Modification of Wilkinson's catalyst with triphenyl phosphite: Synthesis, structure, 31P NMR and DFT study of trans-[RhCl(P(OPh) 3)(PPh3)2]

Article abstract of DOI:10.1016/j.poly.2012.06.086

The complex trans-[RhCl(P(OPh)₃)(PPh₃)₂] (1) has been prepared and characterized by ³¹P NMR spectroscopy and single crystal X-ray crystallography. It was found that in the solid state there are two forms of complex 1 in the unit cell forming a cocrystal. DFT theoretical computations have confirmed the existence of the two forms and have provided evidence for the greater stability of 1 compared with Wilkinson's catalyst, [RhCl(PPh₃)₃] (2), in terms of the dissociation energy of the Rh-P(PPh₃) bonds. On the basis of the phosphorus chemical shifts, δ P(PPh₃), and the results of the theoretical computations, it is suggested that the Rh-P(PPh₃) bonding interactions are slightly enhanced in 1 compared with 2. A distinct difference between complexes 1 and 2, was found to be the catalytic activity of 1 in the alkylation of allyl acetate with sodium diethylmalonate, while 2 is almost catalytically inefficient.