at 293 and 77-K revealed broad fine structure signals, indicating moderate zero-field splitting. [ABSTRACT FROM AUTHOR]

The new heterometallic complex, aqua-1κO-bis(μ2-2-iminomethyl-6-methoxyphenolato-1κ2O1,O6:2κ2O1,N)bis(thiocyanato-1κN)calcium(II)copper(II), [CaCu(C8H8NO2)2(NCS)2(H2O)], has been synthesized using a one-pot reaction of copper powder, calcium oxide, o-vanillin and ammonium thiocyanate in methanol under ambient conditions. The Schiff base ligand (C8H9NO2) is generated in situ from the condensation of o-vanillin and ammonia, which is released from the initial NH4SCN. The title compound consists of a discrete binuclear molecule with a {Cu(μ-O)2Ca} core, in which the Cu···Ca distance is 3.4275-(6)-Å. The coordination geometries of the four-coordinate copper atom in the [CuN2O2] chromophore and the seven-coordinate calcium atom in the [CaO5N2] chromophore can be described as distorted square planar and pentagonal bipyramidal, respectively. In the crystal, O-H···S hydrogen bonds between the coordinating water molecules and thiocyanate groups form a supramolecular chain with a zigzag-shaped calcium skeleton. [ABSTRACT FROM AUTHOR]

The 3-Cl-6-amino-(2′-picolyl)-1,2,4,5-tetrazine ligand HL1 has been synthesized and structurally characterized. Its versatile coordination behavior has been evidenced through reactions with Cu(Hfac)2 and Cu(triflate)2 precursors, which provided mixed-valence bimetallic Cu1.5Cu1.5 complexes [Cu2(μ-Cl)(L1)2] 2 and [Cu2(μ-triflate)(L1)2] 5. Changing the Cu(ii) precursor and the solvent leads to the formation of mononuclear octahedral Cu(ii) complexes [CuCl2(HL1)2]·2CH3CN 3 and [Cu(Hfac)2(HL1)] 4, in which only the amino-pyridine unit is involved in the coordination of the metal center. In contrast, in complexes 2 and 5, the ligands are deprotonated and bridge the metal centers as pyridine-amido-tetrazine fragments, while a bridging chloride or triflate ligand completes the coordination sphere of the metal ions. The Cu–Cu distances of 2.4313(4) Å in 2 and 2.5198(10) Å in 5 lie among the shorter values within mixed-valence bimetallic Cu complexes. Mixed-valence character is strongly supported by DFT calculations, showing the equal repartition of the unpaired electron between the two metal centers. [ABSTRACT FROM AUTHOR]

The successful utilization of the “direct synthesis” approach yielded the unprecedented hexanuclear complex of formula [Co2MnII2MnIV2(L1)4Cl2(μ3-O)2(dmf)4]·2dmf (1) (H3L is the Schiff base derived from the condensation of salicylaldehyde and 3-aminopropane-1,2-diol). Single crystal X-ray analysis revealed that 1 crystallizes in the monoclinic system P21/c and it contains a rare mixed-valence {CoIII2MnII2MnIV2(μ2-O)8(μ3-O)2} core where all metal ions are linked through the phenolato and alkoxo groups of the L3− ligand. Besides the charge balance resulting from the X-ray structure, the oxidation state of the metal ions has been confirmed by XPS spectroscopy. Cryomagnetic studies indicate the coexistence of ferro- (MnIV–MnII, J2 = +1.10(3) cm−1, J3 = +2.19(3) cm−1; MnII–MnII, j = +0.283(3) cm−1) and antiferromagnetic interactions (MnIV–MnIV, J1 = −17.31(4) cm−1), with the six-coordinate CoIII ions being diamagnetic. DFT type calculations were carried out to substantiate these values. The energy diagram for the different spin states using the best-fit parameters shows the occurrence of six low-lying spin states (S = 0–5) which are close in energy but clearly separated from the remaining ones, with the ground spin state being S = 5. Complex 1 is found to be the first example where weak ferromagnetic exchange between MnII ions through the long –O–MnIV–O– pathway takes place. [ABSTRACT FROM AUTHOR]

The Schiff base H2L, namely 2‐(3‐methoxysalicylidene‐amino)‐benzyl‐alcohol, 1 and its two pseudo‐polymorphs H2L⋅CH3OH 2 and H2L⋅H2O 3, have been synthesized by the condensation reaction of 2‐aminobenzyl alcohol and o‐vanillin in different solvents. X‐ray crystallographic analysis revealed that the keto‐enol tautomerism of H2L in solid state exists as a complex system of three different enol, keto and zwitterionic forms in equilibrium, dependent on crystal packing forces and the crystallization solvent. The enol, keto and mixed enol‐zwitterionic (roughly 1:1) forms were observed in the crystal structures of 1, 2 and 3, respectively. The crystallographic results are supported by FTIR and DFT calculations. Photophysical properties were determined in acetonitrile solution and solid state and were supported by TD‐DFT studies. [ABSTRACT FROM AUTHOR]

A tetranuclear heterometallic complex formulated as [Co2Cu2(L)3(ea)(H2O)(NCS)2], where H2L = 2-((2-hydroxyethyl)iminomethyl)-phenol and Hea = 2-aminoethanol, has been obtained by self-assembly and characterized by single crystal X-ray diffraction. The crystal structure of the complex represents a new {CoIICoIIIM2} type of cobalt-based oxide cubane complex according to the classification which has been made via CSD structural analysis. [ABSTRACT FROM AUTHOR]

The “direct synthesis” approach, namely one-pot reaction of metal powders and ammonium salt with a methanol solution of a polydentate Schiff base (H2L) formed in situ from salicylaldehyde and ethanolamine, has been successfully used for the preparation of the new heterometallic compounds [Cu3Mn(L)4(CH3OH)3]I3 (1), [Cu3Mn(L)4(CH3OH)3(H2O)]NCS·H2O (2), [Cu3Mn(L)4(CH3OH)(H2O)2.55]Br·0.45H2O (3) and [Cu3Mn(L)4(H2O)3.4]BF4·0.6H2O (4). Crystallographic analysis revealed that 1–4 are based on the tetranuclear core {CuII3MnIII(μ3-O)4} where the metal centres are joined by the oxygen bridges of Schiff base ligands forming a cube-like arrangement. The novel heterometallic compound [Cu3Mn(L)4(CH3OH)3]2[Mn(NCS)4]·2CH3OH (5) has been obtained by the “building block” approach using the reaction of [Cu(HL)2] with manganese acetate and NH4NCS in methanol. The crystal structure of 5 revealed the {CuII3MnIII(μ-O)2(μ3-O)2} metal core which can be viewed as a double open cube. In spite of a similar {Cu3MnO4} atom set in the cores of 1–5, the complexes show rather different molecular structures and significantly differ by the number and combinations of coordinated CH3OH/H2O solvent molecules. Variable-temperature (2–300 K) magnetic susceptibility along with variable-field magnetization measurements of 1–5 showed a decrease of the effective magnetic moment value at low temperature, indicative of the antiferromagnetic coupling of medium size (−55 to −22 cm−1). For these systems resembling a compressed prism the coupling constant in walls J4 correlates with the averaged bonding angles in walls α: J4vs. α develops approximately according to a straight line. [ABSTRACT FROM AUTHOR]

Abstract: A new complex [Ni(L)Fe(CN)5NO]·2H2O (L=4,6,6-trimethyl-1,9-diamino-3,7-di-aza-nona-3-ene) has been obtained and characterized by means of X-ray crystallographic analysis and magnetochemistry. The Fe(CN)5NO2− anion links to the Ni(L)2+ cation through two bridging cyanide groups in a bent fashion. The intrachain Ni⋯Ni and interchain Ni⋯Ni distances are equal to 9.81(8) and 7.75(1) Å, respectively. The magnetic behaviour of the complex indicates the zero field splitting parameter D higher than 3cm−1 and the average exchange parameter (intra- and interchain) corresponding to direct Ni–Ni magnetic interaction in the crystal lattice equals ∼−0.2cm−1. [Copyright &y& Elsevier]

Abstract: Copper powder reacts with zinc oxide, ammonium chloride, ethylenediamine and methyl ethyl ketone in methanol solution to afford a bimetallic complex with the open chain diaminodiaza ligand – 4,5-dimethyl-1,9-diamino-3,7-di-aza-nona-3-ene (L1) containing the –CH2–CH(CH3)–C(CH3)inking the amine residues. The origin of the bridge was shown to be a result of template condensation of methyl ethyl ketone and formaldehyde arisen in the process of oxidation of methanol over copper powder acting in the reaction as both a source of metal and a catalyst. The crystal structure of Cu(L1)ZnCl4 was determined by X-ray diffraction and represents the first example of L1 to be crystallographically characterized. [Copyright &y& Elsevier]

Four new heterobimetallic complexes [CuL 1 ][MnCl 4 ] ( 1 ), [CuL 2 ][MnCl 4 ] ( 2 ), [NiL 1 ][MnCl 4 ] ( 3 ), [NiL 2 ][MnCl 4 ] ( 4 ) (L 1 = 4,6,6-trimethyl-1,9-diamino-3,7-di-aza-nona-3-ene; L 2 = 1,15-dihydroxy-7,9,9-trimethyl-3,6,10,13-tetra-aza-pentadeca-6-ene) have been prepared from elemental metals, ethylenediamine dihydrochloride or its N-(2-hydroxyethyl) derivative and acetone by the template condensation reaction. All complexes have been characterized by elemental analysis, IR and UV-Visible spectroscopy. The structures of 2 and 3 have been determined by X-ray crystallography ( 2 : Orthorhombic, Pna2 1, a = 20.136(4), b = 11.185(2), c = 10.251(2)Å, Z = 4; 3 : Orthorhombic, Pca2 1, a = 14.335(2), b = 11.405(2), c = 11.154(2)Å, Z = 4 ). Both crystals consist of alternating complex cations [ML] 2+ and anions [MnCl 4 ] 2- linked together by N-H···Cl-Mn and O-H···Cl-Mn hydrogen bonds forming 2D corrugated sheets in ( 2 ) and 1D helical chains in ( 3 ). Complex 2 represents the first single crystal structure elucidation of the complex containing L 2 . [ABSTRACT FROM AUTHOR]

The new heterometallic 2D polymer [Cu(en)2Cd(dca)2(SCN)2]n (en=ethylenediamine; dca=dicyanamide, N(CN)2−), the first example of a compound containing the unique mixed-anion Cd(dca)2(SCN)22− fragment, has been prepared from copper powder, cadmium dicyanamide, ammonium thiocyanate and ethylenediamine in methanol solution in air. The polymeric sheets of the compound comprise two different rings – 28-membered [Cu2Cd4(μ1,5-dca)2(μ1,3-NCS)4] macrocycles in which two 12-membered [Cd2(μ1,5-dca)2] rings form sections. [Copyright &y& Elsevier]

Copper powder reacts with cadmium oxide and ammonia acetate in methanol solution of ethylenediamine affording {[Cu(en)2][Cd2(O2CMe)6]}n in which seven-coordinated cadmium atoms are ligated by three bonding modes of acetate groups forming ladder-like anions [Cd2(O2CMe)6]2−n. The cations [Cu(en)2]2+ are located in the lattice and serve as bridges to connect separate anionic polymer chains into a two- dimensional network via hydrogen bonds. [Copyright &y& Elsevier]

A new organic-inorganic hybrid salt [L]2[MnCl4] (I) where L+ is the 2-methyl-3-(pyridin-2-yl)imidazo[1,5-a]pyridinium cation, is built of discrete organic cations and tetrachloridomanganate(II) anions. The L+ cation was formed in situ in the oxidative cyclocondensation of 2-pyridinecarbaldehyde and CH3NH2·HCl in methanol. The structure was refined as a two-component twin using PLATON (Spek, 2020[Spek, A. L. (2020). Acta Cryst. E76, 1-11.]) to de-twin the data. The twin law (-1 0 0 0 - 1 0 0.5 0 1) was applied in the refinement where the twin component fraction refined to 0.155-(1). The compound crystallizes in the space group P21/c with two crystallographically non-equivalent cations in the asymmetric unit, which possess similar structural conformations. The fused pyridinium and imidazolium rings of the cations are virtually coplanar [dihedral angles are 0.89-(18) and 0.78-(17)°]; the pendant pyridyl rings are twisted by 36.83-(14) and 36.14-(13)° with respect to the planes of the remaining atoms of the cations. The tetrahedral MnCl42- anion is slightly distorted with the Mn-Cl distances falling in the range 2.3469-(10)-2.3941-(9)-Å. The distortion value of 0.044 relative to the ideal tetrahedron was obtained by continuous shape measurement (CShM) analysis. In the crystal, the cations and anions form separate stacks propagating along the a-axis direction. The organic cations display weak π-π stacking. The anions, which are stacked identically one above the other, demonstrate loose packing; the minimum Mn...Mn separation in the cation stack is approximately 7.49-Å. The investigation of the fluorescent properties of a powdered sample of (I) showed no emission. X-band EPR data for (I) at 293 and 77-K revealed broad fine structure signals, indicating moderate zero-field splitting. [ABSTRACT FROM AUTHOR]