ELSEVIER Inorganica Chimica Acta 230 (1995) 219-223 Synthesis of polymer- complexes Note and silica-supported manganese phosphine and their reaction with oxygen Guang Qing Li, Rakesh Govind * Department of Chemical Engineering, University of Cincinnati, Cincinnati, OH 45221, USA Received 3 May 1994; revised 20 July 1994 Abstract A series of polymer- and silica-supported manganese phosphine complexes has been prepared and characterized. These complexes react reversibly with molecular oxygen in the solid state to yield 1:1 Mn:O2 adducts. The reaction may be reversed either by a pressure drop or a temperature rise. All the 02 adducts are highly colored and binding curves as a function of the partial pressure of oxygen have been constructed. The silica-supported complexes can be prepared from ligand-silanes either by reaction with dehydrated silica and then with anhydrous manganese(II) bromide or vice versa. Keywords: Manganese complexes; Phosphine complexes; Dioxygen complexes; Silica-supported complexes; Polymeric complexes 1. Introduction Many highly active and selective catalysts can be derived from transition metal complexes and the prop- crties of these catalysts may often be varied widely by a change in the electronic and steric environment of the metal center. However, these homogeneous catalysts are often more difficult to handle than heterogeneous catalysts. On an industrial scale, problems associated with homogeneous catalysts include corrosion, depo- sition of the catalyst on the wall of the reactor and expensive recovery of the catalyst from the reaction products. One way of overcoming these problems while retaining the advantages of the transition metal complex catalysts is to anchor homogeneous catalysts to polymers or other supports effectively 'heterogenizing' them, and this technique is currently attracting widespread interest [1]. In recent years there has been a rapid growth in the use of supporting transition metal complexes mainly as catalysts for hydrogenation, hydroformylation, hy- drosilylation and isomerization reactions [2]. Apart from the obvious advantage of ease of recovery, the thermal stabilities of such complexes are frequently higher than those of their homogeneous counterparts and they are often less sensitive to oxidation and moisture. * Corresponding author. Our interest in manganese(II) tertiary phosphine complexes stems from the fact that they are able reversibly to bind dioxygen and other small molecules either in the solid state or in solution [3,4]. This reversibility of the 02 binding appears to have potential as a practical means as an oxidation catalyst and as an absorbent for removing oxygen from air. In an effort to improve the chemical robustness of the complexes we have synthesized a number of polymer- and silica- supported manganese phosphine complexes. 2. Results and discussion The ligand-polymers were synthesized by the reaction of LiPR2 (R = Me, Ph) with the corresponding polyvinyl chloride (PVC) and poly-p-bromostyrene (PBS). Ele- mental analyses of the products indicated that the reactions proceeded nearly to completion with typically only a small amount of residual chlorine or bromine ( < 0.1%) remaining on the polymer. The phosphinated polymers were then reacted with the manganese(II) salts, MnX2 (X=C1, Br or I), in a 1:1 molar ratio in anhydrous solvent in an inert atmosphere to give the supported complexes (Scheme 1 and Table 1). Liganding groups can be chemically bonded to the surface of macromolecules. Thus transition metal com- plexes may be prepared which are highly dispersed on 0020-1693/95/$09.50 © 1995 Elsevier Science S.A. All rights reserved SSDI 0020-1693(94)04294-6