Cyanophosphine Derivatives: Nitrile or Cyanide Functionality?

Abstract

Treatment of dicyanophosphines R−P(CN)2 with 1 equiv of Schwartz's reagent, [Cp2Zr(H)Cl]n, led: (i) via a substitution reaction to the formation of the stable hydrocyanophosphines R−P(H)CN (R = Me, tBu, Mes*) or (ii) through a hydrozirconation reaction to the synthesis of the aldiminocyanophosphine R−P(CHNZrCp2Cl)CN (R = NiPr2). Further addition of 1 equiv of [Cp2Zr(H)Cl]n to R−P(H)CN (R = Me, tBu, Mes*) gave the primary phosphine R−PH2 (R = Me) or the aldimino secondary phosphine R−P(H)(CHNZrCp2Cl) (R = tBu, Mes*) after the hydrozirconation reaction. Interestingly, the dialdiminophosphorus compound R−P(CHNZrCp2Cl)2 (R = NiPr2) was obtained after addition of [Cp2Zr(H)Cl]n to R−P(CHNZrCp2Cl)CN (R = NiPr2). The difference in reactivity observed for the dicyanophosphines R−P(CN)2 with the metal hydride [Cp2Zr(H)Cl]n have been studied with the help of experimental analysis (UV−photoelectron spectroscopy, NMR, IR, X-ray) and computational methods.