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Issue 17, 1998
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Molecular structure of monomeric scandium trichloride by gas electron diffraction and density functional theory calculations on ScCl3 and Sc2Cl6

Abstract

The molecular structures of monomeric and dimeric scandium trichloride were optimised by DFT calculations with basis sets of valence shell TZ + P quality, and the molecular force fields and normal vibrational modes calculated. Optimisation of ScCl3 yielded an equilibrium geometry of D3h symmetry and bond distance Sc–Cl 228.5 pm. Optimisation of a model of the dimer with double Cl bridges indicated an equilibrium geometry of D2h symmetry, the terminal and bridging bond distances Sc–Clt 226.0 and Sc–Clb 247.5 pm, and the valence angles Clt–Sc–Clt 114.9 and Clb–Sc–Clb 86.6°. Synchronous gas electron diffraction (GED) and mass spectrometric (MS) data were recorded with the effusion cell kept at 900 ± 10 K. The gas was found to consist of 92 ± 2% monomer and 8 ± 2% dimer. Least-squares refinement of a trigonal pyramidal (C3v) model of the monomer yielded the bond distance rg(Sc–Cl) = 229.1(3) pm and a valence angle α Cl–Sc–Cl 119.8(5)°. The concentration of the dimer was too low for the GED data to give accurate structure parameters for this species. Bond energies for both monomer and dimer were calculated from thermochemical data in the literature and compared to corresponding energies in MCl3 and M2Cl6, M = Al, Ga or In.

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Article type: Paper
DOI: 10.1039/A803339K
Citation: J. Chem. Soc., Dalton Trans., 1998,0, 2787-2792
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    Molecular structure of monomeric scandium trichloride by gas electron diffraction and density functional theory calculations on ScCl3 and Sc2Cl6

    A. Haaland, K. Martinsen, D. J. Shorokhov, G. V. Girichev and V. I. Sokolov, J. Chem. Soc., Dalton Trans., 1998, 0, 2787
    DOI: 10.1039/A803339K

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