NO ligand

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 NO ligand is usually regarded as a good a-donor and, therefore, electrophilic, so that the above reaction can be reversed by nucleophilic attack... 

No ligands of IP3R have yet found clinical application. Most agonists of IP3R are either modifications of DP3 or derived from adenophostin A. The only known antagonists of IP3R (e.g., heparin, 2-AJPB) are vety poorly selective. 

Heterodinuclear Ni-Fe complexes, which are not stabilized by the phosphine and NO ligands, were synthesized by Tatsumi and coworkers as [NiFe] hydrogenase mimics [208-210]. Several examples are shown in Fig. 8. However, the catalytic activities of these complexes are not ascertained. 

In recent years, several model complexes have been synthesized and studied to understand the properties of these complexes, for example, the influence of S- or N-ligands or NO-releasing abilities [119]. It is not always easy to determine the electronic character of the NO-ligands in nitrosyliron complexes thus, forms of NO [120], neutral NO, or NO [121] have been postulated depending on each complex. Similarly, it is difficult to determine the oxidation state of Fe therefore, these complexes are categorized in the Enemark-Feltham notation [122], where the number of rf-electrons of Fe is indicated. In studies on the nitrosylation pathway of thiolate complexes, Liaw et al. could show that the nitrosylation of complexes [Fe(SR)4] (R = Ph, Et) led to the formation of air- and light-sensitive mono-nitrosyl complexes [Fe(NO)(SR)3] in which tetrathiolate iron(+3) complexes were reduced to Fe(+2) under formation of (SR)2. Further nitrosylation by NO yields the dinitrosyl complexes [(SR)2Fe(NO)2], while nitrosylation by NO forms the neutral complex [Fe(NO)2(SR)2] and subsequently Roussin s red ester [Fe2(p-SR)2(NO)4] under reductive elimination forming (SR)2. Thus, nitrosylation of biomimetic oxidized- and reduced-form rubredoxin was mimicked [121]. Lip-pard et al. showed that dinuclear Fe-clusters are susceptible to disassembly in the presence of NO [123]. 

He compared the infrared spectra of cements with that of zinc polyacrylate salt and found differences. Inspection of his data shows that, unlike the cements, the salt was purely ionic, so that it seems here that cement formation is associated with the formation of coordination complexes. There are no ligand field stabilization effects with the Zn ion because it has a completed d shell (Cotton Wilkinson, 1966). For this reason the... 

No ligand EphB2 receptor N-terminal globular domain - —... 

M-X-Y atoms, are collinear. For two angularly bound NO ligands, the actual 0n M-n angle, obviously, cannot be estimated using Eqn. 1 as sometimes assumed. 

The areas I and II in Figure 2.9 correspond to oxidation of NO ligand and shrinking (I) or minute elongation (II) of the intemuclear distance. There are only two cations... 

Figure 2.9. Correlation between change of the N—O bond length (AdN—0) and the partial charge (2no) accumulated on the NO ligand upon interaction with TMI encaged in ZSM-5.

Figure 2.12. BP/DNP calculated spin density contour of the r/-/V 2CuNO nM5 complex and for the NO molecule, showing two possible routes of NO attachment an inner-sphere attack at the metal center (slim arrow) and an outer-sphere attack at the NO ligand (bold arrow) (after [75]).

Figure 2.21. Changes in (a) total energy and (b) partial charge on the terminal oxygen atoms of the NO ligands, calculated for the stepwise decrease of the 0—0 distance in the attracto conformation of the copper(I) dinitrosyl complex (after [75]).

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