A PHOSPHORUS-TIN CAGE MOLECULE WITH AN EXTREMELY SHIELDED P-31 NUCLEUS - P-4[SN(C6H5)(2)](3)

The structure of the compound P-4[Sn(C6H5)(2)](3) was deduced from the Sn-119 and P-31 NMR spectra and it was shown to be a structural analo gue of the hetero-nortricyclene P4S3. The apical phosphorus atom exhib its an extremely negative P-31 chemical shift of -554.65 ppm, and the basal phosphorus atoms also resonate at high field strengths. The P-31 spectrum includes all tin satellite signals of the [mono-Sn-117/119] isotopomers. The spectra are analyzed as A(2)A'MX spin systems (A, M = P-31; X = Sn-117/119). The P-31 data for analogous tricyclic cage mol ecules are presented and discussed. (C) 1998 John Wiley & Sons, Ltd.