- Synthesis, molecular structure and reactivity of neutral and cationic dinuclear iridium complexes with bridging azavinylidene ligands
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The mononuclear iminoiridium complexes [IrCl{κ 1-NH=C(Ph)R}(η4-C8H12)] (2-4) are obtained from [Ir(μ-Cl)(η4-C8H 12)]2 and HN=C(Ph)R (R = Ph, Et, H) by cleavage of the chloro bridges. The reaction of 2 (R = Ph) with NaN(SiMe3) 2 affords the dinuclear complex [Ir(μ-N=CPh2)(η 4-C8H12)]2 (5), which reacts with the haloforms HCX3 (X = Cl, Br, I) via oxidative addition of X 2 to give the IrII-IrII compounds [IrX(μ-N=CPh2)(η4-C8H 12)]2 (6-8). The X-ray crystal structure analysis of 6 (X = Cl) reveals the presence of a metal-metal bond in this molecule. The reaction of 5 with CH3Br and CH3I yields the neutral complexes [(η4-C8H12)Ir(CH3)(μ -N=CPh2)2Ir(X)(η4-C8H 12)] (9, 10), which in chloroform solution generate the ionic compounds [(η4-C8H12)Ir(CH 3)(μ-N=CPh2)2Ir(η4-C 8H12)]X (12, 13) by dissociation of the Ir-X bonds. The corresponding complex 11 with CF3SO3- as the anion is formed from 5 and CF3SO3CH3. Treatment of 11 and 13 with tBuNC leads to the formation of the compounds [(η4-C8H12)Ir(CH3)(μ -N=CPh2)2Ir(CNtBu)(η4-C8H 12)]X (14, 15). While the reactions of 5 with CF3SO 3H, HBF4, [Au(PPh3)][BF4] and [NO][PF6] afford the unsymmetrical dinuclear complexes 17-20 via Addition von H+, [Au(PPh3)]+ and NO+ at one of the metal centres, treatment of 5 with CF3CO2H yields the mononuclear imino compound [(η4-C8H 12)Ir{κ1-OC(O)CF3}(κ 1-NH=CPh2)] (16) by cleavage of the bridging azavinylidene-metal bonds.
- Werner,Müller,Steinert
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