Reversible Insertion of Carbon Dioxide at Phosphine Sulfonamido PdII–Aryl Complexes

Phosphine sulfonamido Pd­(II) complexes bearing p-anisyl ([(P,N)­Pd­(4-OMe-C6H4)­L]; L = C5H5N, 5-py; L = OS­(CH3)2, 5-dmso) or carboxylato ([(P,N)­Pd­(OOCR)], 1-X: R = 4-OMe-C6H4, 1-pAn; R = tBu, 1-Piv; R = C6H5, 1-Ph) ligands were synthesized and their structures and dynamic behaviors were characterized. The compound 5-dmso can effectively be converted to 1-pAn by migratory insertion of carbon dioxide into the Pd–aryl bond with precoordination of the CO2 molecule. Additionally, carboxylato-substituted compounds 1-X can serve as catalysts for protodecarboxylation reactions of bis-o-OMe-substituted carboxylic acids at room temperature without the need for an external proton source. Stoichiometric decarboxylative coupling of these acids with styrene selectively yields 1,1-diarylated olefins.