Mixed-metal cluster chemistry, VIII:: phosphite substitution at [CpWIr3(CO)11];: X-ray crystal structure of [CpWIr3(μ-CO)3(CO)6{P(OPh)3}2]

Reactions of [CpWIr3(CO)(11)] (1) with stoichiometric amounts of phosphites 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 and 7 are fluxional in solution, with the interconverting isomers resolvable at low temperatures. A structural study of 6 reveals that the three edges of a WIr2 face of the tetrahedral core are spanned by bridging carbonyls, and that iridium-bound triphenylphosphites ligate radially and axially and the tungsten-bound cyclopentadienyl coordinates axially with respect to this WIr2 face. Information from this crystal structure, P-31-NMR data, and results with analogous triphenylphosphine-ligated tungsten-triiridium clusters have been employed to suggest coordination geometries for the isomers. (C) 1998 Elsevier Science S.A. All rights reserved.