The Structure of Pentakis(2-picoline N-oxide)cobalt(II) Perchlorate, [Co(C6H7NO)5](ClO4)2

The crystal structure of pentakis(2-picoline N-oxide)coball(II) perchlorate, [Co(C₆H₇NO)₅](ClO₄)₂, has been determined from X-ray counter data. The material crystallizes in the monoclinic space group C_2h⁵-P2₁/c, with a = 18.667 (7) Å, b = 10.444 (8) Å, c = 18.665 (7) Å, β = 96° 21 (1)′, Z = 4, d_obsd = 1.45 (5) g/cm³, and d_calcd = 1.48 g/cm³. A least-squares refinement gave a final conventional R factor of 0.091 for those 1611 reflections above background with values of λ^–1 sin θ > 0.3 Å^–1, whereas that for all 2293 independent reflections above background was 0.103. The compound consists of well-separated pentakis(2-picoline N-oxide)coball(II) and perchlorate ions. The immediate coordination about the cobalt atom for this d⁷ high-spin complex is essentially trigonal bipyramidal with the axial Co–O bond length greater than the equatorial bond length by 0.123 (9) Å.