Abstract

The reaction of 1,2,3-triphenylphosphirene with [H2Os3-(CO)10] leads to the title compound, [Os3(CO)9{(C6H5)3-C 2PO}], which displays an open Os3(CO)9 cluster [Os-Os 2.703 (1) and 2.867 (2) Å, and Os-Os-Os 124.24 (4)°]. This moiety is ?3,?3-bonded to a phosphirene ligand with a cleaved P-C bond, PhC-C(Ph)-P. An O atom was incorporated into the molecule resulting in an unusual five-membered metallacycle, Os-C-C-P-O, with distances Os-C 2.10 (1), C-C 1.46 (2), C-P 1.76 (1), P-O 1.628 (9) and O-Os 2.136 (9) Å. This ring makes a dihedral angle of 57.3 (2)° with the plane of the metal atoms.