Ligand chelation, P–C bond cleavage, and phenyl-group transfer in the reaction between RCCo 3(CO) 9 and 1,8-bis(diphenylphosphino)naphthalene (dppn): Syntheses and X-ray diffraction structures of PhCCo 3(CO) 4(μ-CO) 3(dppn) and PhCCo 3(CO) 8[η 1-PPh(OH)C 10H 6P(O)Ph 2

Abstract

The tricobalt cluster PhCCo 3(CO) 9 ( 1) undergoes facile ligand substitution with 1,8-bis(diphenylphosphino)naphthalene (dppn) under thermal and Me 3NO activation to afford the cluster compounds PhCCo 3(CO) 8[PPh 2(1-C 10H 7)] ( 2) and PhCCo 3(CO) 4(μ-CO) 3(dppn) ( 3). Whereas thermolysis of dppn with the methylidyne-capped cluster HCCo 3(CO) 9 ( 4) yields only HCCo 3(CO) 8[PPh 2(1-C 10H 7)] ( 5) and HCCo 3(CO) 4(μ-CO) 3(dppn) (6) as isolable products, the reaction between 4 and dppn in the presence of Me 3NO furnishes the latter two clusters in addition to the phenyl-capped cluster PhCCo 3(CO) 8[η 1-PPh(OH)C 10H 6P(O)Ph 2] ( 7). The clusters 2 and 5 represent simple substitution products based on the ligand diphenyl(1-naphthyl)phosphine, while clusters 3 and 6 each possess a chelating dppn ligand and three bridging CO groups in the solid state. Oxidation of the two phosphine moieties by Me 3NO and transfer of one of the phenyl groups from the dppn ligand to the methylidyne carbon moiety in cluster 4 produces the thermally unstable cluster 7. These clusters have been characterized in solution by IR and 31P NMR spectroscopies, and the solid-state structures of 3 and 7 established by X-ray crystallography.