Controlled Scrambling Reactions to Polyphosphanes Bond Metathesis Reactions

Triphosphanes R'PP(R)PR' (: R = Py; R = BTz), 1,3-diphenyl-2-pyridyl-triphospholane and pentaphospholanes (RP) (: R = Py; : R = BTz) are obtained in high yield of up to 98% from the reaction of dipyrazolylphosphanes RPpyr (: R = Py; : R = BTz; pyr = 1,3-dimethylpyrazolyl) and the respective secondary phosphane (R'PH, R' = Cy (), Bu (); PhPH(CH)PHPh ()). The formation of derivatives proceeds a condensation reaction while the formation of and can only be explained by a selective scrambling reaction. We realized that the reaction outcome is strongly solvent dependent as outlined by the controlled scrambling reaction pathway towards pentaphospholane . In our further investigations to apply these compounds as ligands we first confined ourselves to the coordination chemistry of triphosphane with respect to coinage metal salts and discussed the observation of different - and -isomeric metal complexes based on NMR and X-ray analyses as well as quantum chemical calculations. Methylation reactions of with MeOTf yield triphosphan-1-ium CyMePP(Py)PCy ( ) and triphosphane-1,3-diium CyMePP(Py)PMeCy ( ) cations as triflate salts. Salt [OTf] reacts with pentaphospholane in an unprecedented chain growth reaction to give the tetraphosphane-1,4-diium triflate salt CyMePP(Py)P(Py)PMeCy ([OTf]) a P-P/P-P bond metathesis reaction. The latter salt is unstable in solution and rearranges a rare [1,2]-migration of the CyMeP-group followed by the elimination of the triphosph-2-en-1-ium cation [CyMePPPMeCy] ( ) to yield a novel 1,4,2-diazaphospholium salt ([OTf]).