Diphosphine- and CO-induced fragmentation of chloride-bridged dinuclear complex and Cp^*Ir(μ-Cl)₃Re(CO)₃ and Attempted Synthesis of Cp^*Ir(μ-Cl)₃Mn(CO) ₃

The confacial bioctahedral compound Cp*Ir(μ-Cl) ₃Re(CO)₃ (1) undergoes rapid fragmentation in the presence of the unsaturated diphosphine ligand (Z)-Ph₂PCH = CHPPh₂ to give the mononuclear compounds [Cp^*IrCl{(Z)-Ph ₂PCH = CHPPh₂}][Cl] (2) and fac-ClRe(CO) ₃[(Z)-Ph₂PCH = CHPPh₂] (3). 2 has been characterized by ¹H and ³¹P NMR spectroscopy and X-ray diffraction analysis. 2•2CHCl₃ crystallizes in the monoclinic space group C2/c, a = 35.023 (8) å, b = 10.189 (2) å, c = 24.003 (6) å, β = 103.340 (3), V = 8,335 (3) å³, Z = 8, and d _calc = 1.647 Mg/m³; R = 0.0383, R _w = 0.1135 for 8,178 reflections with I > 2σ(I). The Ir(III) center in 2 exhibits a six-coordinate geometry and displays a chelating diphosphine group. Compound 1 reacts with added CO with fragmentation to yield the known compounds Cp ^*Ir(CO)Cl₂ (4) and ClRe(CO)₅ (5) in near quantitative yield by IR spectroscopy. Using the protocol established by our groups for the synthesis of 1, we have explored the reaction of [Cp ^*IrCl₂]₂ with ClMn(CO)₅ as a potential route to Cp^*Ir(μ-Cl)₃Mn(CO) ₃; unfortunately, 4 was the only product isolated from this reaction. The solid-state structure of 4 was determined by X-ray diffraction analysis. 4 crystallizes in the triclinic space group P-1, a = 7.4059 (4) å, b = 7.8940 (4) å, c = 11.8488 (7) å, α = 80.020 (1), β = 79.758 (1), γ = 68.631 (1), V = 630.34 (6) å³, Z = 2, and d _calc = 2.246 Mg/m³; R = 0.0126, R _w = 0.0329 for 2,754 reflections with I > 2σ(I). The expected three-legged piano-stool geometry in 4 has been crystallographically confirmed.