Some Group 15 pseudo-halides and the crystal structure of diphenylbismuth(III) thiocyanate

A crystal structure determination showed that in diphenylbismuth thiocyanate the thiocyanate group bridges between pairs of bismuth atoms to give infinite chains in which alternate bismuth atoms are co-ordinated to either two nitrogen or two sulfur atoms. The conformation of the resulting chain is a ‘rectangular spiral’, in contrast to the ‘triangular spiral’ structure of the related diphenylantimony thiocyanate. Unstable diphenylantimony selenocyanate has also been prepared and the complexity in the C–N stretching region of the IR spectrum suggests a structure similar to that of the thiocyanate analogue. Diphenylarsenic thiocyanate is a liquid at room temperature and a conventional 1,3-thiocyanate-bridged structure is suggested from IR data.