Synthesis of Ru(II) complexes of the new 1-[(P-diphenyl)-2-phosphinoethyl]-3,5-dimethylpyrazole ligand and study of their reactivity toward terminal alkynes

Abstract

The reaction between [RuCl 2(PPh 3) 3] and one or two equivalent amounts of 1-[(P-diphenyl)-2-phosphinoethyl]-3,5-dimethylpyrazole ( 1) in dichloromethane gave [RuCl 2(PPh 3)( 1)] ( 2) or [RuCl 2( 1) 2] ( 3), respectively, in good yields. Activation of propargylic alcohol derivatives by 3 in refluxing dichloromethane and in the presence of NaBPh 4 lead to the new allenylidene ruthenium complexes [RuCl( 1) 2(CCCPhCH 3)][BPh 4] ([ 4][BPh 4]) and [RuCl( 1) 2(CCCPh 2)][BPh 4] ([ 5][BPh 4]). The reaction between 3 and phenylacetylene in dichloromethane and in the presence of KPF 6 affords the vinylidene complex [RuCl( 1) 2(CCHPh)][PF 6] ([ 6][PF 6]). The X-ray diffraction studies of 2, 3, and [ 5][BPh 4] are reported.