Nitrato cation

Transplutonium(VI) complexes aqua,3,1220 carbonates, 3, 1220 carboxylates chelating, 3, 1220 halogens, 3,1220 monocarboxylates, 3,1220 nitrato, 3,1220 oxides, 3,1220 oxoanions, 3, 1220 Transport cations... 

Garbonato-pentammino-cobaltic Nitr te, [Co(XH3)5(C03)]N03. H20.—Salts of this series were described by Yortmann and Blasberg. 1 They regarded the nitrate, however, as nitrato-pentammino-cobaltic carbonate. Later, Werner and Goslings 2 found that it did not give the reactions of a carbonate, and concluded that the carbonate radicle must be within the complex cation. 

Within each coordination number the oxyanion may function as a monodentate, a bidentate or, very occasionally, a tridentate ligand to an individual metal cation. With the higher anion coordination numbers the M O distances to different metal atoms may not be identical. In practice, coordination numbers of 1 and 2 predominate and are independent of the three main structural types X02, X03 and X04. The coordination number 3 is essentially confined to tetrahedral X04 anions, and the much less numerous coordination numbers of 4-12 also involve mainly tetrahedral X04 type anions, particularly in their anhydrous oxyacid salts M(XO )9 or double salts M M(XO )(f+,. The stoichiometry number, p, is very often a funciton of the oxyanion/metal ratio of the preparative conditions. The higher p, the lower the coordination number of the oxyanion and the more the bonding is likely to involve a monodentate rather than a bidentate function. Nevertheless, the latter is very little influenced by the stoichiometry p. This is illustrated for the bidentate nitrate ion in the six structures (l)-(6),29,31-34 in which p increases from one to six and the bonding role of the nitrato group is essentially unchanged. 

Often nitrato complexes with nitrosonium cations (NO+) M(N03) " are formed. 

The ring-opening reaction is not limited to conventional nucleophiles. Ceric ammonium nitrate in the presence of excess nitrate ion converts oxiranes to / -nitrato alcohols <1995T909>. The reaction is believed to proceed via a one-electron transfer to form an oxiranium radical cation that is subsequently captured by a nitrate ion. Nitric oxide adds to 2,3-epoxy phenyl ketones <2004TL1565>. 

M(N03)4] anions containing the unusual unidentate nitrato ion are also known.Fluoro complexes arc even less prevalent, the preference of these cations being for the other halides, cyanide, N- and heavy atom-donor ligands. 

Anionic nitrato complexes, with mono- or divalent cations as counter-ions, have been known since the last century. These double nitrates have lower solubilities than the simple nitrates previously discussed and they were extensively used until the end of the 1950s for the separation of the individual rare earths (Callow, 1967). 

When the nitrato complex includes an extra cation in the structure, as in the series M2[R(N03)5] nHjO for example, the thermal decomposition scheme becomes more complex. In the case of ammonium compounds the final product, at temperatures well below 1000°C, is R2O3 (or equivalent oxide) but in the case of alkali metals stable double oxides of type MRO2 may be formed. The TG/DTG/DTA patterns for several complex nitrates have been determined by Molodkin and co-workers. 

Unidentate Leaving Groups.— There has been considerable interest in the aquation of the [Co(NH3)sX] + cations. Transition enthalpies (AHiy the difference between the enthalpy of the transition state and the enthalpy of the products) have been estimated for aquation of the [Co(NH3)sX] + cations with X = Cl, Br, I, or NO3. For the chloro-, bromo-, and nitrato-complexes. 

The radical cation fragmentation involves assistance by cerium ammonium nitrate (0.15 mM), the photochemical precursor of the oxidant used in this case, the nitrato radical. 

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