SYNTHESIS, CRYSTAL-STRUCTURE AND NUCLEAR-MAGNETIC-RESONANCE SPECTRAL STUDY OF THE (-(R,R,R-ASTERISK,S-ASTERISK)- AND (-)-(S,S,R-ASTERISK,S-ASTERISK)-ENANTIOMERS OF THE CHIRAL DIPHOSPHINE[C6H4(PPHCH(2)CHO)(2)CME(2)]-1,2())

Treatment of the dilithiodiphosphide [Li(tmen)](2)[C6H4(PPh)(2)-1,2] ( tmen = N,N,N',N '-tetramethylethylenediamine) with (-)-(R,R)- or (+)-( S,S)-Me(2)C(OCHCH(2)OSO(2)C(6)H(4)Me-p)(2) afforded the enantiomeric c hiral diphosphine (+)-(R,R,R,S*)- or (-)-(S,S,R*,S*)- [C6H4(PPhCH(2)C HO)(2)CMe(2)]-1,2, respectively. Their crystal Structures have been de termined which show them to be isostructural; hence they are enantiome rs rather than diastereoisomers. Thus the original chirality of Me(2)C (OCHCH(2)OSO(2)C(6)H(4)Me-p)(2) induces a preferred chirality at the P atoms of the product diphosphines. A H-1 and P-31 NMR spectral study of (+)-(R,R,R,S*)-[C6H4(PPhCH(2)CHO)(2)CMe(2)]-1.2 has been carried o ut; involving selective decoupling and nuclear Overhauser experiments, Karplus curves for both (3)J(HH) and (2)J(PH) couplings and ring curr ent shielding effects. This allows assignments to be made of the P-31 and non-aromatic H-1 signals. and demonstrates that the structure dete rmined by X-ray crystallography in the solid state is not significantl y changed in solution.