Osmium−Antimony Higher Nuclearity Clusters

Thermolysis of Os3(CO)11(SbPh3), 1, in refluxing octane gave initially the clusters Os3(μ-SbPh2)(μ-H)(μ3,η2-C6H4)(CO)9, 2, and Os6(μ3-SbPh)(μ3,η2-C6H4)(CO)20, 3. Prolonged heating gave the cluster Os6(μ4-Sb)(μ-H)(μ3,η4-C12H8)(μ3,η2-C6H4)(CO)16, 4, as the major product. In contrast, thermolysis in hexane at 115 °C in a Carius tube gave Os6(μ4-Sb)(μ-SbPh2)(μ-H)2(μ3,η4-C12H8)(μ3,η2-C6H4)(CO)15, 5, Os6(μ4-Sb)(μ-SbPh2)(μ-H)(μ3,η2-C6H4)2(C6H5)(CO)16, 6, and Os6(μ4-Sb)(μ-SbPh2)(μ-H)(μ3,η6-C6H4)(μ3,η2-C6H4)(C6H5)(CO)15, 7, besides 2 and 3. It has been demonstrated that cluster 6 was formed from 2, while clusters 5 and 7 were formed from the further decomposition of 6. The reaction of 5 with SbPh3 afforded a monosubstituted derivative, Os6(μ4-Sb)(μ-H)2(μ-SbPh2)(μ3,η2-C6H4)(μ3,η4-C12H8)(CO)14(SbPh3), 8. The clusters 2−8 were all shown by single-crystal X-ray crystallographic studies to have a benzyne moiety acting as a four-electron donor to a triosmium fragment. In addition, 4 and 8 contain a novel μ3,η4-biphenylene moiety bound to a triosmium framework, while 7 was found to have a μ3,η1:η1:η6-C6H4 ring.