ARYLDIAZENIDO COMPLEXES - SYNTHESES OF IRIDIUM COMPLEXES WITH DOUBLY-BENT ARYLDIAZENIDO LIGANDS AND X-RAY STRUCTURE OF CP-ASTERISK-IR(PME(3))(2)(P-N(2)C(6)H(4)OME)][BF4]

[CPIr(C2H4)(N2Ar)][BF4] (1; Ar = p-C(6)H(4)OMe) reacts with PMe(3) to give [CpIr(PMe(3))(2)(N2Ar)][BF4] (4), which has been shown by an X- ray structure determination and by N-15 NMR spectroscopy to possess th e aryldiazenido ligand bound with doubly-bent geometry. As is the case in 1, the complexes [CpIr(PPh(3))(N2Ar)][BF4] (2) and [Cp*Ir{P(p-tol )(3)}(N2Ar)][BF4] (3) have the N2Ar ligand bound with singly-bent geom etry. This has been demonstrated by an X-ray structure determination f or 3. Complexes 2 and 3 react with PMe(3) to give [CpIr(PPh(3))(PMe(3 ))(N2Ar)][BF4] (5) and [CpIr{P(p-tol)(3)}(PMe(3))(N2Ar)][BF4] (6), an d 2 reacts with CO or CN- to give [CpIr(CO)(PPh(3))(N2Ar)][BF4] (7) o r CpIr(CN)(PPh(3))(N2Ar) (8). All these reactions are shown by N-15 N MR to involve the transformation of the N2Ar ligand from singly-bent t o doubly-bent as a consequence of coordination by the incoming ligand. Diphos (Ph(2)P(CH2)(2)PPh(2)) reacts with 1 to give [CpIr(diphos)(N2 Ar)][BF4] (9), but no complex of stoichiometry [CpIr(PPh(3))(2)(N2Ar) ][BF4] could be obtained from 1 or 2 with excess PPh(3); this complex is presumably sterically disfavored. Crystal structures: 3, T = 295 K, orthorhombic, space group P2(1)2(1)2(1), 2 = 4; a = 12.974(2) Angstro m; b = 13.449(2) Angstrom, c = 16.213(4) Angstrom, V = 2829.0 Angstrom (3), R(F) = 0.032 for 2974 data (I-0 greater than or equal to 2.5 sigm a (I-0)) and 241 variables; 4, T = 295 K, monoclinic, space group P2(1 )/n, Z = 4; a = 9.906(2) Angstrom, b = 12.084(3) Angstrom, c = 30.545( 6) Angstrom, beta = 93.296(13)degrees, V = 3650.2 Angstrom(3), R(F) = 0.029 for 3606 data (I-0 greater than or equal to 2.5 sigma (I-0)) and 422 variables.