Phosphinimine–borane combinations in frustrated Lewis pair chemistry

Abstract

The phosphinimines Ph(3)PNR (R = Ph 1, C(6)F(5) 2, tBu 3) are combined with B(C(6)F(5))(3) in an effort to explore the frustrated Lewis pair (FLP) chemistry. While compound 1 is shown to form an adduct with the borane, compounds 2 and 3 exhibit no apparent interaction. Nonetheless exposure of each of the three combinations to H(2) resulted in the formation of the corresponding salts [Ph(3)PN(H)R][HB(C(6)F(5))(3)] (R = Ph 5, C(6)F(5) 6, tBu 7). Reaction of 1 or 2 with B(C(6)F(5))(3) and carbon dioxide afforded Ph(3)PN(R)COOB(C(6)F(5))(3) (R = Ph 8, C(6)F(5) 9) while the corresponding reaction with 3 gave rise only to the tBuNCO and (Ph(3)PO)B(C(6)F(5))(3). Reactions of 1-3 and B(C(6)F(5))(3) with PhC≡CH proceeds to give either deprotonation or addition affording products of the form [Ph(3)PN(H)R][PhC≡CB(C(6)F(5))(3)] or (Ph(3)PNR)(Ph)C=CH(B(C(6)F(5))(3)). The factors governing the nature of the dominant products are considered.