Nitrosyl Derivatives

Amazingly, there is no systematic cis effect of the ligand L trans to carbon monoxide in the carbonylosmium(II) porphyrins Os(OEP)CO(L) [30a-30g], (Table 10). In the nitrosyl derivatives, Os(OEP)NO(L), the anionic ligand Le exerts only a small effect (Table 11) the wavelengths of the a-bands increase in the series [31c] < [3Id] <... 

Craven, P. A., DeRuberts, F. R., and Pratt, D. W. (1979). Electron spin resonance study of the role of NO catalase in the activation of guanylate cyclase by NaN, and NH2OH. Modulation of enzyme responses by heme proteins and their nitrosyl derivatives.). Biol. Chem. 254, 8213-8222. 

Reduction of (V,(V -di oxides (bis nitrosyl derivatives or intramolecular nitroso dimers) with hydrogen with a palladium-on-carbon catalyst [58] (Eq. 54). 

These complexes are generally prepared by methods similar to those employed for the dinitrosyl compounds, treatment of a low-valent molybdenum compound with NO or a nitrosyl derivative being the principal method. Compounds and major physical properties are collected in Table 3. 

Complexes of Other Metals. Having studied in detail catalysts derived from molybdenum nitrosyl complexes, it was interesting to investigate the effect on catalytic activity of substituting other transition metals in both nitrosyl derivatives and in other related complexes. 

In [Fe(NO)(S2CNR2)2] the iron is ligated by four sulfur atoms as well as by the nitrosyl ligand similar Fe(NO)S4 chromophores are found (49) in complexes of dithiolenes (7) and dithiols (8). For both dithiolene and dithiol derivatives, reaction of [FeL2]2 (L = 7 or 8) with NO gas yields the nitrosyl derivatives [Fe(NO)L2] (50), in which the nitrosyl ligand has effected a net oxidation. Certain of the mononegative complexes can be oxidized by iodine to neutral Fe(NO)L2 or reduced with borohydride to dinegative [Fe(NO)L2]2 (50). 

Nitrosyl derivatives of the type [MoCp(NO)(PhN3Ph)]I, prepared from [MoI2Cp(NO)]2 and (PhN3Ph)H, are also known,86... 

There have been several reports of hepatic cholestasis in women taking both troleandomycin and oral contraceptives (361). Oxidation of troleandomycin by CYP3A4 produces a derivative (probably a nitrosylated derivative) that binds tightly to the enzyme and thereby causes inactivation. This inhibition is highly selective for CYP3A4, and hepatic accumulation of ethinylestradiol is possible. 

Carbonyl—nitrosyl derivatives, vanadium compounds, 5, 7 Carbonyl ylides... 

The mass spectra of [C5H5M(CO)2]2 (M = Fe 31> and Ru 33> and of [C5H5Cr(NO)2]2 33) have been investigated. The carbonyl derivatives exhibit only rather routine decarbonylation, dehydrogenation, and acetylene-elimination processes. The nitrosyl derivative [C5H5Cr(NO)2]2 exhibited stepwise loss of nitrosyl groups 33>. 

Key Crystallographic Data for Some Cp2M2(M.-CO)2 (M = Co and Rh) Complexes and Related Nitrosyl Derivatives ... 

C(NH2)2+ unit of arginine, via the formation of hydroxylamine. It can be characterized by ESR spectroscopy using deoxy-myoglobin or -haemoglobin with which it reacts to give nitrosyl derivatives having well-defined spectra. Its chief biological role seems to be as a vasorelaxant (Moncada et al., 1988). 

Various attempts to obtain the carbonyl-pentacyano species [Cr(CN)5(CO)] " have failed (ref. 33, p. 39), but a pentacyano-nitrosyl derivative [Cr(CN)s(NO)] " may be obtained by electrolytic reduction of Kj[Cr(CN)5(N0)] H20 on a mercury cathode, in an alkaline solution containing cyanide ions. The reaction conditions are adjusted to give an approximately O.IOM concentration for the Cr(I) complex, KOH and KCN addition of EtOH to the reduced solution, with rigorous exclusion of air, produces blue-green crystals of K4[Cr(CN)5(NO)] 2 HjO. 

A number of the reactions of nitrous acid, and of nitric acid with more or less extensive contamination by nitrous acid, have been clarified by the recognition that nitrosyl derivatives are involved. Table 9 lists some examples of the intermediates formed with several reactants, together with the concentration terms which appear in the relevant rate equations and some rate coefficients, for the cases in which the nitrous acidium ion is believed to be involved. 

This effect is unusual and, for instance, in the carbonyl and nitrosyl derivatives of chromium, molybdenum, and tungsten there is no shift of the CO or NO stretching bands in the isostructural derivatives with an increasing atomic number. 

Nitrosyl derivatives of the homologues of chromium may be made directly as insoluble precipitates by decomposing the complex anions [CbH5Mo(CO)3] and [CsHsW (CO) 3] with nitric oxide in aqueous media 85). After high-vacuum sublimation at 55-60° the orange-red... 

Inner-Transition Metal to Transition and Inner-Transition Metai Bond 39 9.2.4. Between the Same Metais in Carbonyis and Their Derivatives 9.2.4.13. In Nitrosyl Derivatives... 

Iron-iron bonds exist in carbonyl and nitrosyl derivatives, but these are not considered in this section. Properties consistent with Fe-Fe interactions in other systems are dominated by sulfur donor ligands. The presence of Fe-Fe bonds is not unambiguous, with sulfur bridges invariably accompanying short metal-metal separations. Synthetic routes to polynuclear iron-sulfur complexes are presented for completeness without implying the cluster bonding scheme. 

Carbon monoxide insertion has been observed in nitrosyl derivatives of tung-sten(II) of formula W((t -C5Me5)R2(NO) ... 

The pentamethylcyclopentadienyl analogue of (ri -C5H5)Re(CO)3, (ii -C5Me5)Re (CO)3, has been similarly prepared by the reaction between Re2(CO),o and pen-tamethylcyclopentadienc at 150-210 (eq (8)) [21]. Pentamethylcyclopentadienyl-tricarbonylrhenium(I) thus obtained is converted into a cationic (carbonyl)nitrosyl derivative by treatment with NO Bp4. A hydride reduction of the coordinated carbonyl to methyl has been shown (eq (9)) [21, 22]. 

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