Hydrogen bonded 2,2′-biimidazolate transition metal complexes as a tool of crystal engineering

In the field of crystal engineering, many attempts have been made to control the molecular arrangements in crystal by simultaneous use of coordination bonds of a transition metal ion and complementary intermolecular hydrogen bonds. We obtained the first crystal structure of the hydrogen bonded metal complex of 2,2'-biimidazolate monoanion ligand Hbim(-) with Cu(II) as a neutral dimer metal complex. The hydrogen-bonded dimer structure indicates that the Hbim(-) ligand controls the crystal structure using not only the coordination to a transition metal ion as a bidentate chelate but simultaneously the formation of complementary intermolecular hydrogen bonds. We also found that the Hbim(-) ligand gave [Ni(Hbim)(3)](-) as a new building block for hydrogen-bonded self-assembling networks by one-pot synthesis to mix Ni(II) ion, counter cation and the ligand. The networks form zero-dimensional, one-dimensional, two-dimensional, and three-dimensional structures depending upon the kind of counter cations. (C) 2000 Elsevier Science S.A. All rights reserved.