Synthesis and crystal structure of a zwitterionic nickel(II) complex

The crystal structure of complex 3, a Ni(II)(dppe) ligated in a square planar arrangement by a novel S, N-ligand, has been determined at 123 K. The neutral and air stable complex is of interest as it shows an apparently zwitterionic structure, one counter-anion to the Ni(II) being delocalised into the backbone of the ligand. Support for this conclusion comes from an analysis of bond lengths in the complex 3, the crystal structure of which is presented and the result of a density functional calculation performed on the complex. A discussion of the mechanism leading to the observed product is presented.