Thallium porphyrins

Aluminum, Gallium, Indium, and Thallium Porphyrin Complexes, M(Por)R... 

The thallium complexes show somewhat different electrochemical behavior, and reversible oxidations are observed for both n-alkyl and n-aryl thallium porphyrins, indicating that the oxidized complexes have a more stable metal—carbon bond than the gallium or indium analogs. Spectroelectrochemistry revealed that the first oxidation is porphyrin ring-centered. The first reduction is reversible and ring... 

Overall, the UV-visible, NMR, and electrochemical data for the range of O -bonded complexes of gallium, indium, and thallium porphyrins show that there is a trend from pure a -bonded character of the M—C bond in the alkyl complexes to the much more ionic character observed for the fluorophenyl and acetylide complexes. These more ionic complexes show NMR and UV-visible characteristics more like those of the ionic M(Por)Cl or M(Por)C104 complexes. ... 

Most of the studies on organo-gallium, indium, and thallium porphyrin complexes have focused on synthesis and properties of the complexes, and rather little attention has been devoted to reaction chemistry. Two areas which have received some attention are the insertion of small molecules (SO2 or CO2) into the metal—carbon bonds and photochemical metal—carbon bond cleavage. The... 

Halide complexes of this group react with carbanions to form stable alkylmetalloporphyrins.27 The thallium atom is significantly displaced (0.98 A) from the N4 plane with a large T1—N,, distance (2.29 A) in Tl(TPP)Me, formed by the reaction of H2TPP and MeTl(OCOMe)2 (Scheme 5). Monovalent thallium porphyrin complexes are also known.17 They can be prepared by treating a porphyrin with thallium(I) ethoxide in THF.29 Unlike the other Group IIIB metalloporphyrins, [Tl i Por) is easily hydrolyzed. 

The electrochemistry of gallium, indium, and thallium porphyrins with o-bonded aryl and alkyl groups has been reported by Kadish and Guilard . Complexes of Ga(Por)(R), In(Por)(R) and Tl(Por)(R) are reversibly reduced by up to two single electron transfer additions. These electroreductions are shown in Eq. 12 and 13 where M = Ga, In, or Tl. 

Substrate resonances may also be affected by complexation to diamagnetic complexes, where the complexes possess ligands having a diamagnetic anisotropy [38]. Such compounds, e.g. chlorophyll or Ru" porphin show such effects. Here too the mutual interactions of the complexes themselves should be taken into account [39]. The thallium porphyrins cannot further complex and the aggregates are assumed to be formed from an electrostatic interaction between the porphyrin rings. 

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). 

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

The porphyrin derivative of thallium(III) has been found437 to have the metal atom above the N4 plane by 0.9 A. Electrochemical two-electron reduction results in reduction to Tl L-(L = porphyrin), and subsequent protonation gives H2L and Tl+ in aqueous solution.438... 

Oxophlorin formation can be carried out very much more efficiently by treatment of zinc(II) or magnesium(II) porphyrins (41) with thallium(III) trifluoroacetate an intermediate... 

Thallium complexes amidines, 205 phthalocyanines, 863 porphyrins, 821 triazines, 205 Thallium(I) complexes... 

Thalliuin(III) trifluoroacetate will also eliminate trifluoroacetic acid in reactions with compounds containing N—H bonds 40, 240). Thus, brief treatment of octaethylporphyrin in CHgCla and tetrahydrofuran with an excess of T1(02CCF3)3 followed by chromatography on deactivated alumina affords the complex shown in Fig. 10, This was the first unambiguous characterization of a thallium(III) porphyrin 240). 

Heterometallic homo- and heteroleptic porphyrinate dimers with metal-thallium bonds have been described. These include (OEP)Rh Tl(OEP), (TPP)Rh Tl(OEP), (OEP)Rh-Tl(TPP), and (TPP)Rh-Tl(TPP). The ETV-visible spectroscopy confirms the presence of a strong tt-tt interaction between the macrocycles in each metal derivative. 

I a porphyrins are salts with two M+ counterions II a and II b porphyrins contain metals in their +2 oxidation states Illb porphyrins in the +3 state. All complexes are diamagnetic and produce normal electronic spectra. Most of them fluoresce. For thallium a labile green TPP complex has been described (696, 646, 483, 458), which could be the TI21 salt [.Rothemund (153)]. A report on Tl11 porphyrins (153) is probably in error, because in air only Tlni porphyrins have been found in later investiga-... 

The thallium (III) complex [T1 (OETNP)Cl)] also crystallised with two crystallographically independent molecules. Surprisingly, the structure shows a much smaller degree of conformational distortion than observed in Ni(OETNP), H2(OETNP) and other dodecasubstituted porphyrins (Fig. 21). While in the strongly distorted structures displacement of the Cp atoms are in the range 0.9 A-1.2 A, the two thallium derivatives show displacements of 0.3 and 0.17 A... 

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