Cationic methallylnickel complexes with chelating ligands: A new dynamic complex isomerization equilibrium

Article abstract of DOI:10.1021/om00011a055

The synthesis of the cationic complexes [methyl 2-(diphenylphosphino)benzoate-κ²P,O]-(η ³-methallyl)nickel(II) tetrafluoroborate (1), [methyl 2-(diphenylphosphino)nicotinate-η²P,N]-(η ³-methallyl)nickel(II) tetrafluoroborate (2), and bis[μ-2-(diphenylphosphino)pyridine-κ²P,N]bis(η ³-methallyl)nickel(II) bis(tetrafluoroborate)·CH₂Cl₂ (3) are reported. The crystal structures of 1 and 2 have been disclosed in a preliminary previous paper. The molecular structure of the cation of 2 in the crystal shows that the ligand forms a strained 4-membered ring with a κ²P,N coordination. In solution a new dynamic complex isomerization was found, indicating an equilibrium between 2 and 4, the latter with a 6-membered ring and a κ²P,O coordination of the ligand methyl 2-(diphenylphosphino)nicotinate (5).