THE DITHIOOXALATE-BRIDGED COMPLEX [CR(C2O2S2)3(NIL)3]-[CLO4]3 (L = RACEMIC 5,5,7,12,12,14-HEXAMETHYL-1,4,8,11-TETRAAZACYCLOTETRADECANE) - SYNTHESIS, CRYSTAL-STRUCTURE AND MAGNETISM

The reaction of KCa[Cr(C2O2S2)3].6H2O (C2O2S2 = dithiooxalate) and [NiL][ClO4]2 (L = racemic 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) in the 1:3 molar ratio gave a chromium(III)trinickel(II) complex [Cr(C2O2S2)3(NiL)3][ClO4]3. It crystallizes with two dimethylformamide and two Pr(i)OH molecules in the monoclinic space group C2/c, with a = 31.51 (1), b = 17.447(6), c = 19.05(1) angstrom, beta = 112.75(4)degrees and Z = 4. The complex has a CrNi3 core bridged by dithiooxalate groups which bond through sulfur atoms to the Cr and through oxygen atoms to the Ni. The Cr ... Ni separation is 5.959(5)-5.999(6) angstrom. The CrS6 entity shows a distortion to a trigonal-prismatic geometry. Each nickel ion assumes a pseudo-octahedral geometry with two oxygen atoms of the C2O2S2 group and four nitrogen atoms of L in a folded form. Cryomagnetic studies (4.2-300 K) revealed a ferromagnetic spin-exchange interaction between the Cr(III) and Ni(II) (J = +5.9 cm-1 based on H = -2SIGMAJ(ij)S(i)S(j)).