Formation of a vinyliminium palladium complex by C-C coupling in vinylcarbene palladium aryl complexes

Pentafluorophenyl palladium complexes 3 and 5 bearing a vinylcarbene ligand slowly decompose on heating by migratory insertion to give Pd(O) and the vinyliminium salts (Et2N=C(C6F5)CH=CHPh)X (X = Br, BF4). However, the presence of triphenylphosphine in complex 4 stabilizes 7, a compound with a C=C Pd-bound vinyliminium moiety, where there is a strong preference for the C=C versus the C=N coordination.