Synthesis, characterization and catalytic activity of a new peroxomolybdenum(VI) complex-based coordination polymer M. Afsharpour a , A.R. Mahjoub a, * , M.M. Amini b a Department of Chemistry, Tarbiat Modares University, 14155-4838 Tehran, Iran b Department of Chemistry, Shahid Beheshti University, 1983963113 Tehran, Iran Received 20 February 2007; received in revised form 3 May 2007; accepted 3 May 2007 Available online 10 May 2007 Abstract A new form of polymeric compound of molybdenum, [MoO(O 2 ) 2 .4,4 0 -bipy] n , was synthesized by a simple and inexpensive route and characterized by infrared, ultraviolet, nuclear magnetic resonance spectroscopes and thermal analysis. The prepared catalyst was used for the epoxidation of cyclohexene and cyclooctene in a heterogeneous system at room temperature. Results showed that the new form of MoO 5 complex has significant potential as an oxidant in oxygen atom transfer reactions. This reagent oxidized olefins to epoxides in the presence of hydrogen peroxide with high conversions and selectivity. Effects of temperature, amount of catalyst, hydrogen peroxide and solvent in the epoxidation of substrate have been investigated. The stability of catalyst in epoxidation reactions has been investigated in homogenous system by recovering catalyst and recycling. Results showed that catalyst can be used at least for five consecutive cycles without a significant drop in yield. # 2007 Elsevier B.V. All rights reserved. Keywords: Heterogeneous catalysts; Peroxo molybdenum; Epoxidation 1. Introduction In recent years, switching catalytic process from homogenous catalytic system to heterogeneous system attracted considerable amount of interest in the chemical industry. Although high selectivity, activity and low loading are advantages of the homogenous catalytic system in the production of fine chemicals, the final cost usually is high [1,2]. The separation of expensive catalyst from the reaction mixture is probably the most burdening cost in the production of chemicals in a homogenous system. In addition, often during the separation of the catalyst part, it decomposes and adds additional cost to production. Therefore, interest on immobilization of the catalyst in various chemical industries is continuing to thrive [3]. Many approaches were used to immobilize catalysts [1–4]. Among them grafting metal complexes to supports via a covalent bond is the most popular approach for the heterogenization; and three types of immobi- lization by covalent bond of ligand have been recognized. In the classical method, the catalyst is randomly immobilized on the surface of organic or inorganic polymers. They are usually prepared by the polycondensation of monomeric functionalized ligands that coordinated to the metal complexes as the active substance, or by grafting catalyst on the polymeric support through condensation or coordination [4–8]. These supported catalysts often have lower activity than homogeneous forms. In the second approach, the catalysts are incorporated on the main chain of polymers [9,10]. Probably the main advantage for these supported catalysts is the low leaching. The third type is called coordination polymer catalysts, which metal complex links to another one by bridging ligand and one-, two- or three- dimensional polymer forms. [11–15]. Coordination polymer catalysts usually exhibit high conversion and selectivity, and they have good chemical and thermal stability in addition to the low solubility in the common solvents. Peroxo complexes of Mo(VI) in the form of oligomers are well known and have been characterized quite a long time ago and used widely in the epoxidation of alkenes by employing various ligands [16–33]. As a contribution to this interesting class of compounds as catalysts, we reported here the synthesis of a new peroxomolybdenum(VI) complex with N, N- bridging ligand (4,4 0 -bipyridine) and explored its application as a heterogeneous catalyst in the epoxidation of alkenes in a very www.elsevier.com/locate/apcata Applied Catalysis A: General 327 (2007) 205–210 * Corresponding author. Tel.: +98 21 88011001; fax: +98 21 88009730. E-mail address: mahjouba@modares.ac.ir (A.R. Mahjoub). 0926-860X/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.apcata.2007.05.013