As Pd(OAc)2 is converted to the Pd(I) dimer [Pd(I)(P t Bu3)]2 upon exposure to formate, Bu4NI and P t Bu3•HBF4 (eq. 1), use of Pd(OAc)2 as a precatalyst in the coupling of 1a with 2a was explored in the presence and absence of P t Bu3 (eq. 2). Although somewhat lower yields of 3a were obtained, substantial quantities of 3a were formed in the absence of P t Bu3, demonstrating P t Bu3 is not required for catalysis and may simply enhance efficiency by stabilizing offcycle species. Similarly, the coupling of 1a with 2a was conducted using the Pd(II) dimer [Pd2I6][NBu4]2 in the presence and absence of P t Bu3 (eq. 3). Here, conversion to 3a corroborates the catalytic competence of iodide-bridged Pd(II) dimers and again shows that phosphine-ligated palladium catalysts are not required. Upon exposure of [Pd(I)(P t Bu3)]2 (100 mol%) to Bu4NI (400 mol%), free P t Bu3 was detected by 31 P NMR and the dianionic Pd(I) dimer [Pd2I4][NBu4]2 was detected by ESI-HRMS (eq. 4). While the collective data implicate [Pd2I4][NBu4]2 as the active catalyst (eq. 1-4), superior efficiencies were observed using [Pd(I)(P t Bu3)]2, which was selected to survey reaction scope.