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(RN HNH2){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)(PPh 3)(3)]BPh4 9 and [IrHCl(RNHNH2)(PPh3)(2)]BPh4 10 (R = H, Me or Ph) were als o prepared by allowing IrH3(PPh3)(3) or IrH2Cl(PPh3)(3) to react sequential ly first with CF3SO3H or HBF4. Et2O and then with the appropriate hydrazine . All complexes were fully characterised by IR and NMR spectroscopy and the ir 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 1 2, 14. By contrast, treatment with Pb(OAc)(4) at -30 degrees C of methylhyd razine complexes [IrCl2(MeNHNH2)L'L-2]BPh4 gave hydrides IrHCl2L'L-2. Aryld iazene 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 ace tone at -80 degrees C. Their characterisation by IR and NMR spectroscopy (w ith N-15 isotopic substitution) is discussed.