CRYSTAL AND MOLECULAR-STRUCTURE OF THE PEROXO-BRIDGED DIMER ((TRENEN)COO2CO(TRENEN)) (CLO4)4 WHERE TRENEN = N,N,N'-TRIS(2-AMINOETHYL)-ETHANE-1,2-DIAMINE

The preparation and crystal structure of the brown crystalline cobalt(III) dimer [(trenen)CoO2-Co(trenen)](ClO4)4 is described where the pentadentate ligand trenen is N,N,N'-tris(2-aminoethyl)ethane-1,2-diamine. The compound forms monoclinic crystals with a 13.132, b 14.214, c 8.906 angstrom and beta 91.53-degrees, and two formula units in the unit cell, in space group P2(1)/n. The nitrogen atoms of the trenen ligand occupy five of the six slightly distorted octahedral sites about each cobalt atom with a peroxo bridge linking the two Co(trenen) moieties through the sixth site. The Co-O-O-Co dihedral angle is 180-degrees, the molecule possesses a centre of symmetry, and the peroxo bridging group is situated trans to the secondary nitrogen atom attached to each cobalt atom (the s,s-isomer). The electronic spectrum displays a strong (epsilon 13700 dm3 mol-1 cm-1) absorption band at 302 nm which is typical of peroxo-bridged dicobalt complexes with a single transplanar CoO2Co bridge.