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 Arash Ghorbani-Choghamarani a,⇑ , Ali Naghipour a , Fateme Heidarizadi a , Roghayeh Shirkhani b , Behrouz Notash c a Department of Chemistry, Faculty of Science, Ilam University, P.O. Box 69315516, Ilam, Iran b Faculty of Science, Omidiyeh Branch, Islamic Azad University, Omidiyeh, Iran c Department of Chemistry, Shahid Beheshti University, Tehran, Iran article info Article history: Received 24 December 2015 Received in revised form 19 February 2016 Accepted 22 February 2016 Available online 5 March 2016 Keywords: Phosphonium salt Palladium(II) acetate Amination reaction Stille cross-coupling reaction abstract The treatment of tri(p-tolyl)phosphine with 1,2-bis(bromomethyl)benzene results in (2-bromomethyl- benzyl)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 [(CH 3 C 6 H 4 ) 3 PCH 2 C 6 H 4 CH 2 OC(O)CH 3 ] 2 [Pd 2 Br 6 ], 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, 1 H, 31 P, 13 C 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 satis- factory results and could be recovered and reused without significant loss of its catalytic activity in both reactions. Ó 2016 Elsevier B.V. All rights reserved. 1. Introduction Triphenylphosphine and its derivatives are often used for the preparation of organic phosphines. They can easily react as nucle- ophiles with alkyl/aryl halides giving rise to phosphonium salts which are attractive due to their enhanced thermal stability [1]. Phosphonium salts are used in the preparation of phosphorus ylides, essential components in the Wittig reaction of alkenes syn- thesis [2]. Certain phosphonium salts are also used in biological researches as targeting agents and as pharmacological agents due to their anti-microbial activity against gram negative and positive bacteria [3]. These compounds have both lipophilic and cationic character, allowing them facile transport through cell wall or plasma membrane in order to accumulate in mitochondria of cells or cytoplasm [4]. For this reason as anti-cancer agents, they show great promise for diagnosis and treatment of tumor cells. Some of the phosphonium salts have demonstrated catalytic activity in a range of organic reactions including oxidation, polymerization and cross-coupling reactions [5,6]. Herein we describe the synthesis and characterization of a novel phosphonium salt containing tri(p-tolyl)phosphonium and hexabromodipalladate(II) moiety. Initially, this compound was successfully tested as a heterogeneous catalyst for the amination reaction of various aryl halides by aqueous ammonia as a nitrogen source under air atmosphere and solvent free conditions to pro- duce aniline and other primary aryl amines. Aniline and its deriva- tives are useful intermediates in producing dyes and pigments, agrochemicals, pharmaceuticals, etc. [7]. Direct utilization of ammonia in the preparation of aniline and its derivatives because of its low cost and availability is a desired approach [8,9]. Using this phosphonium salt containing hexabromodipalladate(II) as a heterogeneous catalyst in amination reaction of aryl halides with ammonia has several advantages, including direct utilization of ammonia, but not ammonia equivalents with initial protection and final deprotection [10], no need to argon or nitrogen atmo- sphere, dry ice, high temperatures and pressures, autoclave, and etc. [11,12], lack of by-products such as secondary and tertiary amines. http://dx.doi.org/10.1016/j.ica.2016.02.045 0020-1693/Ó 2016 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Tel./fax: +98 841 2227022. E-mail addresses: arashghch58@yahoo.com, a.ghorbani@mail.ilam.ac.ir (A. Ghorbani-Choghamarani). Inorganica Chimica Acta 446 (2016) 97–102 Contents lists available at ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica