FULL PAPER A One-Dimensional Manganese(II) Coordination Polymer Derived from Zerovalent Manganese and 1-Hydroxybenzotriazole  Synthesis, Characterization, Crystal Structure and Magnetic Properties Giannis S. Papaefstathiou, [a] Ramon Vicente, [b] Catherine P. Raptopoulou, [c] Aris Terzis, [c] Albert Escuer,* [b] and Spyros P. Perlepes* [a] Keywords: Coordination polymers / Nitrogen heterocycles / Magnetic properties / Manganese / X-ray crystal structure The reaction of zerovalent manganese with 1-hydroxybenzo- triazole, btaOH, and NH 4 SCN in DMF in the presence of di- oxygen allows isolation of the one-dimensional coordination polymer [Mn 3 (btaO) 2 (NCS) 4 (DMF) 8 ] n (3). X-ray diffraction analysis reveals that the chain is best described as [Mn 2 (btaO) 2 (NCS) 2 (DMF) 6 ] dimers linked by Mn(NCS) 2 - Introduction Over the last twenty years, we [1] and others [2] have been exploring the coordination chemistry of benzotriazole (btaH, Scheme 1) and its derivatives. The first reason for this is the anticorrosion properties of btaH and benzene ring-substituted benzotriazoles toward certain metals, par- ticularly copper and its alloys. [3] The second reason is the observation that reactions between metal β-diketonates or carboxylates and btaH or its ring-substituted (with non- donor groups) derivatives lead to incomplete replacement of β-diketonato or carboxylato ligands by the deprotonated benzotriazoles and the formation of large heteroleptic 3d- metal cages with unique structural motifs and exciting mag- netic properties. [1a,2b,2c] Thus, benzotriazolato ligands are amongst the most important in the field of high-nuclearity transition metal chemistry. Scheme 1 [a] Department of Chemistry, University of Patras, 265 00 Patras, Greece [b] Departament de Quı ´mica Inorga `nica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain [c] Institute of Materials Science, NCSR ‘‘Demokritos’’, 153 10 Aghia Paraskevi Attikis, Greece 2488  WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434-1948/02/0909-2488 $ 20.00+.50/0 Eur. J. Inorg. Chem. 2002, 2488-2493 (DMF) 2 bridges. Molar magnetic susceptibility measure- ments of 3 in the 5-300 K range indicate weak antiferromag- netic coupling between the Mn II atoms within the dinuclear subunits of the chain. ( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002) More recently, [4,5] our efforts have turned towards the use of benzotriazoles, substituted on the azole ring with donor groups, to see how incorporation of this ligand type might affect the structures and physical properties of the products. The first ligand employed was 1-hydroxybenzotriazole (btaOH, Scheme 1). The synthetic investigation of the [Cu 2- (O 2 CMe) 4 (H 2 O) 2 ]/btaOH reaction system in MeOH re- sulted in the isolation of the three-dimensional (3D), dia- mond-like polymeric complex [Cu(btaO) 2 (MeOH)] n (1), which is a soft magnet exhibiting two critical temperatures at 6.4 and 4.4 K. [4] Reaction of [Ni(NO 3 ) 2 ]·6H 2 O with btaOH in DMF/aqueous NH 3 has recently yielded the trin- uclear complex [Ni 3 (btaO) 6 (NH 3 ) 6 ](2). [5] In the present work, reactions of btaOH with zero-valent manganese were investigated. Zero-valent transition metals as starting materials are a good source for the construction of unusual polymeric and/or discrete metal complexes, which exhibit interesting magnetic properties and cannot be synthesised starting from conventional metal salts. [6] The subject of the present paper is the 1D coordination polymer [Mn 3 (btaO) 2 (NCS) 4 (DMF) 8 ] n (3) which is the product of the reaction between Mn 0 , btaOH and NH 4 SCN in DMF under aerobic conditions. Transition metal coordination polymers are of consider- able interest as magnetic, electronic and photooptical mat- erials. [7] Compounds with fascinating topologies and intric- ate interweaving of multiple networks have been discovered. Restricting further discussion to magnetic coordination polymers, we should mention that these molecular com- pounds may contain the same metal ion, two kinds of spin carriers (either two different metal ions or a metal ion and an organic radical) and, in a very limited number of cases,