Nitroprusside ion

The coioration is caused by the comersion of acetone by alkali to the CHjCOCHa " ion, which then reactswith the nitroprusside ion [FefCNlsNO]"- giving the highly coloured ion [Fe(CN)sNO-CHiCOCH3] ... 

Nitric oxide coordinated to iron modifies, in a striking manner, the properties and reactivity of free NO (Sec. 6.2). Probably the most famous such coordinated entity is the nitroprusside ion, Fe(CN)5NO . An incisive review of its reactions particularly related to its hypertensive action (it reduces blood pressure of severely hypertensive patients) is available. Nitroprusside ion reacts with a variety of bases... 

Ru(CN)jNO reactions with OH , SH and SOj" resemble those of the nitroprusside ion, with attack at the coordinated nitrosyl to give analogous transients and similar second-order rate constants. Ruthenium(II) complexes of the general type Ru(N2), Nj = biden-tate hgands, are important reactants. The relative inertness of Ru(NH3) + and Ru(diimine)f+ towards substitution makes these complexes definite, although weak, outer-sphere reductants (Tables 5.4, 5.5, 5.6 and 5.1). Ruthenium(ll) complexes of the general type Ru(diimine)f +, and particularly the complex Ru(bpy)j+, have unique excited state properties. They can be used as photosensitizers in the photochemical conversion of solar energy. Scheme 8.1 ... 

The Fe(II)-NO complexes of porphyrins 66-68) and heme proteins 24, 49, 53, 69-76) have been studied in detail by EPR spectroscopy, which allows facile differentiation between five-coordinate heme—NO and six-coordinate heme—NO(L) centers. However, only a few reports of the Mossbauer spectra of such complexes have been published 68, 77-82), and the only Fe(III)-NO species that have been studied by Mossbauer spectroscopy include the isoelectronic nitroprusside ion, [FeCCNlsCNO)] (7S), the five-coordinate complexes [TPPFe(NO)]+ 68) and [OEPFe(NO)]+ 82), and two reports of the nitro, nitrosyl complexes of iron(III) tetraphenylporphjrrins, where the ligand L is NO2 82, 83). 

Nitric oxide has recently been found to be important messenger molecule mediating critical physiological functions such as neurotransmission and muscle relaxation. The nitroprusside ion, which is clinically used as a vasodilator, functions by releasing NO in vivo. The reactivities of these molecules are surveyed with a view toward the development of metallonitrosyls as pharmaceutical... 

General Properties of the Nitroprusside ion, [Fe(CN)5NO]2 (NP), and Related Nitrosyl Complexes... 

Even small amounts of alkali convert the nitroprusside ion to pentacyanonitroferrate (II) which, in turn, is changed to ferrocyanide by the action of cyanide. 

It has been known for a long time that nitrosyl complexes can be prepared using nitric acid the nitroprusside ion [Fe(CN)5NO]2 was first obtained by its action on [Fe(CN)6]3-.85 In many cases the production of such species was accidental and the reactions are often quite complex. Several nitrosyls of the platinum metals have been obtained in this way and recently the polymeric species Pt4(MeC02)6(N0)2 was isolated, together with other products, from the reduction of PtIV in a mixture of nitric and acetic acids.57... 

Reactions have been known to occur at the nitrosyl group in the nitroprusside ion, [Fe(CN)3-NO]2-,8 for some considerable time recently similar behaviour has been observed in other systems. Different types of reactivity are exhibited depending on the nature of the nitrosyl complex and the mode of coordination of the NO ligand. For general reviews of this topic see references 9, 11 and 14. 

Protonation of a reduced form of nitroprusside ion gives a stable blue solid apparently attack also occurs at the O atom here (equation 27).102... 

The nitroprusside ion is attacked by hydroxide to yield the corresponding nitro compound [Fe(CN) N02]4 . The rate of formation of [Fe(CN)5N02]4 is first order in OH- and nitroprusside concentrations118 and electrochemical studies suggest119 the formation of the transient intermediate [Fe(CN)s(N(=0)0H)]3 (equations 12 and 13). 

NH3 to give [Fe(CN)5CO]3-). [Fe(CN)5NH3]3 is best prepared285 from the nitroprusside ion by standing in a solution of concentrated ammonia buffered with sodium acetate as in equation (34). 

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