From the above results, the size of the monophosphine appears to affect the extent of OAC formation at equilibrium. A plot of yield versus the corresponding ligand buried volume (%Vbur) indeed indicates a sharp drop in OAC yield for ligands with %Vbur > ca. 57% (see ESI, Figure ). Not surprisingly then, mixtures of 2 with t-BuBrettPhos (%Vbur = 57.7) or AlPhos (%Vbur = 74.3) did not yield appreciable amounts of OAC at room temperature (see ESI, Figures ); refluxing the solutions led to Pd black formation. Nevertheless, many monodentate ligands used in catalysis feature %Vbur values below this threshold and bidentate ligands do not suffer this limitation. This approach should thus provide a modular route to a variety of Pd OACs. ) was also prepared. The effect of halide identity on OAC formation was examined and had little effect on the yields of OAC formation (see ESI, Scheme S2). Bromo complex 2 and iodo complex S2 (see ESI, Tables S7-S11 and S13) also performed similarly in catalytic applications. However, the relative stability in CH2Cl2 solution at room temperature favors the bromo palladate.