Two phenyl rings of triphenylphosphanehave been modified by electron-withdrawing trifluoromethyl groups. A methoxy group has been introduced at the para-position of the third ring. Due to the activating effect of the methoxy group, the phosphane can be monosulfonated under mild conditions and with complete selectivity. The novel ligand, sodium 5-[bis-(4-trifluoromethylphenyl)phosphanyl]-2-methoxybenzenesulfonate