Naphthyl-Based PCP Platinum Complexes. Nucleophilic Activation of Coordinated CO and Synthesis of a Pt(II) Formyl Complex

A series of naphthyl-based PCP Pt(II) complexes was synthesized and characterized. A single-crystal X-ray study of (PCP)PtCl ( 2 ) reveals stacking of the aromatic units between each pair of molecules of 2 . Chloride abstraction from 2 under nitrogen atmosphere leads to formation of the unsaturated cationic complex [(PCP)Pt] + BF 4 - ( 3 ), with the metal center being stabilized by the counteranion ( 3a ) or by the solvent ( 3b ). Abstraction of the chloride ligand from 2 under CO atmosphere leads to formation of the cationic carbonyl complex [(PCP)Pt(CO)] + BF 4 - ( 4 ), containing an electrophilic carbonyl ligand. The latter is attacked by nucleophiles (MeO - and H - ) to give the platinum carbomethoxy complex 5 and a rare platinum formyl complex, 6 . Stabilized by the bulky bis-chelating tridentate pincer-type system, the formyl complex 6 was isolated and characterized. Complex 6 is more stable than the previously reported platinum formyls. At room temperature complex 6 is slowly converted (during days) into a hydride complex, 7 .