Co-ordination chemistry and metal catalysed carbonylation reactions using 8-(diphenylphosphino)methylaminoquinoline: a ligand that displays monodentate, bidentate and tridentate co-ordination modes

Abstract

Reaction of (diphenylphosphino)methanol with 8-aminoquinoline gives a novel potentially tridentate ligand, 8-(diphenylphosphino)methylaminoquinoline. The co-ordination chemistry of this ligand has been studied. Reaction with [Cp*RhCl₂]₂ gave a P-monodentate complex that was characterised by X-ray crystallography. On addition of one equivalent of silver salts, a 50 ∶ 50 mixture of a tridentate dicationic complex and the starting material is formed. We describe this somewhat unusual co-ordination behaviour as 2/3 labile. If two equivalents of silver salts are used, the tridentate complex can be isolated and fully characterised. Iridium, ruthenium, palladium and platinum complexes are also described in which the ligand acts as mono- bi-, and tri-dentate. The ligand was also tested as a stabilising ligand in palladium and rhodium catalysed carbonylation reactions.