One-dimensional co-ordination polymer of aqua-bridged binuclear manganese(II) carboxylate W. Marjit Singh, Anirban Karmakar, Jubaraj B. Baruah * Department of Chemistry, Indian Institute of Technology, Guwahati 781 039, India Received 8 January 2008; accepted 17 February 2008 Available online 21 February 2008 Abstract A simple route for a novel sulphur containing one-dimensional aqua-bridged carboxylate co-ordination polymer of manganese(II) that have structural resemblance to biological aqua-bridged manganese systems is described. The manganese(II) co-ordination polymer is derived from dicarboxylate of (4-carboxymethoxy-2,3-bis-4-methylphenylsulfanyl-naphthalene-1-yloxy)-acetic acid and complex has pyridine as ancillary ligand. Ó 2008 Elsevier B.V. All rights reserved. Keywords: Polymeric aqua-bridged manganese complex; Sulphur containing dicarboxylic acid; One-dimensional co-ordination polymer; Crystal structure Aqua-bridged metal carboxylates (Fig. 1a) are found in some active sites of binuclear metallo-enzymes [1]. The binuclear aqua-bridged manganese compounds [2], are also studied as precursor of biological model compounds. Study of aqua-bridged binuclear transition metal complexes [3] are expected to increase understanding on the catalytic activity of metallo-enzymes [4]. There are large numbers of multinuclear manganese complexes [5] as well as other co-ordination polymers having binuclear paddlewheel type carboxylate units [6] are reported, but polymeric complexes with aqua-bridge manganese complexes are rare and only one grid like structure with rigid dicarboxylic acid [7] is reported. However, in biological system flexible one- dimensional co-ordination polymers of the type shown in Fig. 1b would be more relevant and they are not explored. We report here a one-dimensional co-ordination polymer that contains repeated units of aqua-bridged binuclear manganese carboxylates having close analogy to biological aqua-bridged metal carboxylates. The co-ordination polymer 4 shown in Scheme 1 was prepared by reacting disodium salt of (4-carboxymeth- oxy-2,3-bis-4-methylphenylsulfanyl-naphthalene-1-yloxy)- acetic acid (3) with manganese chloride in aqueous pyri- dine. The sodium salt of sulphur containing dicarboxylic acid namely (4-carboxymethoxy-2,3-bis-4-methylphenyl- sulfanyl-naphthalene-1-yloxy)-acetic acid was prepared by three steps procedure starting from 1,4-naphthoquinone as illustrated in Scheme 1. Thus, for the ligand synthesis, a diol precursor 2,3-bis-(4-methylphenylsulfanyl)-1,4-naph- thalenediol (1) was synthesised by reacting 1,4-naphthoqui- none with 4-methylbenzenethiol, which was further reacted with methylester of bromoacetic acid to obtain (4-meth- oxycarbonylmethoxy-2,3-bis-4-methylphenylsulfanyl-nap- thalene-1-yloxy)-acetic acid methyl ester (2). The methyles- ter (2) on hydrolysis gave the corresponding sodium salt (3). This sodium salt on reaction with manganese chloride in pyridine and water mixture gave a polymeric manganese complex (4) [8]. The co-ordination polymer (4) was obtained as colour- less block and it crystallises in a triclinic P  1 space group. The co-ordination polymer consists of repeated binuclear aqua-bridged manganese units. The binuclear units have also two carboxylate bridges. Each of these binuclear units is attached to one another by mono-dentate carboxylate (Fig. 2a) groups. The repeated units in the co-ordination 1387-7003/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2008.02.013 * Corresponding author. Tel.: +91 361 2582311; fax: +91 361 2690762. E-mail address: juba@iitg.ernet.in (J.B. Baruah). www.elsevier.com/locate/inoche Available online at www.sciencedirect.com Inorganic Chemistry Communications 11 (2008) 576–579