Synthesis, crystal structure and magnetic properties of a new heterotetranuclear copper(Il)-manganese(II) complex

A new complex [Mn(CuL)(3)] [Mn(H2O)(6)][N(CN)(2)](2)(ClO4)(2) 4H(2)O (L = 1,4,8,11-tetraazacyclotetradecane-2, 3-dione) has been synthesized and structurally characterized by X-ray diffraction. The complex crystallizes in monoclinic, space group C2/c with a = 22.295(5), b = 12.852(3), c = 20.109(4) Angstrom, beta = 90.47(3)degrees and Z = 4. Three neutral copper(II) complexes of tetraazamacrocyclic oxamide coordinate to the manganese(II) ion with six carbonyl oxygen atoms with the Mn-O bond distances ranging from 2.190(6) to 2.208(5) Angstrom. Perchlorate anions are posited within the layers formed by the regular arrangement of [Mn(CuL)(3)](2+) moieties. The oxygen atoms of perchlorate ions semi-coordinate to copper(II) (Cu-O: 2.902 to 2.996 Angstrom) and link the [Mn(CuL)(3)](2+) units, generating a two-dimensional structure. [Mn(H2O)(6)](2+), dca(-) (dicyanamide anion) and water are distributed between the layers to form many H-bonds which connect the layers into a three-dimensional network. Magnetic studies show the presence of antiferromagnetic interaction between the Cu(II) and Mn(II) ions. Best fit to the experimental data by using the Hamiltonian (H) over cap = -2J(MnCu)(S) over cap (Mn)((S) over cap (Cu1) + (S) over cap (Cu2) + (S) over cap (Cu3)) gives the coupling constant J(MnCu) of -17 cm(-1).