Electrochemical oxidation of π-C5H5M(CO)3 (M = Mn, Re) and their derivatives

Cymantrene Radical Cation Family: Spectral and Structural Characterization of the Half-Sandwich Analogues of Ferrocenium Ion

“…In terms of the literature background for this study, the anodic electrochemistry of cymantrene and its methylcyclopentadienyl analogue Mn(η 5 -C 5 H 4 Me)(CO) 3 have been the subject of a number of papers which are in agreement that the oxidation is a one-electron process. – , Depending on the medium, the radical cations may be sufficiently stable on a CV time scale that the 0/+ couple is at least partially chemically reversible, especially at reduced temperatures, a fact that allowed for the study of carbonyl substitution reactions by cyclic voltammetry . Spectral characterization of the radical cations was blocked, however, either by electrode passivation effects or by decomposition on an electrolysis time scale. , Optical and ESR studies of this family of radicals has required substitution of one or more of the carbonyls by donor ligands, which has the effect of greatly enhancing the lifetimes of the radical cations. – ,– …”

“…The expectation that cymantrene would be significantly harder to oxidize than ferrocene owing to the presence of its strongly π-accepting carbonyl groups has been confirmed both by photoelectron spectroscopy (PES) , and by a number of electrochemical studies. – More poorly understood, however, is the dramatically reduced lifetime of the cymantrene radical cation, 1 + , compared to the ferrocenium ion. The frontier orbitals of cymantrene and ferrocene are similar in makeup, both compounds being viewed as pseudo-octahedral systems in which the three fac carbonyls are topologically equivalent to the Cp anion, , with the three highest-energy filled orbitals for the d 6 complexes being closely spaced in energy.…”

Combining organometallic and Werner-type coordination sites in highly preorganized heterobimetallic systems

“…3) [19], which we assign to the formation of the Mnll (d5) species. No further redox processes are de tectable in the potential range -1.6 to + 1.6 V. Oxida tion potentia Is of CpMn(COhL complexes are known to vary over a potential range of more than 2 V, depending of the nature of the ligand L [20][21][22][23]. The rather low oxidation potential of 4 indicates significant stabilization of the Mnll state by the anionic pyrazolate ligand and refl ects the high nucleophilicity of the N-het erocycle [22].…”

Electrochemistry Inside Microdroplets of Kerosene: Electroanalysis of (Methylcyclopentadienyl) Manganese(I) Tricarbonyl(I)

“…Denisovich et al first reported the cyclopentadienyl manganese(I) tricarbonyl oxidation via a one electron step at a platinum microelectrode in acetonitrile supported with tetrabutylammonium perchlorate [13]. In the same report the authors compared the much more positive potential (E 1/2 ¼ þ 1.22 V (vs. SCE)) applied for the manganese halfsandwich complex oxidation than ferrocene (E 1/2 ¼ þ 0.01 V) in the same conditions [13].…”

“…In the same report the authors compared the much more positive potential (E 1/2 ¼ þ 1.22 V (vs. SCE)) applied for the manganese halfsandwich complex oxidation than ferrocene (E 1/2 ¼ þ 0.01 V) in the same conditions [13]. Despite most manganese half-sandwich complexes undergoing an electrochemically reversible oxidation [13], the (methylcyclopentadienyl) manganese(I) tricarbonyl oxidation in acetonitrile is only electrochemically reversible at low temperatures (ca. À 28 8C below) at a platinum electrode [14].…”