Divergent behavior of palladium(II) and platinum(II) in the metalation of 1,3-di(2-pyridyl)benzene

1,3-Di(2-pyridyl)benzene undergoes regioselective orthometalation with Pd(OAc)(2) on the central ai yl ring, giving rise to a dimeric complex in which four acetate units act as bridges between two doubly metalated ligands and each pyridine ligand coordinates to a different metal atom. The reaction with chloride-containing Pd(II) complexes does not lead to C-H activation but to coordination complexes without Pd-C bonds. Cycloplatination of 1,3-di-(2-pyridyl)benzene takes place at C-2 of the benzene ring, generating a terdentate ligand. This behavior is the same as that previously observed for Ru and Os. Both orthometalated complexes have been structurally characterized by X-ray diffraction.