Stereochemistry of low-spin cobalt porphyrins. 9. preparation and characterization of five-coordinate organocobalt(III) derivatives

Abstract

Organocobalt(III) derivatives have been prepared by direct aerial oxidation of tetraphenylporphinatocobalt(II) in solutions containing acetone, acetophenone, and malononitrile. The molecular and crystal structure of acetonyl-α, β, γ, δ-tetraphenylporphinatocobalt(III) has been determined by x-ray diffraction techniques. The porphinato core provides the base of a square pyramid, with the acetonyl group at the apex. CH 3C(O)CH 2CoTPP crystallizes in the triclinic system, space group P 1 . The unit cell has a = 12.187 (8) Å, b = 14.157 (5) Å, c = 11.925 (5) Å, α = 94.70 (2)°, β = 111.39 (4)°, and γ = 68.44 (4)°. The calculated and experimental densities are 1.356 and 1.34 g/cm 3 respectively for Z = 2, required crystal symmetry 1 . Final discrepancy indices are R 1 = 0.050 and R 2 = 0.076. The average Co-N distance is 1.948 Å and the Co-C distance is 2.028 Å.