Crystal structure of a cobalt(III) macrocyclic Schiff-base complex

Abstract

The crystal structure of the Schiff-base complex dicyano-5,7,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclo-tetradeca-4,14-dienecobalt(III) perchlorate, [Co(C₁₆N₄H₃₂)(CN)₂]ClO₄, has been determined from three-dimensional X-ray data collected photographically at room temperature. The crystals are orthorhombic, space group Pbca, with Z= 8 in a unit cell of dimensions a= 12·20(2), b= 21·28(5), and c= 18·45(3)Å. The structure has been refined by least-squares techniques to R 9·9%. The stereochemical arrangement about the central cobalt atom is approximately octahedral, with cyanide groups above and below the macrocycle. The four nitrogen atoms of the quadridentate ligand are displaced significantly out of a least-squares plane through them, with an approximate mirror plane (not required crystallographically) perpendicular to the macrocycle through the centre of the cation. Oxygen atoms in the perchlorate anion show considerable anisotropic thermal motion.