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Title

Assessing Metal-Metal Multiple Bonds in Cr-Cr, Mo-Mo, and W-W Compounds and a Hypothetical U-U Compound: A Quantum Chemical Study Comparing DFT and Multireference Methods

Authors
Dzubak, Allison L.
Mulla, Abbas
Brogden, David W.
Berry, John F.
Published in Chemistry - A European Journal. 2012, vol. 18, no. 6, p. 1737-1749
Abstract To gain insights into the trends in metal–metal multiple bonding among the Group 6 elements, density functional theory has been employed in combination with multiconfigurational methods (CASSCF and CASPT2) to investigate a selection of bimetallic, multiply bonded compounds. For the compound [Ar-MM-Ar] (Ar=2,6-(C6H5)2-C6H3, M=Cr, Mo, W) the effect of the Ar ligand on the M2 core has been compared with the analogous [Ph-MM-Ph] (Ph=phenyl, M=Cr, Mo, W) compounds. A set of [M2(dpa)4] (dpa=2,2′-dipyridylamide, M=Cr, Mo, W, U) compounds has also been investigated. All of the compounds studied here show important multiconfigurational behavior. For the Mo2 and W2 compounds, the σ2π4δ2 configuration dominates the ground-state wavefunction, contributing at least 75 %. The Cr2 compounds show a more nuanced electronic structure, with many configurations contributing to the ground state. For the Cr, Mo, and W compounds the electronic absorption spectra have been studied, combining density functional theory and multireference methods to make absorption feature assignments. In all cases, the main features observed in the visible spectra may be assigned as charge-transfer bands. For all compounds investigated the Mayer bond order (MBO) and the effective bond order (EBO) were calculated by density functional theory and CASSCF methods, respectively. The MBO and EBO values share a similar trend toward higher values at shorter normalized metal–metal bond lengths.
Keywords Bond theoryDensity functional calculationsElectronic statesMetal|metal interactionsQuantum chemistry
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Other version: http://doi.wiley.com/10.1002/chem.201103096
Structures
Research group Groupe Wesolowski
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LI MANNI, Giovanni et al. Assessing Metal-Metal Multiple Bonds in Cr-Cr, Mo-Mo, and W-W Compounds and a Hypothetical U-U Compound: A Quantum Chemical Study Comparing DFT and Multireference Methods. In: Chemistry - A European Journal, 2012, vol. 18, n° 6, p. 1737-1749. https://archive-ouverte.unige.ch/unige:18373

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Deposited on : 2012-02-13

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