Interaction of Dioxygen with Nitrosyl Complexes of meso-Mono- 4(3)-pyridyltriphenylporphyrinatocobalt(II) in Sublimed Layers

Sublimed layers of 5-(pyridin-4-yl)-10,15,20-triphenylporphyrinato)cobalt(II) and 5-(pyridin-3-yl)-10,15,20triphenylporphyrinato)cobalt(II) ({Co(M4PyTPP)} (I) and {Co(M3PyTPP)} (II), respectively) form coordination oligomers upon standing. Interaction of NO(15NO) gas with these systems results in the formation of pentaand hexacoordinated nitrosyl complexes, the sixth coordination site of which is occupied by pyridyl group of adjacent molecule in the layer. The FTIR spectral data demonstrate that the long-term exposure of these systems under O2 results in oxidation of the nitrosyl complexes with formation of hexacoordinated nitrato complexes and the reaction proceeds predominantly with hexacoordinated nitrosyls. Мechanism of oxidation more likely includes the dissociation of NO from the hexacoordinated complex followed by O2 trapping of resulting (-4(3)Py)Co(M4(3)PyTPP) to give (4(3)Py) Co(M4(3)PyTPP)(O2), which then reacts rapidly with NO by the nitric oxide dioxygenation reaction.