Crystal structure of tetraaqua-cis-bis(N-2-nitrobenzenesulfonylglycinato) manganese(II), Mn(H2O)4(C8H7N2O6S)2

Abstract

C 16H 22MnN 4 O 16S 2 ,monoclinic, P 121 / n 1(no. 14), a =7.7703(7) Å, b =7.7228 (7) Source of materialAmixture of Mn(CH 3 COO) 2 ·4H 2 O(0.5 mmol) and N -2-nitrobenzenesulfonylglycine (1 mmol, 2-NBS-GlyH)in10mLH 2 O was stirred about ten minutes to give aclear solution. Then the pH was adjusted to 6with 0.1 MNaOH solution.The reaction mixture was heated on awater bath for 6hupto65°C,and then filtered. Pink crystals of the title compound were separated from the mother liquor by slow evaporation at room temperature after 3 days. Experimental detailsWhile the hydrogen atoms attached to the carbon atoms were added geometrically, the water hydrogen atoms were found from Fourier difference maps and refinedfreely. DiscussionAmino acid is an important biological ligand. Itmay coordinate to the metal ions by the carboxylate or amino groups.Research on the coordination of metal-amino acid complexes has contributed to our understanding of the functionofmetal ions in organisms, interactions between amino acids and DNAare of great importance in biochemistry [1][2][3][4][5].Moreover N -sulfonyl amino acids were found to reproduce the coordination behavior of peptides and their selectivitytowards metal ions [6][7][8][9][10]. Thus, it is of great interest in studying the coordination chemistry of N -sulfonylglycineacid. Onthe other hand, in recent years, there has been considerable interest in the design and synthesis of manganese(II) complexes. The main reason may be that these complexes can be used for investigation of the exchange coupling interactions between metal ions, as well as for anew variety of molecular-based magnetic materials [11][12][13].Furthermore,m anganese(II)i on plays an important role in several biological redox-active systems, for example, manganese catalase, manganese superoxide dismutase and oxygen-evolving complexes (OEC)o fp hotosystem II in green plants [14]. X-ray analysis reveals that the title crystal structure consists of mononuclear complex molecules( figure, top). The 2-NBS-Gly ligand acts as an anion in the complex. The coordination environment around the Mn(II)i on can be described as as eriously distorted octahedron with three trans angles ranging from 83.61(9)°to 170.80(10)°, whereas each Mnion is six-coordinated by two carboxylate Oatoms from two different 2-NBS-Gly ligands and four water Oatoms. The Mn-O(water) bond lengths are 2.128(2)Å-2.163(2) Å,and the Mn-O(carboxylate) bond lengths are in the range of 2.156(2) Å-2.288(2) Å,respectively, which are in the normal range of those observed in manganese(II) carboxylate complexes. The two carboxylate groups of 2-NBSGly ligands displayt he same coordination mode. The carboxyl group coordinates to the Mn(II)ion in amonodentate mode. Hydrogen bonding appears to be akey factor in defining the molecular packing, and the large network of intermolecular hydrogen Z.Kristallogr