Synthesis and reactivity of hydrazine complexes of iridium(III)

Hydride complexes IrHCl2[PPh(OEt)(2)]L-2 1, 3 and IrHCl2[P(OEt)(3)]L-2 2, 4 (L = PPh3 or AsPh3) were prepared by substituting one phosphine or arsine ligand in IrHCl2L3 with the appropriate phosphite. Treatment of hydrides 1-4 first with triflic acid (CF3SO3H) and then with hydrazines gave [IrCl2(RNHNH2){PPh(OEt)(2)}L-2]BPh4 5, 7 and [IrCl2(RNHNH2){P(OEt)(3)}L-2]BPh4 6, 8 (R = H, Me, Ph or C6H4NO2-4). Hydride-hydrazine complexes [IrH2(RNHNH2)(PPh3)(3)]BPh4 9 and [IrHCl(RNHNH2)(PPh3)(2)]BPh4 10 (R = H, Me or Ph) were also prepared by allowing IrH3(PPh3)(3) or IrH2Cl(PPh3)(3) to react sequentially first with CF3SO3H or HBF4. Et2O and then with the appropriate hydrazine. All complexes were fully characterised by IR and NMR spectroscopy and their geometry in solution was also established. Oxidation with Pb(OAc)(4) at -30 degrees C of arylhydrazines [IrCl2(ArNHNH2)L'L-2]BPh4 5-8 [L' = PPh(OEt)(2) or P(OEt)(3); Ar = Ph] afforded stable aryldiazene derivatives [IrCl2(ArN=NH){PPh(OEt)(2)}L-2]BPh4 11, 13 and [IrCl2(ArN=NH){P(OEt)(3)}L-2]BPh4 12, 14. By contrast, treatment with Pb(OAc)(4) at -30 degrees C of methylhydrazine complexes [IrCl2(MeNHNH2)L'L-2]BPh4 gave hydrides IrHCl2L'L-2. Aryldiazene complexes [IrCl2(ArN=NH)L'L-2]BPh4 11-14 and [{IrCl2L'L-2}(2)(mu-HN=NAr-ArN=NH)](BPh4)(2) 15-18 [Ar = Ph or C6H4Me-4; Ar-Ar = 4,4'-C6H4-C6H4 or 4,4'-(2-Me)C6H3-C6H3(Me-2)] were also prepared by allowing hydride species IrHCl2L'L-2 1-4 to react with the appropriate aryldiazonium cations in acetone at -80 degrees C. Their characterisation by IR and NMR spectroscopy (with N-15 isotopic substitution) is discussed.