名称:
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
摘要:
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 3 and 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 center dot HOC6H4CN), obtained by X-ray diffraction, contained the hydrogen-bonded NCC6H4O center dot center dot center dot H center dot center dot center dot OC6H4CN anion. The salt [Ir(PMe3)(4)][BPh4] (7) was also prepared, characterized by X-ray diffraction and reacted with p-HOC6H4CN. Reaction of 1 with acetamide, the product of acetonitrile hydration, was under-taken 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 1 with O-2, [Ir(O-2)(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 degrees C, giving d(n)-acetamides; the formation of these was monitored by H-1 and C-13{H-1} NMR spectroscopy and GC/MS. In situ P-31{H-1} NMR spectroscopic studies during catalysis confirmed the formation of O=PMe3.