Thallium® complexes

Alkali metal 1-methyl- and 1-phenyl-borinates are also available from bis(borinato)cobalt complexes (see below) on treatment with sodium or potassium cyanide in an aprotic solvent like acetonitrile. Cobalt cyanide precipitates and the alkali borinate remains in solution. After addition of thallium(I) chloride to some complexes, thallium 1-methyl- or 1-phenyl-borinate could be isolated as pale yellow solids, the only main group borinates isolated hitherto. They are insoluble in most organic solvents but readily soluble in pyridine and DMSO. The solids are stable on treatment with water and aqueous potassium hydride, but are decomposed by acids <78JOM(153)265). 

Nickel(III) complexes, with alkyls and aryls, 8, 117 Nickel(IV) complexes, with alkyls and aryls, 8, 117 Nickel coordination complexes, thallium(I) derivatives,... 

A large number of mixed chalcogenides and ternary or more complex thallium-chalcogenide complexes have been prepared and characterized see Chalcogenides Solid-state Chemistry). 

Figure 6 2,6-Trip2C6H3TI complex. Thallium-phenyl core is shown in a ball-and-stick representation peripheral phenyl groups with a tube representation isopropyl groups in wire frame.

Figure 19 Two views of thallium(i) triazapentadienyl complex. Thallium (green), nitrogen (blue), carbon (grey), fluorine (yellow). Hydrogen atoms are omitted for olarity.

The chemical properties span a range similar to the representative elements in the first few rows of the periodic table. Francium and radium are certainly characteristic of alkah and alkaline earth elements. Both Fr and Ra have only one oxidation state in chemical comhina-tions and have little tendency to form complexes. Thallium in the 1+ oxidation state has alkah-like properties, but it does form complexes and has extensive chemistry in its 3+ state. Similarly, lead can have alkaline earth characteristics, hut differs from Ra in forming complexes and having a second, 4+, oxidation state. Bismuth and actinium form 3+ ions in solution and are similar to the lanthanides and heavy (Z > 94) actinides. Thorium also has a relatively simple chemistry, with similarities to zirconium and hafiuum. Protactinium is famous for difficult solution chemistry it tends to hydrolyze and deposit on surfaces unless stabilized (e.g., by > 6 M sulfuric acid). The chemistry of uranium as the uranyl ion is fairly simple, hut... 

Thallium lII) chloride, TlCl3,4H20. Formed by passing CI2 through a suspension of TlCl in water. Hygroscopic, loses CI2 at lOO C. The [TlCl2l ion is stable chloro complexes up to [TlClfi] are formed. 

Thallium occurs in crooksite, lorandite, and hutchinsonite. It is also present in pyrites and is recovered from the roasting of this ore in connection with the production of sulfuric acid. It is also obtained from the smelting of lead and zinc ores. Extraction is somewhat complex and depends on the source of the thallium. Manganese nodules, found on the ocean floor, contain thallium. 

Thallium(III) acetate reacts with alkenes to give 1,2-diol derivatives (see p. 128) while thallium(III) nitrate leads mostly to rearranged carbonyl compounds via organothallium compounds (E.C. Taylor, 1970, 1976 R.J. Ouelette, 1973 W. Rotermund, 1975 R. Criegee, 1979). Very useful reactions in complex syntheses have been those with olefins and ketones (see p. 136) containing conjugated aromatic substituents, e.g. porphyrins (G. W. Kenner, 1973 K.M. Smith, 1975). 

The chelated complex of the benzylamine derivative 505 underwent a remarkable oxidative transformation by treatment with thallium trifluoroace-tate to give narwedine (506) in one step by biomimetic oxidation[459]. 

Selectivity of propylene oxide from propylene has been reported as high as 97% (222). Use of a gas cathode where oxygen is the gas, reduces required voltage and eliminates the formation of hydrogen (223). Addition of carbonate and bicarbonate salts to the electrolyte enhances ceU performance and product selectivity (224). Reference 225 shows that use of alternating current results in reduced current efficiencies, especiaHy as the frequency is increased. Electrochemical epoxidation of propylene is also accompHshed by using anolyte-containing silver—pyridine complexes (226) or thallium acetate complexes (227,228). 

Porphyrin, octaethyl-, thallium chloride complex cyclic voltammetry, 4, 399 <73JA5140)... 

Lithium pyrazolate with complex 235 yields 236 (R = R = H) (97OM2709), while thallium 3-methyl- and 3-fert-butylpyrazolate, 3,5-dimethyl- and... 

Thallium tris(3-mesitylpyrazol-l-yl)borate and [(j -cod)2RhCl] produce [(ry -TpORhfjj -cod)] (93IC3471). These complexes appeared to be good catalysts... 

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