Synthesis and crystal structures of six thiocyanato-connected transition metal complexes of 2,2′-biimidazole

Six new complexes {[Cu(NCS)(H2biim)]2(μ-NCS)2}·DMSO (1), [Cu(H2biim)2(NCS)](SCN)0.5(NO3)0.5 (2), [M(H2biim)3][M(NCS)4]·3DMSO (3–6), (H2biim = 2,2′-biimidazole, DMSO = dimethyl sulfoxide, M = Cu, Co, Ni, Zn) have been synthesized and characterized by X-ray crystallography. In complex 1, two copper atoms are coordinated by the H2biim ligand and the isothiocyanate ion respectively and they are further bridged by isothiocyanate anions leading to a binuclear structure. Complexes 1, 3–6 are obtained in DMSO/H2O. Complex 2 is obtained in water. In complex 2, the SCN− anion coordinates to Cu(II) atoms with N atom, resulting in compound 2 with the square pyramidal geometry. Complexes 3–6 consist of [Δ-M(H2biim)3]2+ cations, [Λ-M(H2biim)3]2+ cations and [M(NCS)4]2− anions (M = Cu, Co, Ni, Zn). In the six complexes hydrogen bonds R21(7), N–H…O, N–H…S and S…S intermolecular interaction help to form one to two dimensional structures.

Graphical abstractSix complexes [Cu2(H2biim)2(NCS)4]·DMSO, [Cu(H2biim)2(NCS)](SCN)0.5(NO3)0.5, [M(H2biim)3][M(NCS)4]·3DMSO, (H2biim = 2,2′-biimidazole, DMSO = dimethyl sulfoxide, M = Cu, Co, Ni, Zn) have been synthesized and characterized by X-ray crystallography. In the six complexes hydrogen bonds R21(7), N–H…O, N–H…S and S…S intermolecular interaction help to form one to two dimensional structures.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Six thiocyanato-connected transition metal complexes of 2,2′-biimidazole were isolated and characterized. ► The hydrogen bonds R21(7), N–H…O, N–H…S and S…S intermolecular interaction help to form one to two dimensional structures. ► In the synthesis reactions of 1, 3–6, nitrate are substituted by thiocyanate, for complex 2 part of nitrate anions remain. ► The structures of compounds 3 and 4 are perhaps induced by template Zn2+ ion. ► In 3–6, the [M(NCS)4]2− anion helps the formation of the chiral building blocks [Δ-M(H2biim)3]2+ and [Λ-M(H2biim)3]2+.