New strategies to phosphino-phosphonium cations and zwitterions.

By employing strategies based on frustrated Lewis pair chemistry, new routes to phosphino-phosphonium cations and zwitterions have been developed. B(C(6)F(5))(3) is shown to react with H(2) and P(2)tBu(4) to effect heterolytic hydrogen activation yielding the phosphino-phosphonium borate salt [(tBu(2)P)PHtBu(2)] [HB(C(6)F(5))(3)] (1). Alternatively, alkenylphosphino-phosphonium borate zwitterions are accessible by reaction of B(C(6)F(5))(3) and PhC[triple chemical bond]CH with P(2)Ph(4), P(4)Cy(4), or P(5)Ph(5) affording the species [(Ph(2)P)P(Ph)(2)C(Ph)=C(H)B(C(6)F(5))(3)] (2), [(P(3)Cy(3))P(Cy)C(Ph)=C(H)B(C(6)F(5))(3)] (3), and [(P(4)Ph(4))P(Ph)C(Ph)=C(H)B(C(6)F(5))(3)] (4). A related phosphino-phosphonium borate species-[(Ph(4)P(4))P(Ph)C(6)F(4)B(F)(C(6)F(5))(2)] (5) is also isolated from the thermolysis of B(C(6)F(5))(3) and P(5)Ph(5).