A green polymeric zinc(II) complex: Synthesis, structural characterization, and theoretical studies

Synthesis and X-ray structural characterization of a Zn(II) polymer [Zn(NCS) 2 (L)] n ( 1 ) [L = 4,4¢-bipyridine] have been reported. The compound, having a metal [Zn(II)] with d 10 electronic configuration at the centre of each monomeric unit, shows green colour (absorption band at 648 nm). Molecular orbital energy calculations (and the theoretical spectra obtained therefrom) using GAUSSIAN-09 program package show that HOMO-LUMO energy difference gradually decreases from monomeric to tetrameric units. On considering λ max to be 648 nm in the non-linear fit equation (λ max versus molecular units), it is found that 13 molecular units are responsible for the experimentally observed green color of 1 .