MIXED-METAL CLUSTER CHEMISTRY, VIII - PHOSPHITE SUBSTITUTION AT [CPWIR3(CO)(11)] - X-RAY CRYSTAL-STRUCTURE OF [CPWIR3(MU-CO)(3)(CO)(6)(P(OPH)(3))(2)]

Reactions of [CpWIr3(CO)(11)] (1) with stoichiometric amounts of phosp hites afford the substitution products [CpWIr3(mu-CO)(3)(CO)(8-n)(L)(n )] [L = P(OMe)(3), n = 1 (2), 2 (3), 3 (4); L = P(OPh)(3); n = 1 (5), 2 (6), 3 (7)] in fair to excellent yields (29-71%). Clusters 2, 4, 5 a nd 7 are fluxional in solution, with the interconverting isomers resol vable at low temperatures. A structural study of 6 reveals that the th ree edges of a WIr2 face of the tetrahedral core are spanned by bridgi ng carbonyls, and that iridium-bound triphenylphosphites ligate radial ly and axially and the tungsten-bound cyclopentadienyl coordinates axi ally with respect to this WIr2 face. Information from this crystal str ucture, P-31-NMR data, and results with analogous triphenylphosphine-l igated tungsten-triiridium clusters have been employed to suggest coor dination geometries for the isomers. (C) 1998 Elsevier Science S.A. Al l rights reserved.