Cobalt , nitrato complexes

This report also describes two new examples of nitrato-metallate coordination compounds which involve a phosphorus-containing ligand. One is the complex [AgL2N03] and the other the blue diamagnetic cobalt(I) complex anion [CoL(N03)2] Of the more than 100 compounds reported in the literature, which are suspected to contain coordinated nitrate, the 12 examined by x-ray diffraction technics are listed in Table II. Two reviews on metal-nitrate interactions have appeared recently (3, 19), so only some general observations will be made here. 

Dr. Pearson presented data on the optical density observed when the nitrato-cobaltic complex reacts with thiocyanate ion, and there is nothing to object to in these results. But I think one might be concerned about the theoretical curve calculated using the competition ratio in a table wrhich Haim and Taube presented in the journal. 

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. 

On the basis of these observations and conclusions it was suggested that the cobalt complexes described above might follow a related pathway. Here, however, it can be argued that the presence of base in, e.g. the reactions of Co(dmgH)2NO, leads initially to the quantitative formation of Co,(dmgH)2(NO)B. In this case attack of 02 leads first to the peroxy compounds and then, because of the absence of a suitable NO+ compound, rearrangement occurs to give the nitrito derivative. Clearly whether or not nitro or nitrato compounds are produced would depend on the concentration of base B. In some cases it is possible to obtain mixtures of such products. These oxidations are also observed for other metals, e.g. equations (37) and (38). 

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