An investigation on the chemistry of the R2PP ligand: reactions of a phosphanylphosphinidene complex of tungsten(vi) with electrophilic reagents

Abstract

The nucleophilic properties of the title compound [(2,6-i-Pr₂C₆H₃N)₂(Cl)W(η²-t-Bu₂PP)]Li·3DME (1) were investigated in reactions with selected electrophilic reagents such as MeI, M(CO)₅THF (M = Cr, Mo, W), AlCl₃, and GaCl₃. Methylation of 1 by MeI yields phosphanylphosphido complexes [(2,6-i-Pr₂C₆H₃N)₂W(X)(1,2-η-t-Bu₂PP–CH₃)] (X = Cl, I) (2-Cl/2-I) with the formation of a new P–C bond. Moreover, 1 reacts with electrophilic compounds [(OC)₅M·THF] (M = Cr, Mo, W) to yield a series of novel dinuclear phosphanylphosphinidene complexes [(2,6-i-Pr₂C₆H₃N)₂(Cl)W(1,2-η-t-Bu₂PP–M(CO)₅)]Li·3DME (3, 4, 5) with very long P–M distances. Adducts [(2,6-i-Pr₂C₆H₃N)₂(Cl)W(1,2-η-t-Bu₂PP–MCl₃)]Li·3DME (6, 7) formed by reaction of 1 with GaCl₃ and AlCl₃ are labile and dissociate into 1 and MCl₃ (M = Ga, Al). The outcomes of reactions were monitored by ³¹P-NMR spectroscopy. Furthermore, the structures of the isolated complexes 2-Cl/2-I, 3, 4, and [(2,6-i-Pr₂C₆H₃N)₂(Cl)W(1,2-η-t-Bu₂PP–W(t-Bu₂PH)(CO)₃COLi·2DME] (5-P) were confirmed unambiguously by X-ray diffraction studies.