Tetraphenylporphyrin dianion

The rate of Sc -promoted photoinduced electron transfer from Ceo to CI4Q determined from the decay rate of the absorbance due to Ceo at 740 nm (inset of Fig. 11) obeys pseudo-first-order kinetics and the pseudo-first-order rate constant increases linearly with increasing the p-chloranil concentration [CI4Q] [135]. From the slope of the linear correlation, the second-order rate constant of electron transfer ( et) in Scheme 15 was obtained. The A et value increases linearly with increasing the Sc + concentration. This indicates that CUQ produced in the photoinduced electron transfer forms a 1 1 complex with Sc + (Scheme 15) [78]. When CI4Q is replaced by p-benzoquinone (Q), the value for electron transfer from Ceo to Q increases with an increase in [Sc " ] to exhibit a first-order dependence on [Sc ] at low concentrations, changing to a second-order dependence at high concentrations, as shown in Fig. 13 (open circles) [135]. Such a mixture of first-order and second-order dependence on [Sc ] was also observed in electron transfer from CoTPP (TPP = tetraphenylporphyrin dianion) to Q... 

DiEtMeBPheod 4,5-diethyl methylbacteriopheophorbide d mesoporphyrin IX dimethyl ester Methyl Pheophorbide a Ethyl Chlorophyllide a or b Methyl Chlorophyllide a Methyl Pyrochlorophyllide a 3-vinyl-8-(E-2-nitrovinyl-l)deutero monoanion of 21-Methyl-5,10,15,20-tetraphenylporphyrin monoanion of 21-Phenyl-5,10,15,20-tetraphenylporphyrin dianion of 5,15-dimethyl-2,3,7,8,12,13,17,18-octaethylporphyrin... 

A range of neutral, singly and doubly oxidized heteroleptic double-decker complexes of the type [M(IV)(P)(Pc)](n), where n = 0, +1, or +2, M=Zr or Hf, P = the dianion of octaethylporphyrin (OEP) or tetraphenylporphyrin (TPP), and Pc = the dianion of phthalocyanine, has been reported. Each oxidized or reduced compound was characterized by UV-visible and/or EPR spectroscopy. The neutral compounds all undergo two reversible ring-centered oxidations and two reversible ring-centered reductions. The redox potentials were found to depend upon the type of macrocycle. They also vary with the size of metal ion in the case of oxidation but not in reduction, where E° values are relatively unaffected and shift by only 20-40 mV upon going from Hf(P)(Pc) to Th(P)(Pc), as compared to a much larger 220-280 mV shift between E° for the first oxidation of the same compounds [27]. 

Temperature not reported. 1 Rjdt — 4-morpholinodithiocarboiylate. 11TPP = dianion of meso-tetraphenylporphyrin. 

Complexes of the type [Rh(TPP)(RX)] [RX = C H X (n = 3-5, X = Cl or Br n = 3-6, X = I) TPP = dianion of tetraphenylporphyrin] were prepared by Anderson et al. (179). The nature of RX was found to determine the overall electrochemical behavior for the reduction of [Rh(TTP)(RX)]. For some complexes, specifically those where X = Br and I, the bound alkyl halide could be reduced without cleavage of the metal-carbon bond. This resulted in the electrochemically initiated conversion of [Rh(TPP)(RX)] to a [Rh(TPP)(R)] complex. The E. value for this reduction was dependent on the chain length and halide of the RX group and followed the trend predicted for alkyl halides. The reduction of the bound RX occured at Ei values significantly less negative that those for reduction of free RX under the same solution conditions. 

Metal ions (e.g., Mg +) were reported to promote ET from (TPP)Co (Tpp2- dianion of tetraphenylporphyrin) to /)-benzoquinone (Q), although no... 

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