Synthesis and some reactivity of cationic alkyl nitrosyl iridium(III) derivatives

The iridium(III) dimethyl derivatives [Ir(Me)(2)Cp*(L)] (Cp* = eta(5)-C5Me5 ; L = PPh3 (1a), PMePh2 (1b), PMe2Ph (1c), PMe3 (1d)) react with NOBF4 in C H2Cl2 to give the iridium(III) cationic alkylnitrosyl derivatives [Ir(Me)(2 )Cp*(NO)]BF4 (2), and [Ir(Me)Cp*(NO)(L)](BF4)(2) (L = PMePh2 4b, PMe2Ph 4c, PMe3 4d). EPR spectroscopy shows that the reaction proceeds through the ir idium(IV) intermediates 1a(+)-1d(+). Treatment of 1d with NOBF4 in acetonit rile gives, in addition to 4d, the acetonitrile substitution products [Ir(M e)Cp*(CH3CN)(PMe3)]BF4 (5d) and [IrCp*(CH3CN)(2)(PMe3)](BF4)(2) (6d). Elect rochemical and chemical reduction of 4b-4d afford the corresponding [Ir(Me) Cp*(NO)(L)](BF4) 7b-7d, which have been studied by EPR spectroscopy. Reacti on of 2 with PPh3 gives [Ir(Me)(2)Cp*(PPh3)]; treatment of 4b and 4c with t he appropriate phosphine gives [Ir(Me)Cp*(L)(2)](BF4) (L = PMePh2, PMe2Ph), respectively. (C) 1999 Elsevier Science S.A. All rights reserved.