Chemical shift correlations in the 13C, 17O and 31P NMR spectra of some Mo(CO) 4((PPh 2O) 2Y(R)R′) (Y(R) = P(O), Si(Me); R′ = alkyl, haloalkyl, aryl) and [Mo(CO) 4(PPh 2O) 2] 2Si complexes

Abstract

The syntheses and 13C, 17O, 29Si and 31P NMR spectra of a series of Mo(CO) 4((PPh 2O) 2Y(R)R′) (Y(R) = P(O), Si(Me); R′=alkyl, haloalkyl, aryl) and [Mo(CO) 4(PPh 2O) 2] 2Si complexes are given. The chemical shift ranges of the cis and trans carbonyl 13C and 17O, phenyl C(1) 13C and 31P resonances are relatively large and, with the exception of the cis carbonyl 17O chemical shifts, the correlations between the chemical shifts of the various resonances are excellent. These correlations are consistent with the model of metal carbonyl 13C and 17O chemical shifts proposed by Bodner and Todd. In addition they allow the model to be extended to include the diphenylphosphinite 31P chemical shifts in these complexes. The excellent correlations may be due to the presence of the chelate ring which limits the rotation around the molybdenum-phosphorus bond and to the fact that all three groups directly bonded to the phosphorus remains constant.