Nitric oxide ligand

Scheldt, W. R., and Elision, M. K., 1999, The synthetic and structural chemistry of heem derivatives with nitric oxide ligands, Acc. Chem. Res. 32 3509359. 

In contrast to the dioxygen, carbon-monoxide, and nitric-oxide ligands, the isocyanide and nitroso functions bear an organic tail. Moreover, nitroso ligands are isoelectronic with dioxygen. 

The substitution of an appropriate number of nitric oxide ligands for carbon monoxide is one possible method of activating metal carbonyl clusters for homo-... 

Martin RL, Taylor D (1976) Bending of linear nitric oxide ligands in four-coordinate transition metal complexes. Crystal and molecular structure of dinitrosyldithioacetylaceto-natocobalt(—I), Co(NO)2. Inorg Chem 15 2970-2976... 

The compound Tr-CsHsNiNO is regarded as formed by a three-electron donation from the nitric oxide ligand. Most NO complexes are best considered as being formed by an initial one-electron transfer to the metal prior to donation from the nitrosonium ion (NO ). The nitric oxide ligand, a so-called odd molecule, is then effectively a three-electron donor. Such a bonding mode is supported by considerable infrared, ESR, and other structural data. It should be noted, however, that recent interpretation of ESR data in terms of MOT indicates that the nitric oxide ligand also can be described by the formal structures NO- and NO , in some complexes. 

The NO ligand can be supplied by nitric oxide itself, but there are many other sources such as nitrite, nitrate or nitric acid, nitrosonium salts or N-methyl-7V-nitrosotoluene-p-sulphonamide (MNTS). The introduction of a nitrosyl group into a ruthenium complex is an ever-present possibility. 

The most important physiological nitrogen substrate of peroxidases is undoubtedly nitric oxide. In 1996, Ishiropoulos et al. [252] suggested that nitric oxide is able to interact with HRP Compounds I and II. Glover et al. [253] measured the rate constants for the reactions of NO with HRP Compounds I and II (Table 22.2) and proposed that these reactions may occur in in vivo inflammatory processes. The interaction of NO with peroxidases may proceed by two ways through the NO one-electron oxidation or the formation of peroxidase NO complexes. One-electron oxidation of nitric oxide will yield nitrosonium cation NO+ [253,254], which is extremely unstable and rapidly hydrolyzed to nitrite. On the other hand, in the presence of high concentrations of nitric oxide and the competitor ligand Cl, the formation of peroxidase NO complexes becomes more favorable. It has been shown [255]... 

SN P spontaneously releases N O both thermally and photochemically [61-65], but is quite stable in the dark and in aqueous in vitro physiological media [66]. This implies that absorption of heat and light energy induces electron transfer from the Fe2+ center to the N 0+ ligand, resulting in weakening of the Fe-N O bond and subsequent release of NO [65]. SNP also decomposes in an aqueous environment in the presence of biological reductants [65, 66] and some transition metal ions to produce nitric oxide. 

In this paper author reported the reactivity of newly synthesized Co(III)-nitrosyls complexes with superoxide radical to follow nitric oxide dioxygenation. Two new Co(III)-nitrosyl complexes bearing N-tetramethylated cyclam (TMC) ligands, [(12-TMC)-Com(NO)]2+ (1) and [(13-TMC)Coin(NO)]2+ (2), were synthesized via [(TMC)Con(CH3CN)]2+ + NO(g) reactions. Spectroscopic and structural characterization showed that these compounds bind the nitrosyl moiety in a bent end-on fashion. Complexes 1 and 2 reacted with K02/2.2.2-ciyptand to produce [(12-TMC)Con(N02)]+ (3) and [(13-TMC)Con(N02)]+ (4), respectively these possess 0,0 -chelated nitrito ligands. 

D. S. Bohle, C. H. Hung, Ligand-Promoted Rapid Nitric Oxide Dissociation from Ferrous Porphyrin Nitrosyls , J. Am. Chem. Soc. 1995,117, 9584-9585. 

Esaki, T., Hayashi, T, Muto, E., Kano, H., Kumar, T.N., Asai, Y., Sumi D., and Iguchi, A., 2000, Expression of nitric oxide synthase and Eas/Fas ligand correlates with the incidence of apoptosis cell death in atheromatous plaques ofhuman coronary arteries, Nitric Oxide 4 561-571. 

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