Molecular Fe, CO and Ni carbide carbonyl clusters and Nanoclusters†

The present minireview highlights the work of our group on Fe, Co and Ni carbide carbonyl clusters and nanoclusters, placing it in the context of the recent literature. After a brief introduction, Section 2 gives a short summary on the general features of molecular carbide carbonyl clusters. Then, specific examples of Fe, Co and Ni carbide carbonyl clusters are presented in the following three Sections. Each Section includes both homometallic and heterometallic clusters, as well as discussion of some of their most relevant chemical, electrochemical, structural and physical properties. General conclusions are outlined in Section 6

Alternative synthetic route for the heterometallic CO-releasing [Sb@Rh12(CO)27]3− icosahedral carbonyl cluster and synthesis of its new unsaturated [Sb@Rh12(CO)24]4− and dimeric [{Sb@Rh12Sb(CO)25}2Rh(CO)2PPh3]7− derivatives

Abstract The hetero-metallic [Sb@Rh12(CO)27]3− cluster has been known as for over three decades thanks to Vidal and co-workers, and represents the first example of an E-centered (E=heteroatom) icosahedral rhodium carbonyl cluster. However, its synthesis required high temperature (140–160 °C) and elevated CO pressure (400 atm). Applying the redox condensation method for cluster preparation, we herein report a new synthetic, high-yield route for preparing [Sb@Rh12(CO)27]3− under much milder conditions of temperature and pressure. Notably, when the same synthesis was carried out under N2 instead of CO atmosphere, the new isostructural but unsaturated derivative [Sb@Rh12(CO)24]4− was obtained, for which we report the full X-ray structural characterization. This species represents one of the few examples of an icosahedral cluster disobeying the electron-counting Wade-Mingos rules, possessing less than the expected 170 cluster valence electrons (CVEs). Judging from IR monitoring, the two species can be obtained one from the other by switching between N2 and CO atmosphere, making [Sb@Rh12(CO)27]3− a spontaneous CO-releasing molecule. Finally, the study of the chemical reactivity of [Sb@Rh12(CO)27]3− with PPh3 allowed us to obtain the new [{Sb@Rh12Sb(CO)25}2Rh(CO)2PPh3]7− dimeric compound, for which we herein report the full X-ray structural and 31P NMR analyses

Atomically precise rhodium nanoclusters: synthesis and characterization of the heterometallic [Rh18Sn3Cl2(CO)33]4- and Rh7Sn4Cl10(CO)14]5- carbonyl compounds

This paper presents a deepening on the investigation of the Rh-Sn system of heterometallic carbonyl clusters. More specifically, we herein report the synthesis and isolation of the new [Rh7Sn4Cl10(CO)14]5− (1) compound and the atomically precise [Rh18Sn3Cl2(CO)33]4− (2) nanocluster. Cluster 1 can be obtained by reacting the [Rh7(CO)16]3− homometallic cluster with hydrated Sn(II) chloride, in acetone; conversely, cluster 2 derives from the previously known [Rh12Sn(CO)23Cl2]4− precursor after controlled addition of diluted sulphuric acid. Notably, only 2 has retained the recurrent Sn-centred icosahedral structural feature, while 1 shows a molecular structure based on two Rh4 tetrahedra joint by one vertex and stabilized by SnCl2 and [SnCl3]− fragments. Both species have been characterized by infrared (IR) analysis in solution, single-crystal X-ray diffraction and Electrospray Ionization Mass Spectrometry (ESI-MS)

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