A facile route to cis-olefin-linked phosphino-phosphonium salts of the form: [Ph2PC(R)C(H)P(R′)2H][AlCl4]

Abstract

The diphenylphosphirenium salts of the form [Ph₂PC(R)C(H)][AlCl₄] are readily generated and select examples react with secondary phosphines, R₂PH, to give dissymmetric bidentate phosphonium salts, [Ph₂PC(R)C(H)P(R′)₂H][AlCl₄]. While these reactions work well for sterically encumbered combinations of the phosphirenium cations and secondary phosphines (R = tBu, Cy, Mes), less encumbered combinations provide a mixture of products arising from alkyne displacement. As expected the protonated bis-phosphine salts are easily deprotonated, demonstrating easy access to a rare class of dissymmetric bidentate phosphine ligands.