Bim Ligands Research Articles

Syntheses and Crystal Structures of Two Chloro‐Bridged Coordination Polymers [Cd(BIM)Cl2]n and [Pb(BIM)Cl2]n

AbstractTwo novel coordination polymers, [Cd(BIM)Cl2]n (1) and [Pb(BIM)Cl2]n (2) [wherein BIM = bis(imidazol‐1‐yl)methane], were synthesized by the reactions of the BIM ligand with CdCl2 and PbCl2, respectively. They were characterized by elemental analyses, IR, TGA and X‐ray single‐crystal diffraction techniques. Single‐crystal X‐ray structure analyses showed there is a pseudooctahedral arrangement around the cadmium atom in the complex 1. It has a three‐dimensional network which contains one‐dimensional inorganic‐organic hybrid chains and μ2‐bridging chloride ligands. A rare pentacoordinate square‐pyramidal arrangement was adopted for the lead(II) atom in the complex 2, which has an unusual two‐dimensional layer structure of macrometallacycles crosslinked with the bridging Pb2Cl2 units. The metal atoms in both complexes were coordinated with two BIM ligands in cis arrangement and bridged by μ2‐bridging chloride ligands.

Two novel coordination polymers with different molecular tectonics based on zinc nitrate and bisimidazole ligand

Two new coordination polymers, [Zn(2-mBIM) 2(NO 3) 2(H 2O) 2] n ( 1) and [Zn(BIM) 2(NO 3) 2(H 2O) 2] n (2) (2-mBIM = bis(2-methylimidazol-1-yl)methane, BIM = bis(imidazol-1-yl)-methane), were synthesized by the reactions of Zn(NO 3) 2 with 2-mBIM and BIM ligands. They were characterized by elemental analyses, IR, TGA and X-ray single-crystal diffraction techniques. Each of metal centers in 1 and 2 is coordinated in a slightly distorted tetrahedral geometry by four aromatic nitrogen atoms from four distinct 2-mBIM or BIM ligands, respectively. In compound 1, each pair of neighboring Zn II centers is bridged by two 2-mBIM ligands to form a 16-membered macrometallacyclic structural motif. Each 2-mBIM ligand is coordinated to two Zn II cations and acts as a bridged ligand to form a one-dimensional polymeric cationic chain structure. Compound 2 has a 2D network structure containing 1D channel, thereby each BIM ligand is coordinated to two Zn II cations and thus acts as a bridging ligand. Moreover, each group of four BIM ligands is linked alternatively to each other by four Zn II cations, resulting in a 32-membered macrometallacycle.

A series of metal–organic complexes constructed from in situ generated organic amines

A series of hydrothermal reactions of metallic salts (CoCl2, CdSO4 and ZnCl2), carboxylates (oxalic acid and 1,4-H2BDC) and organic amines (o-PD, Him) have been investigated. Five coordination complexes, [Zn2(bim)4]n (1), Cd(H2bbim)2SO4·1/3(H2O) (2), [Co2(H2bbim)4(bbim)]Cl2 (3), [Co(Hbim)(Him)(C2O4)]n (4) and [Zn(H2bbim)(1,4-BDC)]n (5) (o-PD = o-phenylenediamine, Hbim = benzimidazole, H2bbim = 2,2′-bisbenzimidazole, Him = imidazole, 1,4-H2BDC = 1,4-benzenedicarboxylic acid), were prepared and characterized by elemental analyses, IR, single-crystal X-ray diffraction, fluorescence and magnetic analyses. Interestingly, two different ligands Hbim and H2bbim were generated via hydrothermal in situ reactions of o-PD and oxalic acid during the formation processes of these compounds. In 1, bim ligands bridge each pair of Zn atoms into a single-stranded helical chain through metal–ligand interactions to generate a 2-D grid-like structure. Complex 2 features a mononuclear structure due to the large steric hinderance of H2bbim ligand. Through N–H⋯Cl hydrogen bonds, the dinuclear units of 3 are alternately arranged to afford a unique 1-D helical chain. Complex 4 exhibits a 1-D zig-zag chain which consists of [Co(Hbim)(Him)]2+ units bridged by oxalate ligands, and 5 displays a 1-D chain structure consisting of Zn(H2bbim)2+ units linked by 1,4-BDC ligands.

Structural and Thermodiffractometric Analysis of Coordination Polymers. Part I: Tin Derivatives of the Bim ligand [Bim = Bis(1-imidazolyl)methane

New polynuclear coordination species containing the ditopic bis(1-imidazolyl)methane (Bim) ligand have been prepared as microcrystalline powders and structurally characterized by ab initio X-ray powder diffraction methods. [Bim(Me2SnCl2)]n (1), [Bim(nBu2SnCl2)]n (3), [Bim(Ph2SnCl2)]n (4), [Bim(MeSnCl3)]n (5), and [Bim(PhSnCl3)]n (6) all contain 1D chains with octahedral tin atoms with trans N-Sn-N linkages (but 4, which displays a cis N-Sn-N linkage). Their thermodiffractometric analysis allowed the estimation of the linear thermal expansion coefficients and strain tensors derived there from. The potential-energy surface of the free Bim ligand (as defined by two torsional degrees of freedom about the two N-CH2 bonds), eventually controlling the length of the repeating unit (polymer elongation), has been estimated using molecular mechanics and correlated with experimental observations.

Structural and Thermodiffractometric Analysis of Coordination Polymers. Part II:1 Zinc and Cadmium Derivatives of the Bim ligand [Bim = Bis(1-imidazolyl)methane

New polynuclear coordination species containing the ditopic bis(1-imidazolyl)methane (Bim) ligand have been prepared as microcrystalline powders and structurally characterized by ab initio X-ray powder diffraction methods. [Zn(CH3COO)2(Bim)]n contains 1D chains with tetrahedral metal atoms bridged by Bim ligands; [CdBr2(Bim)]n shows a dense packing with hexacoordinated Cd(II) ions and mu-Br and mu-Bim bridges; at variance, the isomorphous [ZnCl2(Bim)]n and [ZnBr2(Bim)]n species contain cyclic dimers based on tetrahedral Zn(II) ions. Thermodiffractometric analysis allowed estimation of the linear thermal expansion coefficients and strain tensors derived there from. Bim-rich phases, with 2:1 ligand-to-metal ratio, were also isolated: ZnBr2(Bim)2(H2O)3 and [Cd(CH3COO)2(Bim)2]n containing cis and trans MN4O2 chromophores, respectively, show 1D polymers built upon M2Bim2 cycles, hinged on the metal ions. In all species the conformation of the Bim ligands is Cs (or nearly so), while in the few sparse reports of similar coordination polymers the alternative C2 one was preferentially observed.

Crystal and molecular structures of the organometallic species [Rh2(bim)2(cod)2]Cl2∙2H2O [bim=bis-(1-imidazolyl)methane; cod=1, 5-cyclooctadiene

The synthesis and X-ray powder diffraction data for the organometallic [Rh2(bim)2(cod)2]Cl2∙2H2O species are reported. Its crystal and molecular structures were determined by simulated annealing and full-profile Rietveld refinement methods. [Rh2(bim)2(cod)2]Cl2∙2H2O was found to crystallize in the orthorhombic Cmca space group. The lattice parameters were determined to be a=21.3574(6), b=10.7764(3), c=14.2795(4) Å, V=3286.5(2) Å3, for Z=4. The crystal structure was found to contain dimeric [Rh2(bim)2(cod)2]2+ cations, in which the bim ligands bridge Rh(cod) fragments with an intermetallic separation of ca. 8.90 Å. The crystal structure is completed by chloride ions and hydrogen-bonded water molecules, situated in the small cavities of the large cation substructure. The conformation of the bim ligand, lying on a crystallographic mirror plane, is rigorously Cs.

Poly[[bis(benzimidazole)manganese(II)]-di-μ-1,5-dicyanamido

In the crystal structure of the title complex, [Mn(C2N3)2(C7H6N2)2] n or [Mn(dca)2(bim)2] n , where dca is dicyanamide and bim is benzimidazole, each MnII atom is located on a center of symmetry and is in a six-coordinated distorted octahedral environment. Four N atoms from four dca ligands fill the equatorial positions, and two N atoms from two bim ligands occupy the axial positions. The dicyanamide ligands adopt an end-to-end coordination mode and link the Mn atoms to form a two-dimensional network.

A novel triple-stranded cadmium(II) polymer chain:catena-poly[cadmium(II)-μ-1,2-bis(imidazol-1-yl)ethane-κ2N3:N3′-di-μ-1,5-dicyanamido-κ4N1:N5

In the crystal structure of the title complex, [Cd(C2N3)2(C8H10N4)]n or [Cd(dca)2(bim)]n, where dca is dicyanamide and bim is 1,2-bis­(imidazol-1-yl)ethane, each CdII atom is in a distorted octa­hedral environment. Four N atoms from four dca ligands occupy the equatorial positions, and two N atoms from two bim ligands occupy the axial positions. Each CdII atom is situated at a center of symmetry, and a twofold axis runs through the mid-points of the bim exocyclic C—C bond and the Cd⋯Cd vector. The structure consists of chains in which neighboring CdII atoms are connected through one bim and two end-to-end dca bridges.

Synthesis and crystal structure of an infinite double- stranded chain manganese(II) coordination polymer bridged through 1,2-bis(imidazol-1-yl)ethane ligand

The manganese complex [Mn(bim)2(NCO)2] n (1) (bim = 1,2-bis(imidazol-1-yl)ethane) has been synthesized and structurally characterized by X-ray diffraction analysis. It crystallizes in the monoclinic space group C2/c, a = 9.896(3) A, b = 15.383(4) A, c = 13.949(4) A, β = 98.966(5)∘, V = 2097.5(9) A3, Z = 4. The coordination geometry of Mn(II) atom is distorted octahedral; it is coordinated equatorially by four nitrogen atoms from the imidazole rings of four symmetry-related bim ligands, and axially by two nitrogen atoms from two symmetry-related cyanate anions. The structure is polymeric, with 18-membered spiro-fused rings and each 18-membered ring involving two inversion-related bim molecules.

A novel two-dimensional Mn(II) coordination polymer with 1,2-bis(imidazol-1-yl)ethane.

In the crystal structure of the title complex, poly­[[di­azido­manganese(II)]-di-μ-1,2-bis­(imidazol-1-yl)­ethane-κ4N3:N3′], [Mn(N3)2(C8H10N4)2]n or [Mn(N3)2(bim)2]n, where bim is 1,2-­bis(imidazol-1-yl)­ethane, each MnII atom is six-coordinated in a distorted octahedral coordination environment to four N atoms from four bim ligands and two N atoms from two azide ligands. The MnII atoms, which lie on inversion centres, are bridged by four bim ligands to form a two-dimensional (4,4)-network. The azide ligands are monodentate (terminal).

Mixed-valence properties of Ruthenium–Polypyridine dimers bridged by Imidazolate and Triazolate Ligands

The dinuclear complex cis,cis-[(bpy)2ClRu(μ-bim)RuCl(bpy)2] n + (bpy = 2,2′-bipyridine; bim = benzimidazolate; n = 1, 2, or 3) was synthesized, isolated as a hexafluorophosphate salt, and investigated in organic solutions by cyclic voltammetry and UV/visible/NIR spectroelectrochemistry. The mixed-valent species (n = 2) displays significant metal–metal electronic coupling in the ground state but exhibits localized Ru(III) and Ru(II) oxidation states, as deduced from its intervalence charge transfer (IVCT) band and redox parameters. On the basis of the resonance energy (H AB) estimated in the context of Hush's semiclassical theory, the extent of intermetallic communication was found to be larger than that recently reported for the bta-bridged analog (bta = benzotriazolate). Some differences between the IVCT features of these systems have been rationalized in terms of the degree of σ,π-basic character of the bridging ligands, according to an electron superexchange mechanism of the “hole-transfer” type. The stabilization of the mixed-valent complexes is attributed mainly to cooperative metal-to-ligand/ligand-to-metal charge-transfer effects. The combined π-acceptor and σ,π-donor abilities of the ancillary (bpy) and bridging (bim or bta) ligands, respectively, are also responsible for the high stability of the fully oxidized (RuIII–L–RuIII) and fully reduced (RuII–L–RuII) isovalent species.

Absence of direct metal–nucleotide interaction in the crystal structure of the ternary system, [Cu(bim)(H2O)5]2+[5′-IMP]2–·3H2O (bim = benzimidazole; 5′-IMP = inosine 5′-monophosphate)

The unusual absence of direct metal-nucleotide binding in a metal-6-oxopurine nucleotide complex is demonstrated for the first time in the structure of $[Cu(bim)(H_2O)5]^{2+}[5'-IMP-.3]^{2-}3H_2O$ (bim = benzimidazole; 5'-IMP = inosine 5'-monophosphate); the nucleotide base stacks with the bim ligand and the phosphate oxygens are involved in hydrogen bonds with the co-ordinated water molecules.