Di-rhodium(I) and tri-rhodium(I) complexes with bridging bis(dimethylphosphinomethyl) methylphosphine

Abstract

The reaction between bis(dimethylphosphinomethyl)methylphosphine (dmmm) and rhodium dicarbonyl chloride dimer can be controlled by the order of addition to give the purple [Rh 3(μ-dmmm) 2(CO) 3(μ-Cl)Cl][BPh 4] or the yellow [Rh 2(μ-dmmm) 2(CO) 2][BPh 4] 2. [Rh 3(μ-dmmm) 2(CO) 3(μ-Cl)Cl][B(C 6H 5) 4] · 2CH 2Cl 2 crystallizes in the triclinic space group P 1 (No. 2) with a 9.688(2), b 13.571(2), c 21.303(3) Å, α 80.18(1), β 84.74(1), γ 83.99(1)°, Z = 2 at 130 K. Least-squares refinement of 424 parameters using 8164 reflections with I > 3σ(I) yielded R = 0.044. The cation contains a bent (140.9(1)°) tri-rhodium chain with each rhodium having planar P 2(CO)Cl coordination. Treatment of [Rh 2(μ-dmmm) 2(CO) 2][BPh 4] 2 with diiodomethane or sodium iodide yields [Rh 2(μ-dmmm) 2(CO)I][BPh 4]. Yellow crystals of [Rh 2(μ-dmmm) 2(CO)I][B(C 6H 5) 4] · (CH 3) 2CO crystallize in the orthorhombic space group P2 12 12 1 (No. 19) with a 9.760(3), b 14.931(4), c 32.708(8) Å, Z = 4 at 130 K. Least-squares refinement of 386 parameters using 4244 reflections yield R = 0.044. The structure of the cation consists of a four-coordinate, planar rhodium (with bonds to the other rhodium, two PMe groups and the terminal carbonyl group) and a six-coordinate rhodium (with bonds to the four PMe 2 groups, the terminal iodide, and the other rhodium, at 2.735(1) Å).