Structural study of a new type of B12 model involving a non-symmetrical equatorial ligand; aquaethyl[N,N′-ethylene(acetylacetonylideneiminato)-(salicylideneiminato)]cobalt(III)

Abstract

An X-ray crystal structure determination has been performed for a new type of B₁₂ model involving a non-symmetrical equatorial ligand. Aquaethyl[N,N′-ethylene(acetylacetonylideneiminato)-(salicylideneiminato)]cobalt(III) crystallizes in the triclinic space group P with two formula units in a cell having the dimensions a= 9.366(1), b= 11.292(2), c= 8.009(1)Å, α= 99.10(1), β= 102.48(2), and γ= 82.60(1)°. The co-ordination about the cobalt atom is that of a distorted octahedron. The equatorial co-ordination sites are occupied by the N₂O₂ donors from the non-symmetrical Schiff base. A water molecule occupies an axial position with a transσ-bonded ethyl group. Comparison with other types of B₁₂ models shows that the present complex is characterized by high values of three structural parameters, i.e. the Co–O axial bond length, the dihedral angle between the two halves of the equatorial ligand, and the displacement of the cobalt atom out of the mean plane of co-ordination. These structural features are discussed in relation with other ground-state properties and with the behaviour of the Co–C bond.