Aryldiazenido Complexes: Syntheses of Iridium Complexes with Doubly-Bent Aryldiazenido Ligands and X-ray Structure of [Cp(*)Ir(PMe3)2(p-N2C6H4OMe)][BF4]

Article abstract of DOI:10.1021/ic00128a030

[Cp(*)Ir(C2H4)(N2Ar)][BF4] (1; Ar =p-C6H4OMe) reacts with PMe3 to give [Cp(*)Ir(PMe3)2(N2Ar)][BF4] (4), which has been shown by an X-ray structure determination and by (15)N NMR spectroscopy to possess the aryldiazenido ligand bound with doubly-bent geometry. As is the case in 1, the complexes [Cp(*)Ir(PPh3)(N2Ar)][BF4] (2) and [Cp(*)Ir{P(p-tol)3}(N2Ar)][BF4] (3) have the N2Ar ligand bound with singly-bent geometry. This has been demonstrated by an X-ray structure determination for 3. Complexes 2 and 3 react with PMe3 to give [Cp(*)Ir(PPh3)(PMe3)(N2Ar)][BF4] (5) and [Cp(*)Ir{P(p-tol)3}(PMe3)(N2Ar)][BF4] (6), and 2 reacts with CO or CN(1-) to give [Cp(*)Ir(CO)(PPh3)(N2Ar)][BF4] (7) or Cp(*)Ir(CN)(PPh3)(N2Ar) (8). All these reactions are shown by (15)N NMR to involve the transformation of the N2Ar ligand from singly-bent to doubly-bent as a consequence of coordination by the incoming ligand. Diphos (Ph2P(CH2)2PPh2) reacts with 1 to give [Cp(*)Ir(diphos)(N2Ar)][BF4] (9), but no complex of stoichiometry [Cp(*)Ir(PPh3)2(N2Ar)][BF4] could be obtained from 1 or 2 with excess PPh3; this complex is presumably sterically disfavored. Crystal structures: 3, T = 295 K, orthorhombic, space group P212121, Z = 4; a = 12.974(2) ?; b = 13.449(2) ?, c = 16.213(4) ?, V = 2829.0 ?**3, RF = 0.032 for 2974 data (Io >= 2.5σ(Io)) and 241 variables;4, T = 295 K, monoclinic space group P21/n, Z = 4; a = 9.906(2) ?, b = 12.084(3) ?, c = 30.545(6) ?, β = 93.296(13)°, V= 3650.2 ?**3, RF = 0.029 for 3606 data (Io >= 2.5σ(Io)) and 422 variables.