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The synthesis of the previously‐reported atomically‐precise [Rh16Au6(CO)36]6− (1) nanocluster has been optimized by screening different reaction variables like solvent, stoichiometric ratio, counterion and atmosphere. Its multivalence properties have also been studied by means of electrochemical and spectroelectrochemical techniques; the results pointed out a remarkable electron‐sponge behaviour, as under such experimental conditions 1 is capable to release one electron and accept up to four more, while retaining its molecular structure. This scarce structural variation has been confirmed through DFT calculations on those species whose redox processes showed the maximum reversibility, namely [Rh16Au6(CO)36]7− and [Rh16Au6(CO)36]5−. Moreover, we report herein the isolation and characterization of the new [Rh10Au(CO)26]3− (2) nanocluster, which represents one of the major fallouts of the synthetic pathway investigation of 1. Finally, we disclosed the existence of further species that, from preliminary results, appear to be new large atomically‐precise Rh−Au nanoclusters, which will be the subject of future investigations. Cluster 2 has been identified via single‐crystal X‐ray diffraction analysis, and the characterization of both clusters 1 and 2 completed by infrared (IR) spectroscopy and Electrospray Ionization Mass Spectrometry (ESI‐MS). [ABSTRACT FROM AUTHOR]

The synthesis of the previously‐reported atomically‐precise [Rh16Au6(CO)36]6− (1) nanocluster has been optimized by screening different reaction variables like solvent, stoichiometric ratio, counterion and atmosphere. Its multivalence properties have also been studied by means of electrochemical and spectroelectrochemical techniques; the results pointed out a remarkable electron‐sponge behaviour, as under such experimental conditions 1 is capable to release one electron and accept up to four more, while retaining its molecular structure. This scarce structural variation has been confirmed through DFT calculations on those species whose redox processes showed the maximum reversibility, namely [Rh16Au6(CO)36]7− and [Rh16Au6(CO)36]5−. Moreover, we report herein the isolation and characterization of the new [Rh10Au(CO)26]3− (2) nanocluster, which represents one of the major fallouts of the synthetic pathway investigation of 1. Finally, we disclosed the existence of further species that, from preliminary results, appear to be new large atomically‐precise Rh−Au nanoclusters, which will be the subject of future investigations. Cluster 2 has been identified via single‐crystal X‐ray diffraction analysis, and the characterization of both clusters 1 and 2 completed by infrared (IR) spectroscopy and Electrospray Ionization Mass Spectrometry (ESI‐MS). [ABSTRACT FROM AUTHOR]

In this paper, we present a comparative study of the redox properties of the icosahedral [Rh12E(CO)27]n− (n = 4 when E = Ge or Sn and n = 3 when E = Sb or Bi) family of clusters through in situ infrared spectroelectrochemistry experiments and density functional theory computational studies. These clusters show shared characteristics in terms of molecular structure, being all E-centered icosahedral species, and electron counting, possessing 170 valence electrons as predicted by the electron-counting rules, based on the cluster-borane analogy, for compounds with such metal geometry. However, in some cases, clusters of similar nuclearity, and beyond, may show multivalence behavior and may be stable with a different electron counting, at least on the time scale of the electrochemical analyses. The experimental results, confirmed by theoretical calculations, showed a remarkable electron-sponge behavior for [Rh12Ge(CO)27]4− (1), [Rh12Sb(CO)27]3− (3), and [Rh12Bi(CO)27]3− (4), with a cluster charge going from −2 to −6 for 1 and 3 and from −2 to −7 for cluster 4, making them examples of molecular electron reservoirs. The [Rh12Sn(CO)27]4− (2) derivative, conversely, presents a limited ability to exist in separable reduced cluster species, at least within the experimental conditions, while in the gas phase it appears to be stable both as a penta- and hexa-anion, therefore showing a similar redox activity as its congeners. As a fallout of those studies, during the preparation of [Rh12Sb(CO)27]3−, we were able to isolate a new species, namely, [Rh11Sb(CO)26]2−, which presents a Sb-centered nido-icosahedral metal structure possessing 158 cluster valence electrons, in perfect agreement with the polyhedral skeletal electron pair theory. [ABSTRACT FROM AUTHOR]

The hetero-metallic [Sb@Rh 12 (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@Rh 12 (CO) 27 ] 3 − under much milder conditions of temperature and pressure. Notably, when the same synthesis was carried out under N 2 instead of CO atmosphere, the new isostructural but unsaturated derivative [Sb@Rh 12 (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 N 2 and CO atmosphere, making [Sb@Rh 12 (CO) 27 ] 3 − a spontaneous CO-releasing molecule. Finally, the study of the chemical reactivity of [Sb@Rh 12 (CO) 27 ] 3 − with PPh 3 allowed us to obtain the new [{Sb@Rh 12 Sb(CO) 25 } 2 Rh(CO) 2 PPh 3 ] 7 − dimeric compound, for which we herein report the full X-ray structural and 31 P NMR analyses. [ABSTRACT FROM AUTHOR]