Oxidative Addition of X−H (X = C, N, O) Bonds to [Ir(PMe3)4]Cl and Catalytic Hydration of Acetonitrile Using its Peroxo Derivative, [Ir(O2)(PMe3)4]Cl, as Catalyst Precursor.

The reactions of [Ir(PMe3)4]Cl (1) with a variety of substrates (acetonitrile, p-aminobenzonitrile, p-cyanophenol) containing a nitrile group were examined. Cleavage of the X−H bonds occurred selectively over the coordination of the CN moiety in those substrates, and compounds derived from the corresponding X−H (X = C, N, O) oxidative addition reaction, namely, cis-[IrH(CH2CN)(PMe3)4]Cl (2), cis-[IrD(CD2CN)(PMe3)4]Cl (3), cis-[IrH(p-NHC6H4CN)(PMe3)4]Cl (4), and cis-[IrH(p-OC6H4CN)(PMe3)4]Cl (6), were obtained. X-ray diffraction studies have confirmed the structures of 3and 4. In the case of 6, the compound trans-[IrClH(PMe3)4][p-OC6H4CN] (5b), resulting from exchange of Cl and p-OC6H4CN anions between inner and outer sphere, was also formed, and the solid-state structure (5b·HOC6H4CN), obtained by X-ray diffraction, contained the hydrogen-bonded NCC6H4O···H···OC6H4CN anion. The salt [Ir(PMe3)4][BPh4] (7) was also prepared, characterized by X-ray diffraction and reacted with p-HOC6H4CN. Reaction of 1with acetamide, the product of acetonitrile hydration, was undertaken to gain insight into the nitrile hydration process, and the single-crystal structure of the N−H bond cleavage product, cis-[IrH(NHC(O)Me)(PMe3)4]Cl (8), was determined by X-ray diffraction. The peroxo compound derived from reaction of 1with O2, [Ir(O2)(PMe3)4]Cl (9), was prepared, characterized by X-ray diffraction, and used as a catalyst precursor for the hydration of acetonitrile using the protio and deuterio mixtures of substrates, CH3CN/H2O (A), CD3CN/D2O (B), CD3CN/H2O (C), and CH3CN/D2O (D). Catalysis occurred cleanly at 140 °C, giving dn-acetamides; the formation of these was monitored by 1H and 13C{1H} NMR spectroscopy and GC/MS. In situ31P{1H} NMR spectroscopic studies during catalysis confirmed the formation of OPMe3. [ABSTRACT FROM AUTHOR]