Oxidative Addition of Water to Ir(I) Complexes Bearing a Pincer-Type Silyl Ligand

Abstract

Reaction of water with in situ generated [(PSiP-R)Ir I ] (PSiP-R = [{2-(R 2 P)C 6 H 4 } 2 MeSi] − ; R = cyclohexyl, t Bu or i Pr) from [(PSiP-R)Ir(H) 4 ] and tert -butylethylene (tbe) showed high ligand dependency. Oxidative addition of water cleanly proceeded in the reaction of [(PSiP- t Bu)Ir I ] in THF at room temperature to selectively afford a 16-electron hydrido–hydroxo complex [(PSiP- t Bu)Ir(H)(OH)] almost quantitatively. In contrast, the reaction of cyclohexyl and i Pr derivatives was unselective and formed various products containing Ir–H bonds. In the case of i Pr-derivative, a small amount of 18-electron hydrido–hydroxo aqua complex [(PSiP- i Pr)Ir(H)(OH)(H 2 O)] was isolated and structurally characterized by X-ray crystallography.

Two-Site O–H Addition to an Iridium Complex Featuring a Nonspectator Tricoordinate Phosphorus Ligand

“…Divergent reactivity is observed with S–H and Se–H bonds due in part to the disparate P–E (E = O, S, Se) bond enthalpies. Although the mechanism of O–H bond activation by complex 1 is the subject of ongoing research, we note that well-defined reactivity with Ir­(I) and O–H bonds is otherwise relatively uncommon. − Whereas tricoordinate phosphorus ligands have previously been proposed to assist in certain bond activations, the present results establish the first experimental demonstration of a metallophosphorane product resulting directly from intermolecular two-center oxidative addition . Accordingly, this new class of bifunctional metal–ligand cooperativity may facilitate other difficult bond activations, which will be the focus of future studies.…”