Non-symmetric diphosphines based on the imidazole scaffold: an unusual group interchange involving Pd–CH3 and (imidazole)P–Ph cleavage

Abstract

Two regioisomeric, non-symmetric P^C2P^N-imidazoles, t-Bu₂PNCHCHNC(PPh₂) (L1, P^C2 = PPh₂, P^N = P(t-Bu)₂) and Ph₂PNCHCHNC[P(t-Bu)₂] (L2, P^C2 = P(t-Bu)₂, P^N = PPh₂), respectively, show dramatic differences in the reactivity of the N-bound phosphine group; the L2 isomer is extremely sensitive to P–N bond cleavage by nucleophiles, and when coordinated to the PdCl(Me) fragment it undergoes facile interchange of one P^N phenyl with the methyl originating from Pd.