Abstract
The influences of perturbations of supporting phosphine ligands on the dehydrative decarbonylation of (L-n)Pd-II (Cl)-hydro-cinnamoyl complexes (L = (PBu3)-Bu-t, n = 1; L = PPh3, n = 2; L = dppe, n = 1) to yield styrene were studied through combined experiment and theory. Abstraction of chloride from the complexes by silver and zinc salts, as well as sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, enhanced the efficiency of styrene formation, according to the following trend in L: (PBu3)-Bu-t > dppe > PPh3. DFT calculations corroborated the experimental findings and provided insights into the ligand influences on reaction step barriers and transition state structures. Key findings include the following: a stable intermediate forms after chloride abstraction, from which beta-hydride elimination is most affected by ligand choice, the low coordination number for the (PBu3)-Bu-t case lowers reaction barriers for all steps, and the trans disposition of two ligands for L = PPh3 contributes to the low efficiency for styrene production in that case.