Cobalt porphyrins nitrosyl complexes

Nitric oxide and iron nitrosyl complexes have been observed in the reduction of nitrite by bacterial nitrite reductases, which contain iron chlorin or iron isobac-terichlorin [151]. A specific nitric oxide reductase also exists to convert NO to nitrous oxide [9]. Iron complexes of chlorins, isobacteriochlorins, and porphyrins, as well as ruthenium and osmium polypyridines, and cobalt and nickel... 

Manganese porphyrins also form nitrosyl complexes. Fast (ca. 10°M s ) reaction of Mn(II) with NO yields stable MnNO complexes (73) that show a linear Mn—N—0 geometry (74). Interestingly, no reductive nitrosylation is observed for the reaction of Mn(III) with NO (73). Cobalt porphyrins also form stable nitrosyl complexes. The CoNO species obtained, for example, by reaction of NO with Co(Il) porphyrins have been explored as isoelectronic... 

Well-characterized complexes of the MNO 8 class are scarce (Table 7.2).62 Five-coordinate species with bound NO and square pyramidal geometries are dominant,10 18 probably related to the great trans-effect of NO-. Most common are the cobalt nitrosyl porphyrins.18 By reacting with monodentate ligands (NCS-, Cl-, Br-, etc.), six-coordinate complexes may be obtained. Reaction 7.28 describes the preparation of the first compound of this type studied by X-ray methods.13s... 

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