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

Abstract

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 8.906Ǻ and β 91.53°, and two formula units in the unit cell, in space group P2₁/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°, 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 (є 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.