Half-sandwich hydrazine complexes of iridium: Preparation and reactivity

Chloro complexes IrCl2(η5-C5Me5)[P(OR)3] (1) (RMe, Et) were prepared by reacting dimer [IrCl2(η5-C5Me5)]2 with phosphites in alcohol. Treatment of 1 with R1NHNH2 gave monohydrazine complexes [IrCl(η5-C5Me5)(R1NHNH2)(P(OR)3)]BPh4 (2, 3, 4) [R1H (2), Me (3), Ph (4)]. Bis(hydrazine) complexes [Ir(η5-C5Me5)(R1NHNH2)2(P(OR)3)](BPh4)2 (5, 6) were prepared by reacting chloro complexes first with AgOTf and then with an excess of hydrazine. Oxidation with Pb(OAc)4 at -40°C of both mono- and bis(hydrazine) complexes afforded phenyldiazene derivatives [IrCl(η5-C5Me5)(PhNNH)(P(OR)3)]BPh4 (7) and [Ir(η5-C5Me5)(PhNNH)2(P(OR)3)](BPh4)2 (9). Bis(aryldiazene) [Ir(η5-C5Me5)(PhNNH)2(P(OR)3)](BPh4)2 (9, 10) were also prepared by allowing hydride IrH2(η5-C5Me5)[P(OR)3] (8) to react with aryldiazonium cations [ArN2]BF4. The complexes were characterised spectroscopically and by X-ray crystal structure determination of [IrCl(η5-C5Me5)(NH2NH2)(P(OEt)3)]BPh4 (2b) and [IrCl(η5-C5Me5)(CH3NHNH2)(P(OEt)3)]BPh4 (3b).