HETEROMETALLIC CARBONYL CLUSTERS OF OS,IR,RU,FE AND RH WITH DIVALENT SN,PB AND GE AND THE BULKY LIGANDS -CH(SIME3)2, -C6H2(I-PR)3 AND -C6H2(PH)3. Christine J. Cardin, David J. Cardin,¹ and Maire A. Convery,² Chemistry Department,University of Reading, Whiteknights, Reading, RG6 6AD, U.K.,¹ Chemistry Department, Trinity College, Dublin 2, Ireland²

A comparative survey, including some unpublished work, of our structural studies on heterometallic clusters, principally those of Sn(II) with transition metal clusters, will be presented. All clusters have been synthesised in the authors' laboratory, and some have not previously been reported. We find that the SnR₂ moieties, R = -CH(SiMe₃)₂ , -C6H₂(i-Pr)₃ and -C₆H₂(Ph)₃ confer kinetic stability on a variety of metal frameworks, electron configurations and unusual geometries.

We also find that the nature of the ligand considerably influences the geometry adopted, and that there is both a characteristic 'bite' and 'twist' for each ligand. In a study of mixed-ligand ruthenium-tin clusters, a very consistent pattern of ligand influences was observed, in which the larger steric effect of the aryl ligand can be distinguished from the larger electronic effect of the alkyl ligand. Limited data are also available on Pb-Ru clusters and on Os-Sn clusters with Sn-amide ligands. Data have been collected using both diffractometer and image plate and a brief comparison of the data collections will be made.