112022-38-5Relevant articles and documents
Metalloporphyrins with metal-metal bonds. Synthesis, characterization, and electrochemistry of (P)TlMn(CO)5, (P)TlCo(CO)4, and (P)TlM(CO)3Cp where M = Cr, Mo, and W. Crystal structure of [(2,3,7,8,12,13,17,18-octaethylporphinato)thallium(III)]pentacarbonylmanganese
Guilard,Zrineh,Ferhat,Tabard,Mitaine,Swistak,Richard,Lecomte,Kadish
, p. 697 - 705 (2008/10/08)
The synthesis, physicochemical properties, and electrochemistry of a new series of metal-metal σ-bonded thallium porphyrins are reported. The metalate ligands σ-bonded to the thallium octaethyl- or tetraphenylporphyrin complexes were Mn(CO)5, Co(CO)4, W(CO)3Cp, Mo(CO)3Cp, and Cr(CO)3Cp. Each neutral complex was characterized by 1H NMR, IR, and UV-visible spectroscopy, all of which suggested a single metal-metal covalent bond. The crystal structure of (OEP)TlMn(CO)5 was also solved (triclinic, P1, a = 12.467 (2) A?, b = 13.528 (2) A?, c = 15.088 (3) A?, α = 62.04 (2)°, β = 61.62 (2)°, γ = 69.53 (2)°, Z = 2, R(F) = 0.027, Rw(F) = 0.033, w = (σ2(I) + 0.04I)-1). The σ Tl-Mn bond length is 2.649 (1) A?. Electrochemistry and spectroelectrochemistry techniques were used to characterize each oxidized and reduced complex in methylene chloride containing 0.1 M tetrabutylammonium hexafluorophosphate as supporting electrolyte. Each complex underwent two oxidations, which were centered at the porphyrin π ring system. Unlike the case for metal-metal-σ-bonded indium porphyrins, no cleavage of the σ-bond occurs following the first oxidation; i.e., the generated radical cations are stable on the cyclic voltammetry time scale. The metal-metal-bonded compounds could also be reduced by two one-electron additions, but the generated anion radical stability was very low. The ultimate products of electroreduction were the free base porphyrin radical anion and a bis(thallium(I)) compound that was formed from a transient mono(thallium(I)) porphyrin complex.
