Synthesis and Reactivity of a Platinum(II) Complex with a Chelating Dehydro(arylboronic anhydride) Ligand. Transmetalation of Arylboronic Acid

The reaction of ArB(OH)₂ (Ar = C₆H₄OMe-4, Ph, C₆H₄COMe-4) with PtI₂(dppe) in THF in the presence of Ag₂O and H₂O at room temperature produced a Pt complex with a chelating dehydro(arylboronic anhydride) ligand, (1a, Ar = C₆H₄OMe-4; 1b, Ar = Ph; 1c, Ar = C₆H₄COMe-4). The complexes were characterized by NMR spectroscopy and X-ray crystallography. Reactions of protonic acids, such as HCl, CF₃COOH, and CH₃COOH, with 1a yielded complexes with chloro and carboxylate ligands, PtX₂(dppe) (2, X = Cl; 3, X = OCOCF₃; 4, X = OCOMe). The complexes 1a−c react with arylboronic acids bearing the same aryl group as the ligands of the complexes to form diarylplatinum complexes, PtAr₂(dppe) (5a, Ar = C₆H₄OMe-4; 5b, Ar = Ph; 5c, Ar = C₆H₄COMe-4), respectively. Reactions of 4-MeCOC₆H₄B(OH)₂ with 1b and of PhB(OH)₂ with 1c in 2:1 molar ratios form mixtures of three diarylplatinum complexes in a statistical ratio.