100700-67-2Relevant academic research and scientific papers
X-ray crystal structure and structural dynamics of [Ir3{μ-(Ph2PCH2)2AsPh} 2(μ-CO)2(CO)2(μ-Cl)Cl]+ and related rhodium complexes
Balch, Alan L.,Fossett, L. Alan,Guimerans, Rosalvina R.,Olmstead, Marilyn M.,Reedy Jr., Philip E.
, p. 1397 - 1404 (2008/10/08)
The preparation of the tetracarbonyl complexes [Ir3(μ-dpma)2(μ-CO)2(CO) 2(μ-X)X][BPh4], [Rh3(μ-dpma)2(μ-CO)2(CO) 2(μ-I)I][BPh4] and [Rh3(μ-dpmp)2(μ-CO)2(CO) 2(μ-X)X][BPh4] (dpma = bis((diphenylphosphino)methyl)phenylarsine; dpmp = bis((diphenylphosphino)methyl)phenylphosphine; X = Cl, Br, I) is reported. Infrared and electronic spectral data indicate that all have a common structure. [Ir3;{μ((C6H5)2PCH 2)2AsC6H5}2(μ-CO) 2(CO2)2(μ-Cl)Cl][B(C6H 5)4]·2CH2Cl2 crystallizes from dichloromethane/ether in the triclinic space group P1 (No. 2) with a = 12.789 (3) A?, b = 16.936 (4) A?, c = 23.874 (6) A?, α = 87.80 (2)°, β = 68.69 (2)°, γ = 77.05 (2)° at 140 K. Least-squares refinement of 493 parameters using 8413 reflections yields R = 0.083, Rw = 0.090. The structure of the cation has the two dpma ligands in a fully extended trans alignment. The three iridium atoms are nearly linear (Ir-Ir-Ir angle 166.0 (1)°) with Ir-Ir bonds of nearly equal lengths, 2.887 (1) and 2.842 (1) A?. One Ir-Ir bond is bridged by a chloride and a carbonyl ligand in a double-A-frame arrangement while the other Ir-Ir bond is bridged by a carbonyl ligand. A nearly statistical disorder in the crystal packing exchanges the sites of the bridging chlorine and the terminal chlorine. Multinuclear (31P, 1H, and 13C) NMR spectra of these tetracarbonyls in dichloromethane solution indicate that they have a time-averaged, symmetrical structure that renders the two end P2Ir environments equivalent. A dynamic process involving bridge/terminal halide interchange is proposed to explain these spectra.
