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

Abstract

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.

Synthesis and Structural Diversity of Four Coordination Polymers with the Ligand 1‐(3‐Aminopropyl)‐imidazole

“…The api ligand acts as bridge to join adjacent Cu II atoms to form 1D double chain structure (Figure 2b), which are further connected with the support of C4–H ··· O3, C6–H ··· O1 and N1–H ··· O4 hydrogen bonds (perchlorate anion) to form the final 3D structure (Figure S2c). Similar structures with flexible ligands like bis(1‐imidazolyl)methane have been studied by Pettinari et al12 For example, 1D double chain structure was obtained with the Cd II atom showing pseudooctahedral geometry environment, and the axial positions are two mono‐coordinated oxygen atoms from two acetate anions, etc 12a…”

Anion triggered and solvent assisted structural diversity and reversible single-crystal-to-single-crystal (SCSC) transformation between 1D and 2D coordination polymers

“…Furthermore, these PF 6 − ions are held within the loop through anion-π interactions between F9 and F12 and the pyridine rings (Fig. 43,44 In the 2D double helix, the Cd⋯Cd distances are 9.36(9) Å and 9.50(8) Å. Similar to that in 1, the C-N bond rotation in 2 results in deviation of one of the imidazole rings from the plane of the pyridine ring with an interplanar angle of 21.00IJ2)°.…”

Crystal structure of 1,1-bis[(2-phenylazo)imidazol-1-yl]methane, C19H16N8

“…Recently, some inorganic-organic hybrid compounds based on the ligand bis(imidazol-1-yl)methane have been documented [3,4]. The crystal structure analysis shows that there are two phenylazoimidazole moieties in an asymmetric unit.…”