Mixed-metal cluster chemistry XII: isocyanide derivatives of [CpWIr3(CO)11]; X-ray crystal structure of [CpWIr3(CO)9(CNC6H3Me2-2,6)2]

Abstract

Reactions of [CpWIr3(CO)11] (1) with stoichiometric amounts of isocyanides afford the clusters [CpWIr3(CO)11-n(CNR)n] [R = Xy (C6H3Me2-2,6), n = 1 (2), 2 (3), 3 (4); R = tBu, n = 1 (5), 2 (6), 3 (7)] in good to excellent yields (47-63%). The products exhibit ligand fluxionality in solution, with the 13C-NMR spectra of 4-6 revealing that the carbonyls are undergoing fast exchange at 143 K. A single-crystal X-ray study of [CpWIr3(CO)9(CNXy)2] (3) reveals that the coordination sphere of the cluster has an all-terminal ligand geometry, the first for a ligand substituted derivative of 1. The two iridium-ligated 2,6-dimethylphenylisocyanide ligands are coordinated to the same iridium vertex, the second example of this coordination geometry for a transition metal cluster.