Inverted Ligand Field in a Pentanuclear Bow Tie Au/Fe Carbonyl Cluster

Gold chemistry has experienced in the last decades exponential attention for a wide spectrum of chemical applications, but the +3 oxidation state, traditionally assigned to gold, remains somewhat questionable. Herein, we present a detailed analysis of the electronic structure of the pentanuclear bow tie Au/Fe carbonyl cluster [Au{η2-Fe2(CO)8}2]- together with its two one-electron reversible reductions. A new interpretation of the bonding pattern is provided with the help of inverted ligand field theory. The classical view of a central gold(III) interacting with two [Fe2(CO)8]2- units is replaced by Au(I), with a d10 gold configuration, with two interacting [Fe2(CO)8]- fragments. A d10 configuration for the gold center in the compound [Au{η2-Fe2(CO)8}2]- is confirmed by the LUMO orbital composition, which is mainly localized on the iron carbonyl fragments rather than on a d gold orbital, as expected for a d8 configuration. Upon one-electron stepwise reduction, the spectroelectrochemical measurements show a progressive red shift in the carbonyl stretching, in agreement with the increased population of the LUMO centered on the iron units. Such a trend is also confirmed by the X-ray structure of the direduced compound [Au{η1-Fe2(CO)8}{η2-Fe2(CO)6(μ-CO)2}]3-, featuring the cleavage of one Au-Fe bond

Electron transfer and CO addition to polynitrido cobalt carbonyl clusters: Parallel pathways for conversion of the [Co10N2(CO)(19)](4-) anion to the novel [Co11N2(CO)(21)](3-) anion

The redox aptitude of the dinitrido anion [Co10N2(CO)19]4- has been tested from both chemical and electrochemical points of view, together with its reactivity toward CO that induces disproportionation. In any case, through a remarkable overlapping of intermediate steps, the new anion [Co11N2(CO)21]3- (4) is eventually obtained. A detailed study of the pathways to 4 allowed the identification of three labile intermediates by their characteristic IR spectra as well as their electrochemical and paramagnetic properties. The unprecedented structure of trianion 4 has been studied in details in two different crystalline salts

Endohedral Metallofullerenes Today: More and More Versatile Ships in Multiform Bottles-Electrochemistry of X-Ray Characterized MonometallofullerenesAdvances in Organometallic Chemistry and Catalysis

Endohedral Metallofullerenes Today: More and More Versatile Ships in Multiform Bottles—Electrochemistry of X-Ray Characterized Monometallofullerene

The competition between chemistry and biology in assembling iron-sulfur derivatives. Molecular structures and electrochemistry. Part IV. [Fe3S4](SγCys)3 proteins

Iron-sulfur clusters are ubiquitous and evolutionary ancient prosthetic groups which participate in electron transfer processes of crucial biological interest. In view of such a significant aspect we aimed to update their structure and electrochemistry. In this picture, after having reviewed Fe(SγCys)4 rubredoxins (Coord. Chem. Rev., 257 (2013) 1777–1805), [Fe2S2](SγCys)4 ferredoxins (Coord. Chem. Rev., 280 (2016) 50–83) and Rieske [Fe2S2](SγCys)2(His)2 ferredoxins (Coord. Chem. Rev., 306 (2016) 420–442), we will now deal with [3Fe-4S] proteins. As usual, we will also deal with the synthetic analogues of the related iron-sulfur clusters

Mononuclear Metallacarboranes of Groups 6-10 Metals. Analogues of Metallocenes: Electrochemical and X-Ray Structural Aspects

Metallacarboranes containing carborane ligands possessing a pentagonal open face can coordinate metal atoms in a η5-manner quite similar to the cyclopentadienyl monoanion, thus affording metallocene analogues. By virtue of such an analogy, their electron transfer aptitude plays an important role in their physico-chemical characterisation. We review such an aspect, also providing evidence for the structural consequences of their electron transfer processes. At variance with metallocenes, electrochemical investigations on the metallacarboranes have not yet become a routine tool to search for their potential application in fields which require electronic mobility

Redox Chemistry and Electrochemistry of Homoleptic Metal PhenolatesPATAI'S Chemistry of Functional Groups

The redox chemistry of aryl alcohols, or phenols, is of great interest because of their involvement in important biological and industrial processes. Phenol and its substituted analogs are facile one-electron reducing agents that are often involved in electrochemical, photochemical and radiation chemical electron transfer reactions. For these and many other reasons the interest of chemists in the metal phenolates has always been lively and a huge number of these complexes are known. In this chapter we describe the redox behavior of the more restricted set of homoleptic aryloxide complexes. The peculiarities of phenolates as ligands make them usually unable to stabilize a metal in different redox states and, very often, reduction of the metal is accompanied by the release of one or more of the ligands and/or by the formation of polynuclear compounds. This may give rise to a complicated pattern in the redox chemistry of these complexes, but may also open the way to a rich, redox-driven, chemistry of this class of compounds, which, apparently, is still largely unexplored

Density functional description of the bonding in the m3-chalcogenido hexanuclear octahedral clusters [Co6(m3-X)8(Pet3)6 ] (X=S, Se, Te)

Density functional theory (DFT) in the local density approximation has been applied to describe the bonding in the μ3-chalcogenido hexanuclear cobalt clusters of formula [Co6(μ3-X)8(PR3)6] (X = S, Se, Te). The geometries of the clusters have been optimised and the bonding interactions in the sulfide derivative have been analysed using a fragment decomposition scheme. Direct metal-metal interactions are negligible. The electrochemical behaviour reported for the sulfide cluster has been rationalised