Crystal and molecular structure of the reversible dioxygen adduct of [NN′-4-methyl-4-azaheptane-1,7-diylbis(salicylideneiminato)]cobalt(II)

Abstract

The crystal and molecular structure of the title complex, [{Co(salmhpn)}₂]·O₂·2C₆H₆, has been determined from X-ray data collected by counter techniques. The compound crystallizes from benzene in space group P with cell parameters (at 293 K)a= 17.045(4), b= 12.697(3), c= 11.668(3)Å, α= 94.23(3), β= 90.06(3), γ= 100.43(3)°, and Z= 2. The structure has been refined to R= 0.087 and R′= 0.093 on the basis of 1 482 independent reflections. The crystal lattice contains both dioxygenated and non-dioxygenated molecules, in 1 : 1 ratio, in which the cobalt atoms are octahedral and five-co-ordinate respectively. In the dioxygenated molecules, the five-co-ordinating positions of the low-spin cobalt atoms are occupied by the donor atoms of the quinquedentate ligand salmhpn and the sixth position by a dioxygen molecule bound in a bent end-on fashion. The co-ordinated dioxygen molecule shows a two-fold statistical disorder and the interatomic O–O distances average 1.06(5)Å. The non-dioxygenated molecules, containing high-spin cobalt(II) atoms, do not show any appreciable interaction with the dioxygenated moieties. The shortest cobalt–cobalt distance is 7.54 Å. The crystal packing shows benzene molecules close to the co-ordinated dioxygen molecules.