Preparation of cationic (E)-σ-alkenyi palladium complexes having a P–O–N or a P–O–P tridentate ligand as a stabilized intermediate of palladium-catalysed stereoselective addition of methanol to acetylenes; characterisation, X-ray analysis and the reaction pathway

Abstract

Cationic (E)-σ-alkenyl palladium complexes 1 having a P–O–N or a P–O–P tridentate ligand are prepared stereoselectively from cis-PdCl2(PNn= 1)[PN =o-Ph2PC6H4CH2O(CH2)n-2-C5H4N-P,N] or cis-PdCl2(POP)[POP = Ph2P(CH2)2O(CH2)2PPh2-P,P] and internal alkynes in the presence of AgPF6 and MeOH; the X-ray crystal structure of 1c is reported and a stepwise abstraction of chloride ligands for the formation of 1 is proposed.