Phosphorus-31 NMR study of phosphine monosubstituted group VIB metal carbonyls

Abstract

The 31P chemical shift and coupling constants are reported for a series of carbonyl compounds of the type LM(CO) 5, with M = Cr, Mo, W, and L = a tertiary phosphine: (CH 3) 3P, (C 2H 5) 3P, (C 6H 5) 3P, (3-XC 6H 4) 3P (with X = F, Cl) and (4-XC 6H 4) 3P (with X = F, Cl, CH 3). For the chromium carbonyls the PCl 3, C 6H 5PCl 2 and (C 6H 5) 2PCl derivatives have also been studied. The theory of Ionin was used to explain the chemical shift. Where possible, the coordination chemical shift was interpreted in terms of σ and π bonding between P and M. These parameters were discussed by comparison with the corresponding phosphine—BCl 3 adducts. J PW is shown to be mainly dependent on inductive effects and J PH and J PF to change upon complexation of the free phosphine, according to the rule of Bent.