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In the reaction of (EtN)[WSCl] with 1,2-bis(diphenylphosphino)ethane in acetonitrile a new binuclear complex of tungsten(V) [WSCl(dppe)]·2CHCN is obtained. Its crystal structure is solved in the triclinic space group P-1 with the following unit cell parameters a = 10.1202(16) Å, b = 11.758(2) Å, c = 12.648(2) Å, α = 104.324(5)°, β = 106.469(5)°, γ = 97.587(5)°, V = 1364.9(4) Å, Z = 1, with the final refinement parameters R = 0.0545, wR = 0.1053. The work describes the synthesis, crystal structure, and Raman spectrum of the [WSCl(dppe)]·2CHCN complex. [ABSTRACT FROM AUTHOR]

Binuclear complexes of Pt(II) cycloplatinated with 2-phenylbenzothiazole and bridging ligands have been shown to contain the Pt-Pt bond. The complexes have been studied by X-ray diffraction, H NMR and electronic absorption spectroscopy, and electrochemical methods. The complexes cis-N,S-isomers with antisymmetric positions of the cyclometalated and the bridging ligands have been detected in the crystals as well as in the solutions. The low-wavelength absorption and luminescence of the complexes have been assigned to the metal-metal-ligand charge transfer. The two-electron oxidation and reduction waves in the voltamperograms are associated with the metal- and the ligand-centered processes, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] Preparation of Zn2+, Cd2+ and Hg2+ complexes of the new thiosemicarbazide. [•] Elemental analysis, spectral characterization of the ligand and complexes. [•] pH-metric studies in 50% dioxane–water mixture at different temperatures. [•] Thermal behavior of the solid metal complexes was studied using TGA technique. [•] The compounds were screened for antioxidant activity and cytotoxicity. [Copyright &y& Elsevier]

A new binuclear complex [Ag(ntb)](NO)·(CHOH)·(CHCN) based on a tripodal ligand ntb (ntb = tris(2-benzimidazolylmethyl)amine) has been synthesized and structurally characterized by X-ray single crystal diffractometry. In the structure of the complex each center Ag(I) ion is coordinated by two N atoms from two benzimidazole arm of one ntb ligand and one N atoms from one benzimidazole arm of the other in a trigonal coordinated geometry, resulting in the construction of a binuclear complex. The complex units are further linked into a 1-D chain by hydrogen bonds. The emission spectrum of the complex has been investigated and shows a red-shift of the emission peak compared to the ligand and the existence of ligand-to-metal charge transfer process (emission peak at 468.2 nm). Cyclic voltammogram of the complex indicates a pair of quasi-reversible redox couple, corresponding to the Ag/Ag electrochemical process. Graphical Abstract: In the structure of the complex each center Ag(I) ion is coordinated by two N atoms from two benzimidazole arm of one ntb ligand and one N atoms from one benzimidazole arm of the other in a trigonal coordinated geometry, resulting in the construction of a binuclear complex.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: 1,3-Diallylbenzimidazolin-2-one (2) reacts with silver tetrafluoroborate and hexafluorophosphate salts to furnish discrete binuclear complexes, whereas reaction with silver perchlorate and triflate salts provided 1D coordination polymers. Within each of the structures the ligand adopted a different coordination mode. [Copyright &y& Elsevier]

Tailoring the surficial chemical environment of two-dimensional materials by organic modification is an effective way to optimize their catalytic behaviors. Herein, we present a dynamic coordination approach to improve the photocatalytic performance of ultrathin Co 2 CO 3 (OH) 2 nanosheets (u-CoCH) in NIR light (λ > 780 nm) driven carbonylation reaction by using the reacting substrates (diamines) as the ligands. The coordination of diamines with surface Co2+ ions form a binuclear complex at the crystallographic planes of u-CoCH. The as-formed complexes can reduce the energy barrier of carbonylation reaction by weaking the N-H bond of the substrate on u-CoCH, and afford enhanced light response as well as the prolonged photogenerated electron lifetime. Together with the successful synthesis of a series of important structural motifs in pharmaceuticals and bioactive agents, the promoted photosynthesis reaction mode via in-situ formed surface complexes offers a model toward full-spectrum-solar-energy conversion in the field of chemical synthesis. [Display omitted] • Diamines act as substrate and ligand to tailor the surficial chemical environment of CoCO 3 (OH) 2 nanosheets. • The surface adjacent Co2+ ions binding to diamine molecules form a binuclear complex. • The complexes enhanced light absorption ability and reduced the energy barrier of carbonylation by weaking the N-H bonds. • A protocol for accessing cyclic ureas through NIR light driven carbonylation of diamine with CO over CoCO 3 (OH) 2. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two new 2,2′-bipyridine-based binuclear Cu (II) complexes have been synthesized. [•] The binary complex shows stronger binding affinity to DNA. [•] The two complexes bind to DNA via intercalation. [•] Their in vitro cytotoxicity reflects their DNA binding strength order. [•] Thermodynamic parameters indicate that the binding reactions are hydrophobic. [Copyright &y& Elsevier]

In the present work, a novel oxalate-bridged binuclear iron(III) complex of aminophenol derivative, (μ-ox-FeLNEM), where LNEM is deprotonated form of a tetradentate aminophenol ligand and ox stands for oxalate, was synthesized. The iron complex has been characterized by X-ray crystallography, infrared spectroscopy, UV–Vis, magnetic susceptibility studies and cyclic voltammetry techniques. X-ray structure analysis has revealed that each iron(III) is coordinated by two oxygen atoms of the oxalate group, two amine nitrogen’s and two oxygen atoms of phenolate ligand in an octahedral arrangement. The temperature variable magnetic susceptibility exhibits quite strong antiferromagnetic coupling between the two iron(III) centers. Cyclic voltammograms of the complex in dichloromethane at low temperatures showed two quasi-reversible cathodic peaks, corresponding to FeIII-FeIII to FeIII-FeII followed by FeIII-FeII to FeII-FeII process. [ABSTRACT FROM AUTHOR]

Abstract: Single crystals of a novel copper (II) complex with the amino acid l-arginine (l-arg) and cyclotetraphosphate, [Cu(l-arg)2(H2O)]2(P4O12)·8H2O, were prepared in aqueous solution and were characterized by X-ray diffraction, spectroscopy (diffuse reflectance, UV–vis and IR) and thermal analysis. Magnetic measurements and electronic structure calculations were also performed. Crystal structure determination reveals that this compound has a nonsymmetrical atomic arrangement, containing mainly a binuclear [Cu(l-arg)2(H2O)]2 4+ cation and an uncoordinated cyclotetraphosphate counter-anion (). The tetravalent cation contains two independent Cu(II) ions in two different chemical environments. This compound exhibits an antiferromagnetic (AFM) to paramagnetic (PM) phase transition at a temperature (T N) lower than 2K. The values of paramagnetic Curie–Weiss temperature (θ cw) and the exchange parameter (J/K B) emphasize the existence of an antiferromagnetic interaction between the neighboring copper ions. [Copyright &y& Elsevier]

We report here the synthesis and characterization of a few phenolate-based ligands bearing tert- amino substituent and their Zn(II) and Cu(II) metal complexes. Three mono/binuclear Zn(II) and Cu(II) complexes [Zn(L1)(HO)].CHOH.HO (1) ( H L1 = 6,6-(((2-dimethylamino)ethylazanediyl) bis(methylene)) bis(2, 4-dimethylphenol), [Zn(L2)] (2) ( H L2 = 2,2-(((2-dimethylamino)ethyl)azanediyl) bis(methylene) bis(4- methylphenol) and [Cu(L3).CH Cl] (3) ( H L3 = (6,6-(((2-(diethylamino)ethyl)azanediyl) bis(methylene)) bis(methylene)) bis(2,4-dimethylphenol) were synthesized by using three symmetrical tetradendate ligands containing NO donor sites. These complexes are characterized by a variety of techniques including; elemental analysis, mass spectrometry, H, C NMR spectroscopic and single crystal X-ray analysis. The new complexes have been tested for the phosphotriesterase (PTE) activity with the help of P NMR spectroscopy. The P NMR studies show that mononuclear complex [Zn(L1)(HO)].CHOH.HO (1) can hydrolyse the phosphotriester i.e., p-nitrophenyl diphenylphosphate (PNPDPP), more efficiently than the binuclear complexes [Zn(L2)] (2) and [Cu(L3).CHCl] (3). The mononuclear Zn(II) complex (1) having one coordinated water molecule exhibits significant PTE activity which may be due to the generation of a Zn(II)-bound hydroxide ion during the hydrolysis reactions in CHES buffer at pH 9.0. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A novel reaction pattern of heterodinuclear complexes was reported. Namely, nucleophilic attack of nBuLi/protonation of complexes [MnRe(CO)6(μ-S2CPR3)] occurs with the cleavage of the Mn–Re, (P)C–S bond and formation of new (Bu)C–S bond, to afford the novel complexes [MnRe(CO)6(μ-SnBu)(μ-S-C(H)PR3)] (L) (L=PR3, C5H5N) 3 and 4 which are different from previous complexes (1 and 2 or other complexes) obtained by the reduction with Na[Hg] or superhydride reagent. Additionally, in order to develop these complexes application, several similar structure Mn–Re binuclear complexes, MnRe(CO)6(μ-H)[μ-S(SnBu)CᆖC(PiPr3)S] (1), MnRe(CO)6(μ-H)[μ-S(SCH3)CᆖC(PiPr3)S] (2), MnRe(CO)6(μ-SnBu)[μ-SC(H)PCy3PPh3] (3), MnRe(CO)6(μ-SnBu)[μ-SC(H)PCy3Py] (4), which serve as structural models for the active site of Fe-hydrogenase, were chosen to investigate their possible electrochemical properties. Consequently, they are indeed shown to be electrocatalysts for H2 production in the presence of acetic acid in acetonitrile. The electrocatalysis is initiated by electrochemical reduction of these Mn–Re complexes, which subsequently, under weak acid conditions, undergo protonation of the reduced rhenium center to produce H2. And two probable electrochemical mechanisms (EECC and ECCE) are also proposed. [Copyright &y& Elsevier]

Abstract: The reaction of 2-pyridinecarboxaldehyde with K3Na[Mo(CN)4O2]·6H2O in water–ethanol solution at pH ca. 9 result in formation of an [{Mo(CN)3O}2(μ-pyr)]4− ion salt isolated as (PPh4)4[{Mo(CN)3O}2(μ-pyr-1κ2 N,O;2κ2 N,O)]·7H2O, where H2pyr=1,2-bis(2-pyridyl)ethene-1,2-diol. The X-ray crystal structure shows, that the pyr is in the form of endiol with Cd formal 2- charge. Cyclic voltammetry measurements indicate that binuclear complex can be reversibly oxidised to Mo(IV,V) with E 1/2 =+37mV and to Mo(V,V) at +262mV and reduced to Mo(III,III) at −468mV (scan speed 100mV/s). The formation of a Mo(IV,V) mixed valence complex is confirmed by the UV–Vis spectra in the presence of oxygen, [Copyright &y& Elsevier]

Abstract: Three (PR)2-bridged [2]ferrocenophanes (R =  t Bu (10a), n Bu (10b), and Ph (10c)) in which the two C5H4 rings of the ferrocene unit were bridged with a P(III)—P(III) bond were synthesized via Mg-mediated reductive coupling between the phosphorus centers of corresponding [Fe{C5H4P(Cl)R}2]. The P(Cl)R groups of [Fe{C5H4P(Cl)R}2] were derived from the P(NEt2)2 groups of [Fe{C5H4P(NEt2)2}2] as follows: the P(NEt2)2 group was first converted to P(Cl)NEt2 by HCl, and then R (R =  t Bu, n Bu, and Ph) was introduced to give P(R)NEt2, which was again allowed to react with HCl to form the P(Cl)R group. Of the three diphospha[2]ferrocenophanes, (P t Bu)2-bridged [2]ferrocenophane (10a) could be isolated as free diphosphine, while because of difficulty in their isolations as free ligands, the n Bu and Ph analogs (10b and 10c, respectively) were characterized as bis(pentacarbonylmetal) complexes (μ-10b)-[W(CO)5]2 (11) and (μ-10c)-[Cr(CO)5]2 (12), in which the respective phosphorus centers were coordinated to the pentacarbonylmetal fragments. X-ray analysis was performed for the three diphospha[2]ferrocenophanes, 10a, 11, and 12, demonstrating that their P—P bond lengths are 2.3093(7), 2.261(5), and 2.2502(8) Å, respectively. Because these tether P—P lengths are smaller than an ideal distance between the two parallel C5H5 rings of ferrocene, the two C5H4 rings of each of 10a, 11, and 12 are inclined from the parallel by 12.9°, 9.7°, and 13.6°, respectively. DFT calculations were performed on (PH)2-bridged [2]ferrocenophane as a model-compound, and showed that there are two conformational isomers. One, named the parallel form, features a P—P bond that is almost parallel to the axis passing through the centers of the two C5H4 rings, while the P—P bond of the other, named the twist form, leans with the two C5H4 rings twisted. The smaller inclined angle of 9.7° observed for 11 was found to result from its parallel-form conformation, while the C5H4 rings of 10a and 12 were more inclined due to adoption of the twist-form conformation. [Copyright &y& Elsevier]

Abstract: A new asymmetrical N,N′-bis(substituted)oxamide ligand, N-(5-chloro-2-hydroxyphenyl)-N′-[3-(dimethylamino)propyl]oxamide (C13H18N3O3Cl·H2O, H 3 L) and its two binuclear complexes [Cu2L(H2O)(bpy)](ClO4)·CH3OH (1) and [Ni2L(bpy)2](ClO4) (2) [bpy = 2,2′-bipyridine] have been synthesized and characterized by X-ray single-crystal diffraction. In the crystal structure, H 3 L adopting a transoid conformation occurs as a neutral molecule linked with a water molecule by an intermolecular hydrogen bond. In the two complexes, the cis-L3− ligand bridges two metal ions with the corresponding separations of 5.2032(15) Å (1) and 5.2466(7) Å (2), respectively. In vitro cytotoxic activities, and the reactivities of the three compounds towards DNA and protein are investigated. [Copyright &y& Elsevier]

Three new isostructural binuclear transition metal complexes with azido ion and 1,2-bis(3-(pyridin-2-yl)-1 H-pyrazol-1-yl)ethane (bppe), formulated as [M(N)(bppe)](ClO) (M = Co, 1; Ni, 2; Cu, 3), were successfully synthesized. They were structurally and magnetically characterized. In 1-3, the double azido ions link two adjacent octahedral metal centers together in the end-to-on mode (EO), with the M-N-M angles of 99.41°, 100.24° and 99.80°, respectively. The co-ligand bppe acts as terminal ligand to saturate the remaining coordination sites. The magnetic properties of 1-3 have been investigated in the temperature range of 2-300 K. Fitting of the magnetic susceptibility data revealed the occurrence of the strong ferromagnetic interactions [ J = 26.32 cm ( 1), J = 38.23 cm ( 2) and J = 139.83 cm ( 3)]. Density functional theory calculations have been performed on 1-3 to provide a magneto-structural correlation of the ferromagnetic behavior. [ABSTRACT FROM AUTHOR]

Abstract: Three pseudopolymorphs of a phenoxo-bridged binuclear manganese(III) complex, [Mn(L)(N3)]2 where L=[N,N′-bis(2-hydroxyacetophenylidene)]propane-1,2-diamine could be synthesized using same reactants but different solvents. The syntheses of the unsolvated isomer [Mn(L)(N3)]2 (1) and a hydrated isomer [Mn(L)(N3)]2·3.66H2O (2) have been achieved in acetone and methanol medium, respectively, while another previously reported complex [Mn(L)(N3)]2·2C2H5OH (3) was obtained from a mixed solvent containing ethanol. The pseudopolymorphs 1, 2 and 3 crystallize in the space groups P21/c, P21/n and P21/n, respectively. Their 3D supramolecular structures have been compared to notice that the molecular building blocks are held by weak intermolecular C–H⋯π, C–H⋯O or van der Waals interactions. While the compound 1 is an unsolvated pseudopolymorph, 2 and 3 contain water and ethanol, respectively as guest molecules in their lattices. [Copyright &y& Elsevier]

Abstract: Two novel binuclear heterobridged copper(II) Schiff base complexes of general formula [Cu2L(Pz)] (1) and [Cu2L(Az)(DMSO)]·DMSO (2) (where L=trianion of bis-azomethine derived from 1-phenyl-3-methyl-4-formylpyrazol-5-one and 1,3-diaminopropan-2-ol, Az=anion of 7-azaindole, Pz=pyrazolate anion) were synthesized and studied by IR spectroscopy and X-ray crystallography. Temperature dependence of magnetic susceptibility measurements show an antiferromagnetic coupling between two copper(II) ions in complex 1 (2 J=− 449) and ferromagnetic coupling in complex 2 (2 J =106cm−1). [Copyright &y& Elsevier]

Abstract: Reaction between hydrated lanthanide nitrates and tetramethyl propene-2,3-diphosphonate (MeO)2P(O)C(CH2)CH2P(O)(OMe)2, L, in trimethylorthoformate led to the isolation of two types of complex. Monomeric [Ln(NO3)3L2] are formed for the lighter lanthanides (La–Gd) whilst the smaller ions form dimeric complexes, [Ln2(NO3)6L3], where L bridges between the two lanthanides. The complexes have been characterised by infrared and 31P NMR spectroscopies and elemental analysis. The structures of [Pr(NO3)3L2] and [Yb2(NO3)6L3] are described. Analysis of the lanthanide induced shifts in the 31P NMR spectra indicated that the two structural types persist in solution. Changes in conductivity are consistent with the observed changes in structure across the lanthanide series. [Copyright &y& Elsevier]

The complex formation equilibria involving trans-diamminepalladium(II) chloride (Pd), 1,6-hexanediamine (HDA), and DNA constituents were investigated. The formation constant of all possible mononuclear and binuclear complexes were determined at 25 °C and 0.1 mol⋅L NaNO. The speciation diagrams of the binuclear complex of Pd-HDA-DNA reveal that these complexes predominate in the physiological pH range and the reaction of the binuclear complex Pd-HDA-Pd with DNA constituents is quite feasible. [ABSTRACT FROM AUTHOR]

Treating the phenylvinyldene manganese complex Cp(CO)2Mn=C1=C2HPh, 1, with [Fe(CO)4] yields the binuclear μ-vinylidene complex Cp(CO)2MnFe(μ-C1=C2HPh)(CO)4, 2, that further isomerizes to the carbonylated product η4-[Cp(CO)2MnC1(CO)C2HPh]Fe(CO)3, 3. In a computational study of the mechanism using a hybrid density functional method, we considered two stereoisomers for species 2 and 3 where the phenyl group at center C2 is oriented in cis (E form) or trans (Z form) fashion to the Cp(CO)2Mn unit. Isomers 2E and 2Z were calculated to be degenerate whereas the experimentally detected species 3E is 8 kcal/mol more stable than its isomer 3Z. The two-step pathway 1 → 2Z → 3E was calculated to be the lowest-energy route with the highest activation barrier at 12 kcal/mol. The activation energy of the alternative single-step pathway 1 → 3E is 19 kcal/mol. We rationalized the stabilization of the ground state of 3E and the transition states leading to or starting from isomer 2Z as conjugation effect between the Mn–C=C metallaallene fragment and the co-planar phenyl ring. [Copyright &y& Elsevier]

Abstract: Two binuclear iron(III) complexes, [L1FeIII(bpy)FeIIIL1](BPh4)2 (1) and [L2FeIII(bpy)FeIIIL2](BPh4)2 (2), were synthesized and characterized, where H2L1 and H2L2 denote bis(salicylicdeneaminopropyl)methylamine and bis(3-methoxysalicylideneaminopropyl)methylamine, respectively, and bpy denotes 4,4′-bipyridine and BPh4 − denotes tetraphenylborate. Complexes 1 and 2 consist of one and two crystallographically unique Fe sites, respectively, while they have a similar binuclear complex-cation [L n FeIII(bpy)FeIIIL n ]2+ (n =1, 2) bridged by 4,4′-bipyridine and two tetraphenylborate ions as the counter anions. The magnetic susceptibility measurements of 1 and 2 showed one-step and two-step spin crossover (SCO), respectively. The four saturated six-membered chelate rings at the aminopropyl moieties of 1 exhibit disorder throughout one-step SCO. The two chelate rings of one Fe site of 2 exhibit disorder but the other two of another Fe site do not. The different SCO behaviors of 1 and 2 were ascribed to one and two crystallographically unique Fe sites and the order/disorder at the saturated six-membered chelate rings of aminopropyl moieties. [Copyright &y& Elsevier]

Abstract: The reactions of Co(O2CCH3)2·4H2O with the sodium salt of p-toluene sulfonic acid (NapTS) and pyridine (py) or 4-methylpyridine (4mepy) in the presence of hydrogen peroxide in methanol led to the formation of [Co(py)3(H2O)3](pTS)2 or [Co(4mepy)2(H2O)4](pTS)2·MeOH, respectively. The coordination polymer [{Co(44′bpy)(H2O)4}(pTS)2] n (4,4′-bipyridine=44′bpy) was obtained from the reaction of Co(O2CCH3)2·4H2O with 44′bpy in the presence of NapTS. The reaction of Co(O2CCH3)2·4H2O, 2,2′-bipyridine (22′bpy) and NapTS with hydrogen peroxide resulted in the formation of the dinuclear complex [Co2(μ-OH)2(μ-O2CCH3)(O2CCH3)2(22′bpy)2](pTS). Characterization of these complexes and the role of hydrogen peroxide in these reactions are discussed. Similar reactions with sodium sulfamate gave the mononuclear [Co(22′bpy)2(O2CCH3)]NH2SO3·2H2O complex and [Co2(μ-OH)2(μ-O2CCH3)(O2CCH3)2(22′bpy)2](NH2SO3). [Copyright &y& Elsevier]

Abstract: Binuclear cyanate bridged nickel(II) complex [Ni(L)(NCO)]2(PF6)2 (1) and copper(II) complex [Cu(L)(NCO)]2(PF6)2 (2), where L is N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)aminomethylpyridine, a tetradentate N4-coordinated ligand have been synthesized and characterized by physicochemical method. The structures of complexes 1 and 2 have been studied by single crystal X-ray diffraction analysis. The structure analysis reveals that both nickel(II) and copper(II) center are coordinated in distorted octahedral fashion and coordination mode of cyanate ligand is end-to-end (μ-1,3) for complex 1 but it is double end-on (μ-1,1) mode for complex 2. The variable temperature magnetic susceptibility data, measured from 2 to 300K, show weak antiferromagnetic interaction with J value −6.2(1)cm−1 for complex 1, whereas complex 2 has very weak ferromagnetic interaction with J value +0.5(1)cm−1. [Copyright &y& Elsevier]

Crystal structures of two modifications of a binuclear Pd(μ-ac)(acac) complex are studied at 150 K and 297 K (ac = acetate; acac = acetylacetonate). It is demonstrated that in both cases, the packing of the complexes can be considered as pseudohexagonal, the molecules forming infinite chains by interactions between chelate rings with the shortest contacts Pd...C ∼ 3.3 Å. [ABSTRACT FROM AUTHOR]

Abstract: Three complexes of composition [Co2 IICo2 III(H2hbhpd)2(H4hbhpd)2(H2O)2]Cl2(CH3OH)4 (1), [Co2 IICo2 III(H2hbhpd)2(H4hbhpd)2(H2O)2](NO3)2(CH3OH)4 (2) and [Ni2(H4hbhpd)2(NO3)](NO3)(CH3OH)1.5 (3) (H5hbhpd=2-(2-hydroxy-benzylamino)-2-hydroxymethyl-propane-1,3-diol) have been synthesized and their structures have been characterized. Complexes 1 and 2 are mixed-valence cobalt clusters and display face-sharing monovacant dicubane structures. In the complexes 1 and 2, one of the three alkyl hydroxyl groups of H5hbhpd ligand is deprotonated instead of deprotonation of phenyl hydroxyl group; thus monoanionic H4hbhpd− ligand displays novel η3, η1, η1, μ3 coordination mode. Complex 3 is binuclear, and the two metal centers of 3 are bridged by two deprotonated phenyl hydroxyl oxygen atoms and iso-orthogonalized by a nitrato group in η1η1-O,O′ coordination fashion. Variable-temperature solid-state dc magnetization studies have been performed in the temperature range 2–300K for compounds 1 and 3. Antiferromagnetic interactions were determined for 1 and ferromagnetic couplings were found for 3. [Copyright &y& Elsevier]

luminium and zinc complexes bearing the N,O-chelating Schiff base ligand 4,6-bis-1-(2-(dimethylamino)ethylimino)ethyl)benzene-1,3-diol, (CH(OH)(NCHCHNMe)) ( 1a), have been synthesized. Bimetallic aluminium and zinc alkyl complexes ( 2a- 4a) were prepared by treatment of the hexadentate 1a with the appropriate amount of AlMe, ZnMe and ZnEt, respectively. 2a has been characterized crystallographically, it lies on a crystallographic two-fold rotation axis and each aluminium centre adopts a five coordinate geometry. Complex 2a was tested as a catalyst in the ring-opening polymerisation of ɛ-caprolactone. We describe here the synthesis of two neutral ligands ( 1a and (CH(OH)(CHNH) (C=O(CH)) ( 1b)) and demonstrate their application in the synthesis of molecular aluminium and zinc derivatives. [ABSTRACT FROM AUTHOR]

A mononuclear fragment [Cu(L)Cl]ClO ( 1) and a cyano-bridged Cu-Ni binuclear complex [CuL][Ni(CN)]·0.25HO ( 2) (L = 1,3,6,8,11,14-hexaazatricyclo[12.2.1.18,11]-octadecane), have been prepared and characterized. X-ray single crystal analyses indicate that the both complexes crystallize in the monoclinic crystalline system. The complex of 1 in P1 n1 space group with unit cell constants a = 6.1176(6) Å, b = 11.9147(10) Å, c = 12.2041(12) Å, β = 98.816(5)° and 2 in the P2/ n space group with unit cell constants a = 8.1419(13) Å, b = 14.695(2) Å, c = 16.863(3) Å, β = 98.375(2)° have been revealed. The complex 2 assumes a binuclear structure in which the nickel(II) ion is in a square planar environment and the copper(II) is in a square-prism geometry environment. Graphical Abstract: A novel Cu-Ni bimetallic assembly constructed from Cu macrocyclic ligand and [Ni(CN)] anion.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: The present work reports the chemistry of a few oxidovanadium(IV) and (V) complexes of the ONS chelating ligand S-benzyl-β-N-(2-hydroxyphenylethylidine) dithiocarbazate (H2L). Major objective of this work is to arrive at some general conclusions about the influence of binding environment generated by the replacement of an O-donor center by a S-donor point in a ligand (of a similar arrangement of the other O- and N-donor points) on the redox behavior and on the structural features of comparable [VO(OEt)(ONS)] and [VO(OEt)(ONO)] complexes. Synthesis, characterization by various physicochemical techniques (UV–Vis, IR, EPR and elemental analysis), exploration of electrochemical activity of the oxidovanadium(V) complex [VVO(OEt)L] (1), the mixed ligand complex [VVO(N–O)L] (3) (where N–O is the mono anion of 8-hydroxyquinoline) and a binuclear complex [VVO(OEt)L]2(μ-4,4′-bipy) (2) are reported. Similar studies on of mixed ligand oxidovanadium(IV) complexes of the formula [VVO(N–N)L] (4,5) (where N–N=2,2′-bipy and o-phen) are also presented here. The [VVO(OEt)L] complex is pentacoordinated and distorted square pyramidal, while the [VIV(N–N)L] complexes are hexacoordinated and octahedral. Structural features of the complex 1 were compared with the corresponding aspects of the previously reported analogous complex [VVO(OEt)(ONO)] (1′). [ABSTRACT FROM AUTHOR]

Polydentate ligands 2-[(2-hydroxypropylimino)methyl] phenol (L) and pyridine-2,6-dicarboxylic acid (H2pda) have been used in the synthesis of binuclear transition metal complexes. A new doubly end-on azido-bridged binuclear nickel(II) complex with formula [ [image omitted](µ1,1-N3)2(L)2(N3)2] · H2O (1) and a bis-µ-hydroxo-bridged dinuclear chromium(III) complex with the formula [ [image omitted](OH)2(pda)2(H2O)2] (2) have been synthesized and characterized by single crystal X-ray diffraction and magnetic studies. Compound 1 displays intramolecular intermetallic ferromagnetic coupling with J = 28.32 cm-1 and D = -19.30 cm-1 based on the Hamiltonian H = -2JS1S2 - D( [image omitted]+ [image omitted]) - gβH(S1 + S2). Compound 2 displays intramolecular intermetallic antiferromagnetic coupling with J = -6.56 cm-1 based on the Hamiltonian H = -2JS1S2 - j(S1S2)2. [ABSTRACT FROM AUTHOR]

Abstract: A family of four new phenoxo-bridged binuclear manganese(III) complexes of the general formula, [Mn(L)(X)]2 where L=[N,N′-bis(salicylidene)]propane-1,2-diamine and X=salicylaldehyde anion (sal−) (1); NCS− (2); NCO− (3) and [Mn(L′)(N3)]2·2C2H5OH (4) where L′=[N,N′-bis(2-hydroxyacetophenylidene)]propane-1,2-diamine has been prepared. The syntheses have been achieved by reacting manganese perchlorate with 1,2-diaminopropane and salicylaldehyde (or 2-hydroxyacetophenone for 4) or along with the respective pseudohalides so that the tetradentate Schiff base H2L or H2L′ is obtained in situ to bind the Mn(III) ion. The complexes have been characterized by IR spectroscopy, elemental analysis, crystal structure analysis and variable-temperature magnetic susceptibility measurements. The single crystal X-ray diffraction studies show that the compounds are isostructural containing dimeric Mn(III) units with bridging phenolate oxygen atoms. Low temperature magnetic studies indicate that the complexes 1–3 exhibit intradimer ferromagnetic exchange as well as single-molecule magnet (SMM) behavior while complex 4 is found to undergo an intradimer antiferromagnetic coupling. [Copyright &y& Elsevier]

A compound with the composition Nd(C6F5COO)3· H2O (I) is prepared. Single crystals are grown, and their single crystal XRD analysis of the Nd2(H2O)8(C6F5COO)6]·2H2O (II) compound is performed. The crystals are triclinic: a = 7.693(2) Å, b = 9.394(2) Å, c = 18.203(4) Å, α = 81.91(3)°, β = 84.41(3)°, γ = 88.97(3)°, Z = 1, dx = 2.223 g/cm3. The structure is composed of symmetrical molecules of the binuclear [Nd2(H2O)8(C6F5COO)6] complex and crystallization water molecules. The C6F5COO- ligands are monodentate and tridentate bridging- chelating, which results in a closure of two four-membered chelate cycles NdO2C and a four-membered metal cycle Nd2O2. The NdO9 polyhedron is a distorted one-capped tetragonal antiprism. [ABSTRACT FROM AUTHOR]

Abstract: New methylnaphthalene-linked imidazolium salts 1 were synthesized through the reaction of 1,8-dibromomethylnaphthalene and N-alkylimidazole. On treatment of imidazolium salt 1 with silver oxide followed by [Cp∗MCl2]2 (M=Ir, Rh), binuclear iridium and rhodium complexes 2 were formed. Reaction of these complexes 2 with AgPF6 afforded Cl-bridged cationic binuclear iridium and rhodium complexes 3. X-ray crystallographic analysis of 3 revealed that the two imidazole rings of the carbene ligand are in a parallel geometry. The cationic binuclear iridium complexes 3-Ir could be applied to the intramolecular hydroamination reaction of 2-ethynylaniline to give the corresponding indole compound. [Copyright &y& Elsevier]

A series of new binucleating CoII, NiII, CuII, and ZnII complexes of bicompartmental ligands with SNO donors was prepared. The Schiff bases were obtained by the condensation of 4,6-diacetylresorcinol and mercapto-substituted 1,2,4-triazoles. The ligands and their complexes were characterized by elemental analysis, infrared, 1H-NMR, UV-Vis, FAB-mass, and ESR spectral studies, magnetic susceptibility, and conductivity measurements. All the complexes were monomeric and binuclear. NiII and CoII complexes were octahedral, whereas CuII and ZnII complexes were square planar and tetrahedral, respectively. The compounds are investigated for electrochemical activity. [ABSTRACT FROM AUTHOR]

Ten new binuclear singly oxo-bridged molybdenum complexes (complexes 1–10) were prepared using five pyrimidine derived Schiff base ligands and two Mo(V) precursors (NH4)2MoOCl5 and (NH4)2MoOBr5. The ligands are prepared by the condensation of 4,6-dimethyl 2-hydrazino pyrimidine with salicylaldehyde (for HL1), o-hydroxy acetophenone (for HL2) and substituted salicylaldehydes (for HL3, HL4 and HL5) respectively. These ligands are already reported as good donors for Mo(VI) state. The µ-oxo Mo(V) complexes reported here bears a distorted octahedral geometry around each Mo atom with either N2O2Cl or N2O2Br chromophores. Fine variations in the spectroscopic behaviour of the complexes are observed in accordance with the varying electron donating properties of the ligands. All the complexes are unstable in solution and X-ray quality crystal of complex 1 could be isolated. All the complexes are characterized by IR and UV-Vis spectra. [ABSTRACT FROM AUTHOR]

Abstract: A series of cyanide-bridged binuclear complexes, (‘S3’)Ni–CN–M[TptBu] (‘S3’=bis(2-mercaptophenyl)sulfide, TptBu =hydrotris(3-tert-butylpyrazolyl)borate, M=Fe (2-Fe), Co (2-Co), Ni (2-Ni), Zn (2-Zn)) was prepared by the coupling of K[(‘S3’)Ni(CN)] with [TptBu]MX. The isostructural series of complexes was structurally and spectroscopically characterized. A similar coupling strategy was used to synthesize the anionic copper(I) analogue, Et4N{(‘S3’)Ni–CN–Cu[TptBu]}, 2-Cu. An alternative synthesis was devised for the preparation of the linkage isomers of 2-Zn, i.e. of cyanide-bridged linkage isomers. X-ray diffraction, 13C NMR and IR spectral studies established that isomerization to the more stable Ni–CN–Zn isomer occurs. DFT computational results buttressed the experimental observations indicating that the cyanide-bridged isomer is ca. 5kcal/mol more stable than its linkage isomer. [Copyright &y& Elsevier]

Abstract: The reaction between Co(II) and the deprotonated tetraphenylimidodiphosphinic acid, [(OPPh2)2N]−, afforded a binuclear [Co2{(OPPh2)2N}4] complex, as revealed by X-ray crystallography. The structure contains two monometallic biconnective [(OPPh2)2N]− ligands, with an averaged Co−O bond length of 2.008Å. The other two [(OPPh2)2N]− act as bimetallic triconnective ligands, forming two oxygen atom bridges, with the four Co−O(bridging) distances averaged at 2.155Å, and the two Co−O(non-bridging) distances at 1.973Å. The two approximately trigonal bipyramidal Co(II) ions are at a Co⋯Co distance of 3.301Å. The analysis of the magnetic properties of [Co2{(OPPh2)2N}4] is consistent with an unusual ferromagnetic interaction, in a binuclear Co(II) system, between the two S =3/2 Co(II) ions. [Copyright &y& Elsevier]

A series of mono- and dinuclear gold(I) phosphine complexes of the type [Au{SeC(OMe)＝NPh}(P)] [P = PPh3, PTA, P(o-tolyl)3, P(p-MeOC6H4)3] and [Au2{SeC(OMe)＝NPh}2(μ-PP)] (PP = dppm, dppe, dppp, dppf, dppee) were prepared from the reaction of the appropriate chlorogold(I) phosphine complexes with N-phenyl-O-methylselenocarbamide in the presence of base. These new complexes were fully characterised by spectroscopic techniques and, in several cases, by X-ray crystallography. The differences in the solid-state structures of these selenium complexes were compared with those of some sulfur analogues. [Copyright &y& Elsevier]

Abstract: A new phenoxo-bridged binuclear manganese(III) Schiff base complex, [Mn(L)(N3)]2 (1) where L= N,N′-bis(salicylidene)-1,2-propanediamine has been synthesized and characterized by IR, elemental analysis, crystal structure analysis and variable temperature magnetic susceptibility measurements. The single crystal X-ray diffraction reveals that the structure is dimeric with each phenolate oxygen atom acting as a bridge between two symmetry equivalent Mn atoms. Low temperature magnetic study shows that the complex exhibits intra-dimer ferromagnetic exchange and single-molecule-magnet (SMM) behavior as well. [Copyright &y& Elsevier]

Abstract: The reactions of phosphorus ylide (p-tolyl)3PCHC(O)CH3 (Y 1) with HgX2 (X=Cl and Br) and (p-tolyl)3PCHC(O)C6H4NO2 (Y 2) with HgX2 (X=Cl, Br and I) in equimolar ratios using methanol as a solvent are reported. These reactions led to binuclear complexes. C-Coordination of ylides and trans-like structure of complexes [(Y1)·HgBr2]2 and [(Y2)·HgBr2]2 ·2DMSO are demonstrated by single crystal X-ray analyses. The IR, 1H, 13C and 31P NMR data for the other synthesized compounds are similar to the latter complexes, indicating similar structures. Elemental analyses indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in all the products. The ab initio studies indicated that for all dimeric compounds, the observed trans-like structures are 7–10kcal/mol more stable than the alternative possible cis-like isomers. Although the calculated bond lengths are slightly longer than the measured ones, the similarity of calculated and measured bond angles reflects the similar geometrical structures for these compounds in both the solid state and the gas phase. [Copyright &y& Elsevier]

The thermal decomposition of Mannich base N,N′-tetra(4-antipyrylmethyl)-1,2-diaminoethane (TAMEN), and its Ni(II), binuclear complex, Ni2(TAMEN)Cl4, in air and in nitrogen atmosphere, were investigated. X-ray powder diffractometry, infrared spectroscopy and simultaneous thermogravimetry-differential thermal analysis (TG-DTA), have been used to characterize and to study the thermal behavior of these compounds. The results provided information concerning the stoichiometry, crystallinity, thermal stability and decomposition mechanism of the compound. [ABSTRACT FROM AUTHOR]

The thermal decomposition in air and in nitrogen atmosphere of binuclear complex compounds of Cu(II) and Co(II) containing the Mannich base N,N′-tetra(4-antipyrylmethyl)-1,2 diaminoethane (TAMEN) as a ligand, Cu2(TAMEN)Cl4 and Co2(TAMEN)Cl4, were investigated. X-ray powder diffractometry, infrared spectroscopy and simultaneous thermogravimetry-differential thermal analysis (TG-DTA), have been used to characterize and to study the thermal behavior of these compounds. The results provided information concerning the stoichiometry, crystallinity, thermal stability and decomposition mechanism of the compounds. [ABSTRACT FROM AUTHOR]

Abstract: A new synthetic binuclear nickel(II) compound ([Ni2(tacud)2(μ-H2O)(μ-Cl)2]Cl2 (1); tacud=1,4,8-triazacycloundecane) is reported. Compound 1 contains two Ni(II) ions bridged by two chloro and one aqua ligand resulting in a short Ni···Ni distance of 3.0187(10)Å. Each nickel is capped by terminal tacud ligands and possesses distorted octahedral geometry. This compound exhibits a new structural motif for metal complexes supported by tacud. Compound 1 exhibits two solvent dependent transitions in the UV–vis spectrum. Variable temperature SQUID magnetic susceptometry studies on 1 indicate mild ferromagnetism exists at room temperature (μ eff =4.78μB) which increases upon temperature lowering. Magnetic analysis of 1 in the temperature range 2–300K confirm weakly ferromagnetic behavior with J =+2.28cm−1. [Copyright &y& Elsevier]

Abstract: The synthesis of a series of binuclear zinc complexes with Cl, N and O bridges is reported. The reaction of EtZnCl with B(C6F5)3 in the presence of hexamethylbenzene affords the arene complex [Zn(μ-Cl)(C6F5)(η-C6Me6)]2 in which the C6Me6 ligand may be regarded as η3-bonded. The comproportionation of Zn[N(SiMe3)2]2 with ZnBu t 2 or Zn(C6F5)2 ·toluene gave [Bu t Zn{μ-N(SiMe3)2}]2 and [C6F5Zn{μ-N(SiMe3)2}]2, respectively, with three-coordinate zinc. The reaction of ZnEt2 with C6F5OH in the presence of pyridine gave [EtZn(μ-OC6F5)(py)]2, while ZnMe2 and C6F5OH followed by recrystallisation from THF gave [Zn(OC6F5)(μ-OC6F5)(THF)2]2 with five-coordinate zinc in a trigonal-bipyramidal geometry. The structures of these compounds have been determined. [Copyright &y& Elsevier]

Infrared and visible light irradiation effects on the spin state of iron(II) ions have been investigated in the binuclear molecules {[Fe(bt)(NCSe)](bpym)} ( 4) and {[Fe(bpym)(NCSe)](bpym)} ( 2). For compound 2 we could observe LIESST and partial reverse-LIESST effects under visible and infrared light irradiation, respectively. Compound 4 exhibits a wavelength-selective photoconversion at 10 K from the low spin (LS-LS) ground state of the binuclear molecule to the metastable high spin (HS-HS) state under visible (785 or 532 nm) light irradiation or to the metastable HS-LS state under infrared (1,342 nm) light irradiation. In addition we also observed the reverse (HS-HS → HS-LS) and the cascade (LS-LS → HS-LS → HS-HS) photoconversions as well. These phenomena lead to complex and original photomagnetic behaviour due to the intramolecular magnetic coupling. [ABSTRACT FROM AUTHOR]

Two new binuclear complexes, [Mn2(μ-dmpo)2(SCN)4(H2O)2] (1) (where dmpo = 3,5-dimethylpyridine N-oxide), [Mn2(μ-po)2(H2O)6I2]I2 (2) (where po = pyridine N-oxide), have been synthesized and their crystal structures determined by X-ray crystallography. Complexes 1 and 2 crystallize in monoclinic, space group P21/c, with unit cell dimensions a = 8.8836(18) Å, b = 15.450(3) Å, c = 15.484(3) Å, β = 91.020(3)° for 1, and a = 8.8352(13) Å, b = 17.927(3) Å, c = 8.3338(12) Å, β = 103.765(2)° for 2. In each binuclear complex two Mn(II) were bridged by two 3,5-dimethylpyridine N-oxides or by two pyridine N-oxides and the distances between the bridged Mn(II) ions are 3.599 Å for 1 and 3.552 Å for 2. Variable temperature (4-300 K) magnetic measurements were performed for 1 and the susceptibility data were fitted by using a binuclear Mn(II) magnetic coupling formula producing the 2J = -2.17 cm-1. [ABSTRACT FROM AUTHOR]

Abstract: Large bite bisphosphite ligand, 2,6-C5H3N{CH2OP(–OC10H6)(μ-S)(C10H6O–)}2 (2), is obtained by reacting chlorophosphite, {-OC10H6(μ-S)C10H6O-}PCl (1) with 2,6-pyridinedimethanol in presence of triethylamine.Treatment of 2 with aqueous solution of H2O2 or elemental sulfur resulted in the formation of bis(oxide) or bis(sulfide) derivatives, 2,6-C5H3N{CH2OP(E)(–OC10H6)(μ-S)(C10H6O–)}2 (3, E=O; 4, E=S) in quantitative yield.The 10-membered cationic chelate complex, [RuCl(η6-C10H14)η2-2,6-C5H3N{CH2OP(–OC10H6)(μ-S)(C10H6O–)}2-κP,κP]Cl (5) is produced in the reaction between [Ru(p-cymene)(μ-Cl)(Cl)]2 and bisphosphite 2, whereas the neutral chelate complex, cis-[Rh(CO)Cl{2,6-C5H3N{CH2OP(–OC10H6(μ-S)C10H6O–)}2}-κP,κP] (6) is isolated in the reaction of 2 with 0.5 equiv.of [Rh(CO)2Cl]2.Compound 2 on treatment with M(COD)Cl2 (M=Pd, Pt) produce the chelate complexes, [MCl2{η2-2,6-C5H3N{CH2OP(–OC10H6)(μ-S)(C10H6O–)}2}-κP,κP] (7, M=Pd;10, M=Pt).Similarly the reaction of bisphosphite 2 with Pd(COD)MeCl affords cis-[PdMe(Cl)η2-2,6-C5H3N{CH2OP(–OC10H6)(μ-S)(C10H6O–)}2-κP,κP] (8).Treatment of 2 with [Pd(η3- C3H5)Cl]2 in the presence of AgClO4 furnish the cationic complex, [Pd(η3-C3H5)η2-2,6-C5H3N{CH2OP(–OC10H6)(μ-S)(C10H6O–)}2-κP,κP]ClO4 (9). The binuclear complex, [Au2Cl2{2,6-C5H3N{CH2OP(–OC10H6)(μ-S)(C10H6O–)}2}-κP,κP] (11) is obtained in the reaction of compound 2 with two equiv. of AuCl(SMe2), where the ligand exhibits bridged bidentate mode of coordination. All the complexes are characterized by the 1H NMR, 31P NMR, elemental analysis and mass spectroscopy data. The cationic ruthenium complex 5 is proved to be an active catalyst for the hydrogenation of styrene and α-methyl styrene. [Copyright &y& Elsevier]

Abstract: From the reaction of tribenzo-S2O2 macrocyclic ligand (L 1) and silver picrate (AgPic), a unique binuclear complex [Ag2(L 1)2(Pic)2] (1) has been obtained. The species 1 has been characterised by single-crystal X-ray diffraction analysis providing a definitive proof of its cyclic dimer structure as well as the anion–ligand π–π stacking interactions between L 1 and Pic−. The result of a comparative NMR experiment suggests that the solid structure of 1 is also retained in solution. [Copyright &y& Elsevier]