PRODUCTS FROM THE PHOTOREACTION OF (ME3P)(OC)(4)OSW(CO)(5) WITH CCL4 - SYNTHESIS AND ISOMERIZATION OF OS(CO)(3)(PME3)CL-2

This paper reports the characterization of the fac-Os(CO)(3)(PMe3)Cl-2 (fac-2) product that is formed when (Me3P)(OC)(4)OsW(CO)(5) (1; a com plex with a dative Os-W bond) is irradiated (lambda > 400 nm) in the p resence of CCl4. In an attempt to independently synthesize fac-2, Os-3 (CO)(9)(PMe3)(3) was allowed to react with Cl-2. The product, however, was mer-cis-Os(CO)(3)(PMe3)Cl-2 (mer-cis-2). The mer-cis isomer is co nverted to the fac isomer (fac-2) by stirring under nitrogen in THF fo r nine days. The stereochemistry of each compound was confirmed by inf rared and NMR spectroscopy and by X-ray crystallography. The [Os(CO)(2 )(PMe3)(Cl)(mu-Cl)](2), compound (3) was also formed as a minor produc t in the conversion of mer-cis-Os(CO)(3)(PMe3)Cl-2 to fac-Os(CO)(3)(PM e3)Cl-2. Irradiation (lambda > 400 nm) of Os(CO)(4)(PMe3) in benzene i n the presence of CCl4 gave a product tentatively identified as fac-Os (CO)(3)(PMe3)(CCl3)Cl (4),which results from the oxidative-addition of CCl4 to Os(CO)(3)(PMe3). (C) 1997 Elsevier Science S.A.