Thallium kinetic studies

Platinum complexes (continued) with aryls, thallium adducts, 3, 399 with bis(alkynyl), NLO properties, 12, 125 with bisalkynyl copper complexes, 2, 182-186 with bis(3,5-dichloro-2,4,6-trifluorophenyl), 8, 483 and C-F bond activation, 1, 743 in C-H bond alkenylations, 10, 225 in C-H bond electrophilic activation studies, 1, 707 with chromium, 5, 312 with copper, 2, 168 cyclometallated, for OLEDs, 12, 145 in diyne carbometallations, 10, 351-352 in ene-yne metathesis, 11, 273 in enyne skeletal reorganization, 11, 289 heteronuclear Pt isocyanides, 8, 431 inside metallodendrimers, 12, 400 kinetic studies, 1, 531 on metallodendrimer surfaces, 12, 391 mononuclear Pt(II) isocyanides, 8, 428 mononuclear Pt(0) isocyanides, 8, 424 overview, 8, 405-444 d -cP oxidative addition, PHIP, 1, 436 polynuclear Pt isocyanides, 8, 431 polynuclear Pt(0) isocyanides, 8, 425 Pt(I) isocyanides, 8, 425 Pt(IV) isocyanides, 8, 430... 

Miscellaneous kinetic studies of solvolysis in binary aqueous mixtures have included those of the [Co(NH3)5(dmso)] + cation in seventy-one such mixtures, of the /rans-[Co(dmgH)2Cl(N02)] anion and its methylglyoximate analogue in ethanol- and propan-2-ol-water, of [Cr(sal)3] and of ajffy5-tetra-(p-sulphonato-phenyl)porphineiron(m) in ethanol-water, of the 5,6-dimethylbenzimidazoIe derivative of methylcobalamin, of the acid-catalysed hydrolysis of (BHJ- in acetonitrile containing small amounts of water, and of the rate-determining aquation prior to redox of the [Mn(ox)2(OH2)a] anion in aqueous dimethylformamide. A kinetic study of the reaction of thallium(m) with dimethylformamide indicates caution in the use of this co-solvent in binary aqueous mixtures at elevated temperatures or in the presence of oxidants. ... 

In summary, then, the orientation of electrophilic thallation can be controlled by an appropriate manipulation of reaction conditions. Under conditions of kinetic control, ortho substitution results when chelation of the electrophilic reagent (TTFA in the studies described above) with the directing substituent permits intramolecular delivery of the electrophile, and para substitution results when such capabilities are absent this latter result is an expression of the very large steric requirements of the bulky thallium electrophile. Under conditions of thermodynamic control, however, meta substitution is observed. 

As noted earlier, the similarities between H+ and alkali metal cations have led to the use of the former as a probe in biological studies, including studies with various macrocydic ligands, especially those with oxygen donor atoms. The thallium(I) cryptates behave kinetically like the potassium compounds, and the binding constants to 18-crown-6 have been measured by 205T1 NMR methods.347 Several Tl1 compounds with crown ethers (L) have been prepared in... 

Intramolecular electron transfer in a stepwise manner from the amine substrate to die silver(III) center in a 1 2 complex, [Ag(OH)4] -iV,/V-dimcthylanilinc, has been observed.44 The kinetics of oxidation of some aliphatic, heterocyclic, and aromatic aldehydes towards bis(dihydrogentellurato)cuprate(III) and argentate(III) in alkaline medium have been studied.45 A negative salt effect was observed in the oxidation of aminoacetic acid by diperiodatocuprate(III) complex in alkaline medium.46 The oxidation of glutamic acid by thallium(III) perchlorate is catalysed by Ru(M), Os(III), and Nd(III) in a free radical mechanism and the rate is inversely dependent on [H+] concentration.47... 

Ring-opening reactions of cyclopropanes have been observed with a variety of metallic ions. Oullette has studied the kinetics of the reaction of thallium acetate with phenylcyclopropane 56,57) (Eq. (42)). 

Thallium Dorfman and Gryder, investigating the kinetics of the Ce(IV)-Tl(I) reaction, concluded that the mechanism involves two 1-equivalent oxidation steps with a Ce(rV) dimer, with T1(II) as an intermediate. They pointed out that the reaction may be complicated by the formation of OH or NOs free radicals that oxidize TI(I). Sinha and Mathur studied the Ce(IV)-Tl(I) reaction in the presence of the catalysts Ag(I) and Os(VIII). The rate was found to be first order with respect to both Ce(IV) and T1(I) but unaffected by Ce(III) or T1(III). Bisulfate and hydrogen ions acted as inhibitors. The slow step in sulfuric acid medium was considered to be... 

Cyclopropane bonds are susceptible to oxidative cleavage (see Section 2.1.1.2.). Most of the oxidation reactions of activated cyclopropanes involve phenyl-substituted derivatives. When phenylcyclopropane was treated with lead(IV) acetate, 1,3-diacetoxy-l-phenylpropane (63%) and the elimination product cinnamyl acetate (32%) were obtained. The occurrence of traces of l,3-diacetoxy-2-phenylpropane could not be confirmed in later studies. The kinetics of the oxidation of various arylcyclopropanes with lead(IV) acetate, thallium(III) acetate and mercury(II) acetate have been studied. 4-Methoxyphenyl, 4-tolyl, and 4-chlorophenyl derivatives and their meta analogs were treated with these reagents and the rates of reaction and product distributions analyzed. Using lead(IV) acetate, diacetates 1 and cinnamyl acetates 2 were obtained in ratios of about 4 1, whereas thalhum(III) acetate gave the diacetates almost exclusively (see following table). ... 

The most substantial investigation of thallium(II) species in aqueous solution is that of Dodson and Schwarz, who studied equilibria and kinetics of Tl(II)-Cr complexes (77). On the basis of some (reasonable) assumptions, they have calculated the stepwise stability constants K for the three T1C1 " complexes, n = 1,2,3, in 1M HCIO4 and estimated = 1 from the ratios between the stability constants K, for Tfi Cl " and TT C1 ". The absorption spectra of the individual Tl(II) chloride complexes have been derived from their stability constants in combination with the experimental spectra recorded for solutions with varying composition. Absorption maxima were found at 263 and 342 nm for TlCl, at 280 and 342 nm for TICI2, and at 304 and 362 nm for TlCla". An interesting observation was the 10-fold increase of the extinction coefficient (at —340 nm) of the Tl(II) solution in 1 M perchloric acid upon addition of a small amount of chloride ion ([Cl ] = 10 M) (77). 

As discussed in the introduction, during the last decade or two NMR spectroscopy has become the most versatile and powerful technique for studying thallium solution chemistry (39, 40, 54, 161-167). In particular, the potential of this method for studying the aqueous solution chemistry of thallium has been demonstrated in several papers by Glaser et al. (41, 48, 51, 94, 95, 97, 98, 108, 110, 112, 115, 145, 168-174), in which structural, kinetic, and equilibrium problems are studied. In some of these studies, the speciation of the thallium complexes could be elucidated using the individual chemical shifts (and coupling constants) for the studied species 41, 94, 97, 108, 112, 171). 

The kinetic characteristics of ligand exchange of thallium complexes in solution have been little explored, in contrast to the numerous equilibrium studies (4-6,41,57,61,66,67,90,92,93,96,97,112,214-246) and a large number of studies of redox reactions involving thallium (81, 100, 103, no, 246-288). 

The redox properties of thallium are important in preparative organic and organometallic/inorganic chemistry. For this reason, studies of redox behavior and the thermodynamics and kinetics of complexing processes are likely to remain relevant. The employment of the TF ion as a probe for in biological systems will no doubt continue, because of the easy detection of the former. For the same reason, thallium(III) can be used as a representative for several other metal ions in solution. 

Thallium(m) Compounds.—The kinetics of the isotope exchange by electron transfer between Tl and as [Tl(bipy)2] + or [Tl(phen)3] + have been studied using labelled 204xi+. 8o... 

The existence of dimeric and polymeric species in aqueous solutions of indium(m) and thallium(iii) has an effect on kinetics of systems which include these reactants. A T-jump study of indium(iii) perchlorate solution has yielded a value for the rate constant for dimerisation of [InOH] +. Due to ion-pairing complications, it has not proved possible to determine unequivocally, by comparison of rate constants of this and of the indium(m)-sulphate system, whether the rate-determining step in dimerisation of [InOH] + is loss of a solvating water molecule from the indium. The situation is entirely similar for gallium(iii) in perchlorate solution. ... 

The oxidation of the hydrazinium ion by Tl + probably involves substitution of hydrazine for water in the hydrated thallium(iii) species. The kinetics of complex formation between thallium(iii) and 4-(2-pyridylazo)resorcinol in aqueous solutions have been studied. Two pathways have been identified, involving Tl and [T10H] + reacting with the protonated ligand. The similarity in rate to that of the corresponding reaction of thallium(iii) with Semi-xylenol Orange indicates that the rate is controlled by loss of water from the hydrated thallium cation. ... 

CR represent different conformations of the crown ether. T1+ is closer to Ag+ than to K+ or Rb+ in its behaviour. In studies of the aquation of [RhCl,] " by Hg +, Tl +, Cd +, and In + and of the equation of [RhBre] " by Tl + there is a general correlation between the rate and the stability constant of the monohalogeno-complex of the catalytic cation. The decomposition of [MeTl(OAc)2] to TlOAc and MeCOaOMe has been studied in a variety of solvents. Usually simple first-order kinetics are observed, but in deuteuriochloroform and in THE there is an initial induction period in which the solution becomes saturated with TlOAc. The authors propose a rate-determining 5n2 reaction of [AcO] with the methyl group bonded to thallium. 

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