Iridium isocyanide complexes containing bis(diphenylphosphino)methane. The crystal and molecular structures of [IrH(CNC(CH 3) 3) 3((C 6H 5) 2PCH 2P(C 6H 5) 2)](PH 6) 2 · 2HC(O)N(CH 3) 2, [Ir 2(CNC(CH 3) 3) 4(μ-CO)(μ-CH 3O 2CCCCO 2CH 3)((C 6H 5) 2PCH 2P(C 6H 5) 2) 2] (B(C 6H 5) 4) 2·2HC(O)N(CH 3) 2 and [Ir 2(CNC(CH 3) 3) 4(μ-CO)((C 6H 5)

Abstract

Reaction of [Ir(CNBu t) 4]Cl with bis(diphenylphosphino)methane (DPPM) and NH 4PF 6 in ethanol forms [IrH(CNBu t) 3(DPPM)](PF 6) 2 ( 1). The hydride ligand exhibits spin coupling to one methylene proton of the DPPM ligand. The complex originally formulated as [Ir 2(CNBu t) 4(μ-MeO 2CCCCO 2Me)(DPPM) 2](BPh 4) 2, prepared from [Ir 2(CO) 3Cl(μ-MeO 2CCCCO 2Me)(DPPM) 2]BPh 4, excess CNBu t and NaBPh 4, has been shown to be [Ir 2(CNBu t) 4(μ-CO)(μ-MeO 2CCCCO 2Me)(DPPM) 2](BPh 4) 2 ( 2) with a very long, non-bonding IrIr separation of 3.6274(6) Å. In [Ir 2(CNBu t) 4(μ-CO)(DPPM) 2](BPh 4) 2 ( 3), however, the IrIr distance is 2.8063(4) Å, indicating the presence of a metal-metal bond. Complex 1 is monoclinic, P2 1/ m,a = 12.048(2), b = 12.922(2), c = 18.548(3) Å, β = 90.41(2)°, Z = 2,5131 reflections [ I⩾3σ( I)], R = 0.036, R w = 0.05 1. Complex 2 is monoclinic, P2 1/ n, a = 20.712(4), b = 18.594(3), c = 33.623(6) Å, β = 106.02(3)°, Z = 4,8563 reflections [ I⩾3σ(I)], R = 0.046, R w = 0.074. Complex 3 is triclinic, P1̄, a = 15.407(2), b = 25.885(3), c = 14.057(5) Å, α = 97.31(2), β = 96.77(2), γ = 92.74(1)°, Z = 2,8374 reflections [ I⩾3σ( I)], R = 0.037, R w = 0.058. Variations in IrIr bond lengths in DPPM-bridged binuclear iridium complexes are discussed.