Phosphinobenzyl- and aryl-silanes and their triosmium cluster carbonyl derivatives
Abstract
The Grignard reagents MgR(Br)(R = C6H4CH2SiMe2H-o or C6H4CH2SiMeH2-o) have been found to undergo unusual reactions with Ph2PCl to afford o-Ph2PC6H4CH2SiMe2H I and o-HMe2SiC6H4CH2PPh2II and o-Ph2PC6H4CH2SiMeH2III and o-H2MeSiC6H4PPh2IV respectively. Reactions of the respective bidentate ligands I, II, III and IV with [Os3(CO)10(MeCN)2] gave the novel triosmium cluster [Os3(µ-H)(CO)10(L–L)]1, 2, 3 and 4 involving cleavage of one Si–H bond. Similar reactions of ligands II and IV with [Os3(µ-H)2(CO)10] afforded two new clusters [Os3(µ-H)3(CO)8(L–L)]5 and 6 respectively. The structures of 1, 2, 4 and 5 have been determined by single-crystal X-ray diffraction techniques. In each case, the ligand assumes a chelating mode across the long edge of the osmium triangle which is also bridged by a hydride. The high-performance liquid chromatographic behaviour of these clusters has also been determined and correlated with the size and nature of the ligands.