5,6-Membered palladium pincer complexes of 1-thiophosphoryloxy-3-thiophosphorylbenzenes. Synthesis, X-ray structure, and catalytic activity

Novel unsymmetrical ligands, 1-thiophosphoryloxy-3-thiophosphorylbenzenes 3a-d, bearing phosphine sulfide and thiophosphoryloxy moieties as coordinating sites, were found to undergo cyclometalation at the C-2 position of the central benzene ring in a reaction with bis(benzonitrile)palladium dichloride affording rare examples of nonsymmetrical pincer complexes, namely [2-{(thiophosphoryl)oxy}-6-(diphenylthiophosphoryl)phenyl]palladium chlorides 4a-d, containing 5- and 6-membered fused metallacycles with kappa3-SCS'-coordination. Molecular structures of the complexes were characterized by X-ray diffraction. These complexes demonstrated high catalytic activity for the Suzuki cross-coupling reactions of aryl bromides with phenylboronic acid.