CRYSTAL AND MOLECULAR-STRUCTURE OF A MANGANESE COMPLEX OF TRANS-1,2-DIAMINOCYCLOHEXANE-N,N,N',N'-TETRAACETIC ACID (CDTA) - MN4(CDTA)2(H2O)9(CH3COCH3)0.5. EVIDENCE FOR A MN7(CDTA)4(H2O)8 UNIT

The crystal structure of Mn4(CDTA)2(H2O)9(CH3COCH3)0.5 has been determined by X-ray diffraction methods. It crystallizes in the trigonal system, space group P3(2)21, with lattice parameters: a = 18.978(9) angstrom, c = 22.916(10) angstrom and Z = 6 formula units. The structure consists of a threedimensional network, built up with Mn7(CDTA)4(H2O)8 units. These units are connected through bismonodentate acetate bridges. In a Mn7 unit, the metal atoms are connected through Mn-O-Mn bridges resulting in metal-metal distances between 3.67 angstrom and 3.82 angstrom. The CDTA conformation is E, G/R and the cyclohexane ring is in a chair conformation. There are five crystallographically independent manganese atoms; three of them have a rather regular octahedral surrounding and two others are heptacoordinated by the CDTA ligands in a monocapped octahedron and a monocapped trigonal prism, respectively.