Synthesis and structural studies of selenocyanato-bridged polymeric and molecular complexes of cadmium(II): presence of both end-to-end and end-on coordination

Two new complexes, having one two-dimensional zig–zag polymeric network [Cd2(dmen)2(SeCN)4]n (1) and one molecular packing structure [Cd(dmen)2(SeCN)2] (2) (where dmen=N,N-dimethyl ethylenediamine), have been synthesised and characterised by infrared spectra and single crystal X-ray diffraction study. The different arrangements of selenocyanate anions result in two dimensional zig–zag polymeric sheet with the formation of two different rings, one having an eight-membered nearly hexagonal ring and another having a pseudo 16-membered ring for 1 and a molecular complex 2 with four independent molecules, having a total of 16 molecules per cell. The coordination environment in both the complexes is distorted octahedral. In the selenocyanato-bridged polymeric complex the cadmium(II) ions are linked by end-to-end coordination whereas in the molecular complex the cadmium(II) ions are bridged by end-on coordination only.