CRYSTAL STRUCTURE OF TRANS-DIISOTHIOCYANATO-(5,7,7,12,14,14-HEXAMETHYL-1,4,8,11-TETRAAZACYCLOTETRA-DEA-4,11-DIENE) COBALT(III) THIOCYANATE. B. H. Chen¹, T. H. Lu², W. T. Huang¹, H. H. Yao¹, J. M. Lo¹, and C. S. Chung^{3 1}Department of Nuclear Science, ²Department of Physics, and ³Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 300, ROC

Transition-metal complexes of macrocyclic ligand containing asymmetric centers have been studied extensively, because of their particular stereochemistry. The crystal structure of trans-dichloro(c-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetraeca-4,11-diene) cobalt(III) perchlorate have been reported previously (Lu et al., J. Chin. Chem. Soc., 1992, 39, 343-345). Here we report crystal structure of the title complex. Orthorhombic, P2₁2₁2₁, a=12.169(2), b=13.576(1), c=14.929(1)Å, R=0.051, wR=0.055 for 2804 observed reflections. The Co(III) ion is six coordinated in a distorted octahedral geometry with the four N atoms of the two isothiocyanato group axials. The quadridentate macrocyclic ligand is in planar conformation with the two five-membered rings in gauche form and the two six-membered ring in twist form. The complex has the RR or SS configuration for the two chiral amine N centers. The intermolecular hydrogen bonds among the two NH groups and the unbonded thiocyanate ion help to stabilize the crystal structure.