Abstract
1,4-Bis(2,6-dimethylphenyl)-1,4-diaza-1,3-butadiene (dab) forms the structurally characterized iridium(III) complex [Cp*IrCl(dab)](PF6): C28H35ClF6IrN2P, orthorhombic, space group Pnma, a = 16.187(2) \AA, b = 15.823(2) \AA, c = 11.677(1) \AA, V = 2990.8(6) \AA3, Z = 4, and R = 0.0588. On reaction with NaBH3CN this compd. does not form an iridium(III) hydride but the coordinatively unsatd. reduced product Cp*Ir(dab): C28H35IrN2, monoclinic, space group P21/n, a = 8.484(2) \AA, b = 14.535(3) \AA, c = 20.956(4) \AA, b = 98.88(3)°, V = 2553.2(9) \AA3, Z = 4, and R = 0.0586. The inverted relation dCC (=1.334(15) \AA) \textless dCN (=1.379(13) and 1.366(14) \AA) in the dab ligand of Cp*Ir(dab) suggests that the redn. has occurred primarily at that ligand to form an ene-1,2-diamido/iridium(III) moiety or, alternatively, a six-p-electron metallaheteroarom. system. Ab initio pseudopotential calcns. of model complexes [CpIr(HNCHCHNH)]0/2+ support this description of the bonding. [on SciFinder(R)]
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