Addition of primary phosphines to the unsaturated triosmium cluster [(μ-H)Os 3(CO) 8{Ph 2PCH 2P(Ph)C 6H 4}]: Synthesis of triosmium clusters bearing dppm, phosphide and phosphinidene ligands via P–H bond activation

Abstract

Treatment of the electronically unsaturated cluster [(μ-H)Os 3(CO) 8{Ph 2PCH 2P(Ph)C 6H 4}] ( 1) with primary phosphines PPhH 2 and PCyH 2 gives the phosphido bridged compounds [(μ-H)Os 3(CO) 8(μ-PPhH)(μ-dppm)] ( 2) and [(μ-H)Os 3(CO) 8(μ-PCyH)(μ-dppm)] ( 3), respectively, by P–H bond activation of the phosphines and demetallation of the phenyl ring of the diphosphine ligand. Thermolysis of 2 and 3 in refluxing octane at 128 °C results in the formation of the phosphinidene compounds [(μ-H) 2Os 3(CO) 7(μ 3-PPh)(μ-dppm)] ( 4) and [(μ-H) 2Os 3(CO) 7(μ 3-PCy)(μ-dppm)] ( 5), respectively, by further P–H bond cleavage of the phosphido groups. All the compounds have been characterized by infrared, 1H NMR, 31P{ 1H} NMR and mass spectroscopic data together with single-crystal X-ray diffraction studies for 4. Compound 4 consists of a triangular cluster of osmium atoms with a symmetrically capped phosphinidene ligand and a bridging dppm ligand.