Examinando por Autor "Kahlal, Samia"

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    4-: Coinage Metal Tetrahedral Superatoms as Useful Building Blocks Related to Pyramidal Au20 Clusters (M = Cu, Ag, Au). Electronic and Bonding Properties from Relativistic DFT Calculations
    (American Chemical Society, 2018-03) Gam, Franck; Arratia-Pérez, Ramiro; Kahlal, Samia; Saillard, Jean-Yves; Muñoz-Castro, Álvaro
    Characterization of the tetrahedral Au20 structure in the gas phase remains a major landmark in gold cluster chemistry, where further efforts to stabilize this bare 20-electron superatom in solution to extend and understand its chemistry have failed so far. Here, we account for the structural, electronic, and bonding properties of [M16Ni24(CO)40]4- (M = Cu, Ag, Au) observed in solution for gold and silver. Our results show a direct electronic relationship with Au20, owing that such species share a common tetrahedral [M16]4- central core with a 1S21P61D102S2 jellium configuration. In the case of Au20, the [Au16]4- core is capped by four Au+ ions, whereas in [M16Ni24(CO)40]4- it is capped by four Ni6(CO)10 units. In both cases, the capping entities are a full part of the superatom entity, where it appears that the free (uncapped) [M16]4- species must be capped for further stabilization. It follows that the Ni6(CO)10 units in [M16Ni24(CO)40]4- should not be considered as external ligands as their bonding with the [M16]4- core is mainly associated with a delocalization of the 20 jellium electrons onto the Ni atoms. Thus, the [M16Ni24(CO)40]4- species can be seen as the solution version of tetrahedral M20 clusters, encouraging experimental efforts to further develop the chemistry of such complexes as M(111) finite surface section structures, with M = Ag and Au and, particularly promising, with M = Cu. Furthermore, optical properties were simulated to assist future experimental characterization. © 2018 American Chemical Society.
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    Non-covalent interactions in hexanuclear polyoxidometalates [VIV6B20O50H8]8−. An experimental and theoretical approach
    (Elsevier Ltd, 2022-01-01) Muñoz-Becerra, Karina; Wrighton-Araneda, Kerry; Le Fur, Eric; Saillard, Jean-Yves; Kahlal, Samia; Cador, Olivier; Paredes-García, Verónica; Venegas-Yazigi, Diego
    A complete study of the optical and magnetic properties of three new {V6-type} polyoxidometalates (NH3CH2CH2CH2NH3)4{V6B20O50H8}·4H2O 1, K2(NH3CH2CH2NH3)2.5(NH3CH2CH2NH2){V6B20O50H8}·2H2O 2, and K2(NH3CH2CH2CH2NH3)2(H3O)2{V6B20O50H8}·8H2O 3 is presented. Using TD-DFT calculations, the assignment of the experimental UV–Visible spectra was established with four absorption bands: a higher in energy assigned to metal-to-metal charge transfer and the remaining associated principally to d-d transitions, demonstrating that the {V6IVO18}12− ring is the principal chromophore for these systems and that the surrounding packing does not have an influence on it. On the other hand, the differences observed in the magnetic properties are caused by the influence of the non-covalent interactions between the potassium ions with some oxygen atoms of the VIV coordination spheres, thus modifying the VIV-VIV exchange coupling. This effect was demonstrated using a simplified binuclear DFT model that predicts a higher VIV-VIV antiferromagnetic coupling when the K cations become closer to the oxygen bridge atoms that link the VIV centres of the {V6IVO18}12− ring. © 2021