Complexes Containing Metals Other Than Cobalt

Trivalent metallocorrole complexes containing metals other than cobalt have also been prepared from hydrobromide salts of dideoxybiladienes-ac. For instance, in 1988, Boschi, et al. reported two approaches to the formation of in-plane trivalent rhodium complexes. The first involved reacting octamethylbiladiene-ac 2.106 with... 

The cobalt(III) complexes containing nitrogen as ligating atoms have been studied most extensively. It is hoped that complexes containing metals other than cobalt and ligating atoms other than nitrogen will be investigated in similar detail. 

It is noteworthy that related complexes containing a metal other than cobalt have not been found to be reversible oxygen carriers. 

The existence of copper-nitrosyl complexes of biological significance has been briefly discussed here (Section VII). It is worth pointing out that nitrosyl complexes of other metal-containing proteins may form, and that these may be important in understanding the effects of NO on living cells. Nitrosyl complexes of many other metals are well documented (e.g., Werner and Karrer, 1918 Moeller, 1952) and include complexes of nickel, cobalt, and ruthenium. Some such complexes may be less obvious than the paramagnetic and often colorful... 

Adsorption by carbon, which is one of the oldest adsorption methods used, has been reviewed and evaluated for the preconcentration of trace metals (794). Many authors have discussed the preparation of activated charcoal and carbon from a wide variety of usually local sources. The applications to water treatment are far too numerous to mention other than a few. Jo (795) carbonized a resin and a gum and hydrated the residue above 600 C to produce an adsorbant selective for cadmium(II). Kuzin et al, 196) used deashed active carbon and oxidized carbon for the quantitative sorption of copper, lead, zinc, and nickel from nearly neutral solutions containing 1-2 M alkali-metal halide. Pearson and Siviour (797) converted the metal-ion species to amine complexes before adsorbing these onto carbonaceous materials such as brown charcoal char or cellulose. Mercury vapor can be removed from a solution by reduction followed by passage of a nitrogen stream and adsorption by activated charcoal (798). Activated carbon, which had been oxidized with nitric acid, has been used to extract several metals including divalent nickel, cadmium, cobalt, zinc, manganese, and mercury from fresh water, brine, and seawater (799, 200). 

Whereas for thermal substitution the mechanistic picture is clearer for cobalt(m) complexes than for chromium(m) complexes, for photochemical reactions the reverse is the case. Currently there is much interest, and some success, in bringing the level of understanding of the photochemistry of cobalt(m) and other octahedral complexes up to that of chromium(in) complexes. A recent review of photochemical reactions of transition-metal complexes concentrates on chromium(iii) complexes, but also contains some information on cobalt(ni) and platinum(n) complexes. 

The trinitro-triammine cobalt has practically no conductivity.3 Werner s theory is further supported by the fact that by the introduction of a fourth molecule of ammonia into the triacido-triammine compound the solution becomes once more conducting, as one (N02) group is displaced from the co-ordination complex. The eobalt-ammino-compounds, therefore, containing fewer than three ammino-radicles, contain non-ionisable acidic radicle, and those containing more than three contain ionisable acidic radicles. The generalisation made in connection with the triammino-eompounds led, therefore, to the establishment of the constitution of other ammino-derivatives, and also to the constitution of some of the ammino-salts of divalent and tetravalent metals. 

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. 

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