Nitrido structure

The most important members of this class are the osmium nitrido, and the osmyl complexes. The reddish-purple K2[OsNCl5] mentioned above is the result of reducing the osmiamate. The anion has a distorted octahedral structure with a formal triple bond Os=N (161pm) and a pronounced /ram-influence (pp. 1163-4), i.e. the Os-Cl distance trans to Os-N is much longer than the Os-Cl distances cis to Os-N (261 and 236 pm respectively). The anion [OsNCls] also shows a rram-effect in that the Cl opposite the N is more labile than the others, leading, for instance, to the formation of [Os NCl4] , which has a square-pyramidal structure with the N occupying the apical position. 

Figure 1.75 The structure of the dimeric nitrido complex [Ru2NC18(H20)2]3. ...

Iron centers that are more electron-deficient than iron(III) compounds are used for efficient and highly specific oxidation reactions in, for example, heme and nonheme enzymes [166-172]. Most iron(IV)-complexes found in biological reaction cycles possess terminal or bridging 0x0 groups as is known from a large number of structural and spectroscopic investigations. With the exception of iron(IV)-nitrido groups, nonoxo iron(IV) centers very rarely take part in such reactions. 

The structure of the bpy and phen complexes is also most probably pentagonal bipyramidal with the nitrido ligand in an axial position and the heterocyclic ligand spanning axial and equatorial positions [178]. In the IR spectra of the nitridoperoxo complexes v(TcN) occurs at 1069-1035, v(O-O) at 912-894 and vSym(Tc02) at 665-647 cm-1 [177]. 

Some recent interest in the technetium chemistry has been focused on complexes possessing a Tc=N3+ core. Tetrachloronitridotechnetate(VI) complexes can easily be synthesized by the reaction of pertechnetate with sodium azide in concentrated hydrochloric acid [34], Although its square-pyramidal structure resembles that of tetrachlorooxotechnetate(V) complexes, stable character of the nitrido complexes in aqueous solution shows a remarkable contrast to the oxo complexes. However, when a strong acid and a coordinating ligand are absent, the interconversion of di(p-oxo)nitridotechnetium(VI) complexes to the monomeric form occurs in the following complicated manner [35]... 

C. Electronic Structure and Reactivity of Molybdenum Nitrido and Imido Complexes... 

Structural studies of the nitrido complexes are listed in Table 1. 

Table 1 Crystal structure determinations of the nitrido Schiff base Mn complexes. Ligand substituents are...

In aqueous solution, the reactivity of (34) is unique and does not have parallels among other transition-element nitrido complexes. For instance, a characteristic feature is the formation of [NTc(/r-0)TcN] + or [NTc(/u-0)2TcN] " structural units by hydrolysis (see Scheme 13). As observed with many high-valent M=0 species, substitution of halides by water leads to highly... 

---