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(C6F5)(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(C6F5)(3)] (1). Alternatively, alkenylphosphino-phosphonium borate zwitterions are accessible by reaction of B(C6F5)(3) and PhC CH with P2Ph4, P4Cy4, or P5Ph5 affording the species [(Ph2P)P(Ph)(2)C(Ph)=C(H)B(C6F5)(3)] (2), [(P3Cy3)P(Cy)-C(Ph)=C(H)B(C6F5)(3)] (3), and [(P4Ph4)P(Ph)C(Ph)=C(H)B(C6F5)(3)] (4). A related phosphino-phosphonium borate species-[(Ph4P4)P(Ph)C6F4B-(F)(C6F5)(2)] (5) is also isolated from the thermolysis of B(C6F5)(3) and P5Ph5.