Bis[(2-methylacetatobenzyl)tri(p-tolyl)phosphonium]hexabromodipalladate(II); synthesis, characterization, structural study and application as a retrievable heterogeneous catalyst for the amination of aryl halides and Stille cross-coupling reaction

Abstract

The treatment of tri(p-tolyl)phosphine with 1,2-bis(bromomethyl)benzene results in (2-bromomethylbenzyl)tri(p-tolyl)phosphonium bromide. The resulted phosphonium salt reacts with palladium acetate(II) in a molar ratio of 1.5:1, respectively, to give [(CH3C6H4)3PCH2C6H4CH2OC(O)CH3]2[Pd2Br6], bis[(2-methylacetatobenzyl)tri(p-tolyl)phosphonium]hexabromodipalladate(II), as a dark brown powder. Characterization of the obtained compound was performed by elemental analysis (CHN), IR, 1H, 31P, 13C NMR and X-ray crystallography techniques. This compound was found to be an efficient catalyst for the amination of aryl halides using aqueous ammonia to produce primary amines and for Stille cross-coupling reaction to produce biphenyl and its derivatives as well. Describe catalyst showed satisfactory results and could be recovered and reused without significant loss of its catalytic activity in both reactions.