Synthesis, Characterization, and Spectroelectrochemistry of Cobalt Porphyrins Containing Axially Bound Nitric Oxide

Several cobalt nitrosyl porphyrins of the form (T(p/m-X)PP)Co(NO) (p/m-X = p-OCH3 (1), p-CH3 (2), m-CH3 (3), p-H (4), m-OCH3 (5), p-OCF3 (6), p-CF3 (7), p-CN (8)) have been synthesized in 30−85% yields by reaction of the precursor cobalt porphyrin with nitric oxide. Compounds 1−7 were also prepared by reaction of the precursor cobalt porphyrin with nitrosonium tetrafluoroborate followed by reduction with cobaltocene. Compounds 1−8 have been characterized by elemental analysis, IR and 1H NMR spectroscopy, mass spectrometry, and UV−vis spectrophotometry. They are diamagnetic and display νNO bands in CH2Cl2 between 1681 and 1695 cm-1. The molecular structure of 1, determined by a single-crystal X-ray crystallographic analysis, reveals a Co−N−O angle of 119.6(4)°. Crystals of 1 are monoclinic, P2/c, with a = 15.052(1) A, b = 9.390(1) A, c = 16.274(2) A, β = 111.04(1)°, V = 2146.8(4) A3, Z = 2, T = 228(2) K, D(calcd) = 1.271 g cm-3, and final R1 = 0.0599 (wR2 = 0.1567, GOF = 1.054) for 3330 “observed” reflecti...