Reactivity of cyclopalladated compounds. Part 11. Reactions of five-versus seven-membered cyclopalladated rings with phosphine ligands. Crystal structures of [(NMe2CH2C6H4)Pd{C(CF3)C(CF3)C6H4CH2NMe2}(PMe2Ph)] and [(NMe2CH2C6H4)Pd{C(CF3)C(CF3)C6H4CH2NMe2}(PMe2Ph)]

Abstract

trans- and cis-[([graphic omitted][graphic omitted]Me₂}] reacted with PMe₂Ph to give complexes [(NMe₂CH₂C₆H₄)[graphic omitted]Me₂}(PMe₂Ph)](2) and [([graphic omitted]d{C(CF₃)C(CF₃)C₆H₄CH₂NMe₂}(PMe₂Ph)](4) respectively which both contain only one phosphine per Pd atom and exist in a single isomeric form in the solid state. Both complexes have been characterized by X-ray diffraction studies. In compound (2) the phosphine has displaced the nitrogen atom of the orthometallated dimethylbenzylamine and is thus located trans to the nitrogen of the seven-membered organometallic ring. In compound (4), on the other hand, the phosphine has displaced the nitrogen atom of the seven-membered ring and is therefore trans to the σ-bonded carbon atom of the cyclopalladated dimethylbenzylamine ligand. Both compounds (2) and (4) exist as two isomers in solution which are in equilibrium with each other, the exchange rate being slow on the n.m.r. time-scale.