THE PREPARATION, CRYSTAL-STRUCTURE AND SOME REACTION CHEMISTRY OF -PENTAPHENYLCYCLOPENTADIENYL)DICARBONYLOSMIUM(II), [OS(ETA(5)-C5PH5)(CO)(2)BR]

The preparation and characterisation of [Os(eta(5)-C5Ph5)(CO)(2)Br] (1 ) are described;this complex is the first reported C5Ph5- derivative o f osmium. A single crystal X-ray diffraction study of (1); (refined to R = 0.040, R-w = 0.043) is also reported. The related complexes, [Os{ eta(5)-C5Ph4(p-(BuC6H4)-Bu-i)}(CO)(2)Br] (2) and [Os{eta(5)-C-5(p-MeC6 H4)(5)} (CO)(2)Br] (3), have also been prepared. Carbonyl substitution of (1) in tetrahydrofuran following treatment with Me3NO afforded [Os (eta(5)-C5Ph5)(CO)(L)Br] (L=PMe2Ph (4), P(OEt)(3), (5), P(OCH2)(3)CCH3 (6) and (BuNC)-Bu-i (7)). A single crystal X-ray diffraction study of (6) (refined to R = 0.066, R-w = 0.073) is described. (C) 1998 Elsevi er Science Ltd. All rights reserved.