Synthesis and characterisation of new pyrazole–phosphinite ligands and their ruthenium(II) arene complexes

Abstract

The new potentially bidentate pyrazole–phosphinite ligands [(3,5-dimethyl-1 H-pyrazol-1-yl)methyl diphenylphosphinite] ( L 1 ) and [2-(3,5-dimethyl-1 H-pyrazol-1-yl)ethyl diphenylphosphinite] ( L 2 ) were synthesised and characterised. The reaction of L 1 and L 2 with the dimeric complexes [Ru(η 6-arene)Cl 2] 2 (arene = p-cymene, benzene) led to the formation of neutral complexes [Ru(η 6-arene)Cl 2(L)] (L = L 1 , L 2 ) where the pyrazole–phosphinite ligand is κ 1- P coordinated to the metal. The subsequent reaction of these complexes with NaBPh 4 or NaBF 4 produced the [Ru(η 6- p-cymene)Cl( L 2 )][BPh 4] and [Ru(η 6-benzene)Cl( L 2 )][BF 4] compounds which contain the pyrazole–phosphinite ligand κ 2- P,N bonded to ruthenium. All the complexes were fully characterised by analytical and spectroscopic methods. The structure of the complex [Ru(η 6- p-cymene)Cl( L 2 )][BPh 4] was also determined by a X-ray single crystal diffraction study.