Structure of a tetranuclear cobalt(II)-cobalt(III) complex of bis(2-hydroxyethyl)amine, [Co4{NH(C2H4OH)2} 2{NH(C2H4O)2}4](ClO 4)2

The structure of [Co₄(DetaH₂)₂(Deta)₄](ClO ₄)₂ (where DetaH₂ represents bis(2-hydroxyethyl)amine and Deta^2- represents the anion formed by removing two protons from bis(2-hydroxyethyl)amine) has been determined crystallographically and consists of tetranuclear cations and perchlorate anions. The compound crystallizes in the monoclinic space group P2₁/c with two formula units in a unit cell of dimensions a = 8.747 (2) Å, b = 17.408 (4) Å, c = 13.597 (3) Å, β = 111.45 (2)°, ρ_exptl = 1.80 g/cm³, and ρ_calcd = 1.82 g/cm³. The structure was solved by Patterson methods. Least-squares refinement converged at final values of R = 0.045 and R_w = 0.035 for 2719 reflections with I ≥ 2σ(I). The centrosymmetric tetranuclear cation contains two cobalt(III) ions, each coordinated by two tridentate Deta^2- ligands in a cis-facial arrangement. These Co(Deta)₂ ^- units bridge through the three oxygens of one face to the cobalt(II) ions; one oxygen coordinates both cobalt(II) ions, and each of the other two oxygens coordinates one of the cobalt(II) ions. The octahedral coordination of each cobalt(II) ion is completed by a bidentate (N,O) DetaH₂ ligand. Cobalt(III)-oxygen distances range from 1.888 (3) to 1.940 (3) Å; cobalt(III)-mitrogen distances are 1.968 (4) and 1.957 (4) Å. Cobalt(II)-oxygen distances range from 2.045 (3) to 2.225 (3) Å, and the cobalt(II)-nitrogen distance is 2.241 (4) Å.