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ORIGINAL PAPER

Synthesis, crystal structure, and spectroscopic characterization of two new binuclear complexes of manganese(II) and vanadium(V) with dipicolinate ligands containing 2-aminopyrimidinium as a counter cation Masoumeh Tabatabaee • Hamideh Mahmoodikhah • Ghassem Ahadiat • Michal Dusˇek • Michaela Pojarova´

Received: 23 March 2012 / Accepted: 22 October 2012 / Published online: 1 December 2012 Ó Springer-Verlag Wien 2012

Abstract Two new binuclear complexes, formulated as [(Hamp)[Mn(l-dipic)Cl(H2O)2]]2 and [(Hamp)[V(l-O)(O)(dipic)]H2O]2 (dipicH2 = pyridine-2,6-dicarboxylic (dipicolinic) acid; amp = 2-aminopyrimidine), were synthesized by a hydrothermal process and characterized by elemental analysis, IR spectroscopy, thermal analysis, and X-ray single crystal diffraction. Both compounds contain two Hamp cations and a dinuclear manganese(II) or vanadium(V) anion complex. In addition, the vanadium complex contains two lattice water molecules. Two manganese(II) ions are bridged by pyridine-2,6-dicarboxylate ions in the manganese complex, and they are both coordinated by O,N,O of the tridentate dipicolinate ligand, one oxygen of another dipicolinate ligand, one chlorine, and two water molecules in a distorted pentagonal-bipyramidal geometry. Vanadium(V) ions are coordinated octahedrally by O,N,O of the tridentate dipicolinate ligand, one oxo ion, and two bridging l-O ions in cis position in the vanadium complex. The crystal structures of both complexes are stabilized by a complex network of hydrogen bonds comprising water molecules, counter ion, and carboxyl groups of dipic2-. Keywords Metal complexes  Manganese complex  Vanadium complex  Dipicolinic ligand  Crystal structure

M. Tabatabaee (&)  H. Mahmoodikhah  G. Ahadiat Department of Chemistry, Yazd Branch, Islamic Azad University, Yazd, Iran e-mail: [email protected] M. Dusˇek  M. Pojarova´ Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Praha 8, Czech Republic

Introduction Binuclear complexes are of great interest because of their potential applications as magnetic materials and in catalytic and electron-transfer reactions. The importance of bi- or multidentate bridging ligands containing N- or O-donors follows from their ability to influence on the structures of coordination compounds. Two outstanding classes of bridging ligands containing polycarboxylate anions or polynitrogen are often used to bind metal centers in a number of multinuclear metal complexes. Among polycarboxylic acids, pyridine-2,6dicarboxylic (dipicolinic) acid (dipicH2) appears as a desirable ligand because of its low toxicity and amphiphilic nature [1]. Dipicolinic acid displays a large number of coordination modes because of the flexibility in relative position of its carboxylate groups and its nitrogen atom, acting as a bidentate, tridentate, and/or bridging ligand [2–5]. Manganese complexes with this ligand are rare in the literature [6–8], with only one known binuclear manganese(II) complex containing the bridging dipicolinate [8]. Vanadium complexes cont