Synthesis of new mixed-ligand cationic complexes of palladium [(acac)Pd(PPh3)(L)]BF4

Abstract

A selection of ligands, including mono-, bi-, and tridentate ones containing phosphorus, nitrogen, sulfur, oxygen, or a combination of them, is an important part of the practice of homogeneous catalysis of the reactions of unsaturated hydrocarbons by the transition metal complexes [1, 2]. While comparing the reactivity of neutral and cationic complexes, the preference was given to the latter [3, 4]. In a series of the transition metals, the palladium complexes are extensively used as active and selective catalysts for conversion of the unsaturated hydrocarbons over 50 years [5]. A common characteristic of the known synthetic methods of the cationic palladium complexes used as catalysts or components of catalytic systems is a multistage process and the use of expensive starting reagents including the silver salt of AgA type (where A is anion), thallium salts, or triphenylmethyl tetrafluoroborate [2, 6, 7]. In [8–10] we described a method for the synthesis of cationic palladium complexes [(acac) Pd(PAr3)2]BF4 in one stage by the reaction of Pd(acac)2, PAr3, and BF3OEt2 in 1:2:2 molar ratio. The testing of the catalytic system [(acac)Pd(PAr3)2]BF4/BF3OEt2 showed its high activity and selectivity (100%) in the process of styrene dimerization [8] and additive polymerization of norbornene [11].