Coupling of Alkynes on a Pd−Pd Bond to Generate an Electrophilicμ-Butenediylidene Moiety

The first dipalladium µ-PPh(3) complex (1) was obtained by the facile loss of two CH(3)CN ligands from [Pd(2)(PPh(3))(2)(CH(3)CN)(4)](PF(6))(2) in CH(2)Cl(2). Coupling of p-tolylacetylene (p-TolC identical withCH) with 1 or its precusor afforded the µ-butenediylidene complex 2, treatment of which with CH(3)CN resulted in PPh(3) migration to give 3.