geometry for all the tin atoms in both complexes, the two DPSO ligands being cis to each other and in the second complex the ethyl group being trans to one of the DPSO ligands. In the second complex, under the influence of the ethyl group lengthening of the cis SnI bonds by 0.06 Å and shortening of the trans SnO bond by 0.06 Å occur. The mutual dependence of the SnO and OS bond distances is noted