SOME GROUP-15 PSEUDO-HALIDES AND THE CRYSTAL-STRUCTURE OF DIPHENYLBISMUTH(III) THIOCYANATE

A crystal structure determination showed that in diphenylbismuth thioc yanate the thiocyanate group bridges between pairs of bismuth atoms to give infinite chains in which alternate bismuth atoms are co-ordinate d to either two nitrogen or two sulfur atoms. The conformation of the resulting chain is a 'rectangular spiral', in contrast to the 'triangu lar spiral' structure of the related diphenylantimony thiocyanate. Uns table diphenylantimony selenocyanate has also been prepared and the co mplexity in the C-N stretching region of the IR spectrum suggests a st ructure similar to that of the thiocyanate analogue. Diphenylarsenic t hiocyanate is a liquid at room temperature and a conventional 1,3-thio cyanate-bridged structure is suggested from IR data.