A different product distribution was formed when 1b was irradiated in the absence of TEMPO. Under these conditions formation of the Pd(I) complex 6 can be detected by P NMR (Scheme 6, c). Complex 6 gradually disappears with concomitant formation of ( t Bu3P)2Pd(0) over time, possibly due to a disproportionation side reaction. The latter complex eventually becomes the dominant species observable by 31 P NMR.