Optically active asymmetric di(tertiary phosphines). Crystal and molecularstructure of [SP-4-3-(S-P,S)]-{1-[(2-chlorophenyl)methylphosphino]-2-(dimethylphosphino)benzene-P,P '}{1-[1-(dimethylamino)ethyl]naphthyl-C-2,N}palladium(II) hexafluorophosphate

Mono-deprotonation of the bis(secondary phosphine) (R-P*,R-P*)- and (R-P*,S -P*)-1,2-phenylenebis(methylphosphine) has been achieved using potassium in liquid ammonia to give a ca. 4 : 1 mixture of (+/-)-1-(dimethylphosphino)- 2-(methylphosphino)benzene and 1,2-phenylenebis(dimethylphosphine) upon add ition of a solution of methyl iodide in the same solvent. This mixture has been further treated with sodium in THF followed by the addition of 1,2-dic hlorobenzene to give (+/-)-(2-chlorophenyl)(2-dimethylphosphinophenyl)methy lphosphine and unchanged 1,2-phenylenebis(dimethylphosphine). The two di(te rtiary phosphines) are readily separated by fractional distillation. Asymme tric di(tertiary phosphine) (+/-)-(2-chlorophenyl)(2-dimethylphosphinopheny l)methylphosphine has been resolved by separation via fractional crystallis ation of internally diastereomeric palladium(II) complexes containing the r acemic ligand and orthometallated (S)-dimethyl[1-(1-naphthyl)ethyl]amine. T he absolute configuration of the R enantiomer of the ligand has been assign ed by a crystal structure determination of the least soluble diastereomeric palladium(II) complex [SP-4-3-(S-P,S)]{1-[(2-chlorophenyl)methylphosphino] -2-(dimethylphosphino)benzene-P,P'}{1-[1-(dimethylamino)ethyl]naphthyl-C-2, N}palladium(II) hexafluorophosphate.