Metalloporphyrins with metal-metal bonds. Synthesis and characterization of (P)InMn(CO)5, (P)InCo(CO)4, and (P)InM(CO)3Cp where M = Cr, Mo, and W. Molecular stereochemistry of [(2,3,7,8,12,13,17,18-octaethylporphyrinato)indium(III)]pentacarbonylmanganese

Abstract

259ChemInform Abstract The title complexes (III) can be prepared using slightly different methods. On the basis of 1H NMR, IR, and electronic spectroscopy data, the presence of a single metal-metal covalent bond is suggested. This assumption is confirmed by an X-ray diffraction study of (IIIa) (space group P1, Z=2). The electrochemical behavior of (III) is investigated by cyclic voltammetry using the examples of (IIIa)-(IIIc), and (IIIe). In all cases the addition or abstraction of one electron to or from the bimetallic compound leads to a porphyrin anion or cation whose lifetime is short and varies with the axial ligand. Electroreduction seems to involve the porphyrin π ring system but participation of a σ metal-based orbital cannot be ruled out. In contrast to the octaethylporphyrinato complexes the tetraphenylporphyrinato derivatives are reduced in two one-electron transfer steps.

Photocatalytic oxidation of organic compounds by polyoxometalates of molybdenum and tungsten. Catalyst regeneration by dioxygen

“…Me2CHOH, or other organic compounds, undergoes a series of photoreactions that result in stepwise reduction of the polyoxometalate and oxidation of the alcohol. 8 The overall mechanism, for the first two reduction steps, may be presented as follows:…”

“…We present as follows the various reactions in which dioxygen participates as an oxidizing reagent, with the corresponding redox potentials:12 02 + e" H+ -H02 E = -0.05 V (NHE) (7) Oz + e" -Of E = -0.33 V (NHE) (8) 02 + 2H+ + 2e" -H202 E -0.695 V (NHE)…”

FT-EPR Study of Methyl Radicals Photogenerated from [Ru(Me)(SnPh3)(CO)2(iPr-DAB)] and [Pt(Me)4(iPr-DAB)]: An Example of a Strong Excitation Wavelength Dependent CIDEP Effect

“…Many studies have been made of the photochemical alkyl radical formation from transition metal − and main group metal − compounds with alkyl ligands. Alkyl radicals can be used as addition polymerization initiators or reagents in organic synthesis .…”

Metalloradical Chemistry of Cobalt(II) Porphyrins. The Syntheses, Structure, and Reactivity of Triphenyltin(II)- and Trihalomethylcobalt(III) Octaethylporphyrin

“…One-electron oxidation of the metal−metal σ-bonding HOMO decreases the formal bond order from 1 to 0.5. In an analogous situation, the decrease in bond order upon one-electron reduction of Co−C bonded complexes results in a >10 15 acceleration of the homolysis rate. − The cyclic voltammograms of several bimetallic indium porphyrin complexes (P)InM(L) exhibit oxidative instability like that of Co III (OEP)SnPh 3 . The enhanced current of the first, totally irreversible oxidation processes in these systems was attributed to oxidation at the same potential of some of the M(L) • radical generated by rapid cleavage of the metal−metal bond.…”

“…[50][51][52] The cyclic voltammograms of several bimetallic indium porphyrin complexes (P)InM(L) exhibit oxidative instability like that of Co III -(OEP)SnPh 3 . 53 The enhanced current of the first, totally irreversible oxidation processes in these systems was attributed to oxidation at the same potential of some of the M(L) • radical generated by rapid cleavage of the metal-metal bond. In contast to the bond cleavage observed here, oxidation of alkyland aryl-Fe(III) and Co(III) porphyrin complexes results in intramolecular migration of the alkyl or aryl group from the metal to nitrogen to afford an N-substituted porphyrin complex.…”