SYNTHESIS, STRUCTURE AND REACTIONS OF SOME ORGANYL-BIS[N-(N',N',N'', N''-TETRAMETHYL)GUANIDINYL]PHOSPHINES AND DIORGANO-[N-(N',N',N'',N''-TETRAMETHYL)GUANIDINYL]PHOSPHINES

The tetramethylguanidinyl-substituted phosphines 3a-3c and 4a-4d were prepared by reaction of N,N,N',N'-tetramethylguanidine 1 (TMG) or N-trimethylsilyl-N',N',N'',N''-tetramethylguanidine 2 with RPCl, or RR'PCl. In the related reaction of MeAsCl, with 2 only the mono-substituted compound 5 was obtained. Typical phosphorus(III) reactivity was observed for the new phosphorus(III)-TMG compounds: e.g. in the reaction of 3a-3c, 4c and 4d with methyl iodide quaternisation took place (only at the phosphorus atom: no reaction at nitrogen was observed). The compounds 3a-3c and 4c react readily with sulfur, selenium and tellurium to form the corresponding chalcogenide derivatives. The oxidative addition of 9.10-phenanthraquinone to 3b led to the dioxa-lambda(5)-phosphole 12. Reaction of 2 with the chlorospirophosphorane (C5H4O2)(2)PCl gave the P tetramethylguanidinyl-substituted derivative 13. The X-ray structure determination of 4c, 8c and 9 shows short P-N bonds consistent with partial double bond character. Delocalisation involving the sulfur atom may enhance this double bond character leading to shorter P-N bonds in 8c and 9 than in 4c.