Substitution Reactions of a <i>μ</i>₃-<i>η</i>¹:<i>η</i>²:<i>η</i>¹-C₆₀ Triosmium Cluster Complex and Formation of a Novel <i>μ</i>₃-<i>η</i>¹:<i>η</i>¹:<i>η</i>²-C₆₀ Bonding Mode

Decarbonylation of Os3(CO)8(CNR)(μ3-CNR)(μ3-η1:η2:η1-C60) (1; R = CH2Ph) with Me3NO/MeCN and subsequent thermal reactions with various 2e-donor ligands afford the respective substitution products Os3(CO)7(CNR)(μ3-CNR)(L)(C60) (L = (μ-H)2 (2), CNR (3), PMe3 (4), PPh3 (5)) in high yields. Compounds 2−5 have been characterized by spectroscopic (MS, IR, and 1H, 13C, and 31P NMR) and microanalytical data. Compounds 3 and 4 consist of three isomeric forms due to a 3-fold rotation on the outer Os center with a terminal benzyl isocyanide ligand, whereas 2 and 5 exist as a single isomer. The molecular structures of 2−5 have been determined by X-ray single-crystal diffraction studies. The hydride ligands of 2 have not been directly located, but ligand arrangements around the inner Os atom of the open-chain Os3 framework suggest that the two hydride ligands bridge the two Os−Os edges, respectively. The added isocyanide ligand in 3 is coordinated to an equatorial site on the inner Os center. The PMe3 ligand in 4 is positioned at the axial site of the inner Os atom. The μ3-η1:η2:η1-C60 interactions between C60 and metal clusters are not significantly altered by substitution of the corresponding ligands in 2−4. The PPh3 ligand in 5, however, is bound at the less hindered equatorial site of the outer Os center and leads to an orbital reorganization of the C6 ring of C60 from μ3-η1:η2:η1-C60 (1) to μ3-η1:η1:η2-C60 (5).