15008-65-8Relevant academic research and scientific papers
FORMATION OF DIARYLS BY THERMAL DECOMPOSITION OF RHODIUM(I) TRIARYLPHOSPHINE COMPLEXES
Lewin, Maxine,Aizenshtat, Zeev,Blum, Jochanan
, p. 255 - 261 (1980)
Chlorotris(triphenylphosphine)rhodium, RhCl(PPh3)3 undergoes thermal decomposition above 140 deg C in solution and in the solid state to yield biphenyl.Rhodium complexes with para-substituted triphenylphosphine ligands form exclusively 4,4'-disubstituted biphenyls.Mixtures of two complexes RhCl(PAr3)3 and RhCl(PAr'3)3 form the crossed diaryl ArAr' and two non-crossed compounds (Ar)2 and (Ar')2.The mechanism is assumed to involve dissociation of RhCl(PPh3)3 into PPh3 and solvated RhCl(PPh3)2 followed by oxidative addition of the liberated phosphine to the latter bis-triphenylphosphine compound.Evidence for a phenyl-rhodium intermediate has been provided by phenylation of styrene by RhCl(PPh3)3.In an independent process, RhCl(PPh3)3 forms benzene by an ortho-metallation route.
Synthesis, structure, and ligand-promoted reductive elimination in an acylrhodium ethyl complex
Suggs, J. William,Wovkulich, Michael J.,Cox, Sherman D.
, p. 1101 - 1107 (2008/10/08)
8-Quinolinecarboxaldehyde and [(C2H4)2RhCl]2 reacted to give a polymeric acylrhodium ethyl compound which was solubilized by pyridine to give chloroethyl(8-quinolinecarbonyl-C,N)(pyridine)rhodium. This compound was stable in the presence of amine ligands, but phosphine ligands caused rapid reductive elimination. Intermediates in the reductive elimination were observed at -40°C by using 1H, 13C, and 31P NMR in the case of the ligand PPh3. In the first-formed intermediate PPh3 displaced pyridine. The resulting five-coordinated Rh(III) complex reductively eliminated (with an observed first-order rate constant of 3.7 × 10-4 s-1 at -40°C) to give an η2-ketone Rh(I) intermediate. With excess phosphine RhCl(PPh3)3 and 8-quinolinyl ethyl ketone were the final products. Recrystallization of the starting pyridine complex from pyridine-ether gave Cl(C2H5)Rh(C10H6NO)(C 5H5N)2·1/2C 4H10O (chloroethyl(8-quinolinecarbonyl-C,N)bis(pyridine)rhodium-hemi(diethyl ether)), whose structure was determined by single-crystal X-ray diffraction. The compound crystallizes in the triclinic space group P1 with two molecules in the unit cell a = 8.933 (3) A?, b = 17.573 (8) A?, c = 7.760 (2) A?, α = 97.57 (3)°, β = 98.04 (2)°, and γ = 79.98 (3)°. The least-squares refinement with anisotropic thermal parameters for all non-hydrogen atoms converged at RF = 0.046 (RwF = 0.055) for 2595 observed reflections and 262 parameters refined.
