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Issue 1, 2012
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Activation of C–Cl by ground-state aluminum atoms: an EPR and DFT investigation

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Abstract

The reaction of ground-state Al atoms with dichloromethane (CH2Cl2) in an adamantane matrix at 77 K yielded two mononuclear Al species. The magnetic parameters, extracted from the axial EPR spectrum of Species A/A′ (g1 = 2.0037, g2 = g3 = 2.0030, aAl,1 = 1307 MHz, aAl,2 = aAl,3 = 1273 MHz, a35Cl = 34 MHz and a37Cl = 28 MHz) were assigned to the Al-atom insertion product, ClCH2AlCl. Density functional theory (DFT) calculations of the values of the Al and Cl hyperfine interaction (hfi) of the Cl1–Cl2gauche conformer were in close agreement with the experimental values of ClCH2AlCl. The second species, B/B′, had identical magnetic parameters to those of ClCH2AlCl with the exception that the Al hfi was 15% smaller. Coordination of a ligand, possessing a lone pair of electrons, to the Al atom of the insertion product, [ClCH2AlCl]:X, could cause the aAl to decrease by 15%. Alternatively, it is possible that the Cl1–Cl2 anti conformer of ClCH2AlCl is also isolated in the matrix. Support for the spectral assignments is given by calculation of the nuclear hfi of [ClCH2AlCl]:H2O and the Cl1–Cl2 anti conformer of ClCH2AlCl using a DFT method. The potential energy hypersurface for an Al atom approaching CH2Cl2, calculated at the B3LYP level, suggests that Al atom abstraction of Cl forming AlCl and CH2Cl is favoured in the gas phase. When produced in a matrix, the close proximity of AlCl and CH2Cl could account for the formation of ClCH2AlCl. EPR evidence was also found for the formation of the CHCl2 radical.

Graphical abstract: Activation of C–Cl by ground-state aluminum atoms: an EPR and DFT investigation

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Publication details

The article was received on 24 Jul 2011, accepted on 28 Oct 2011 and first published on 16 Nov 2011


Article type: Paper
DOI: 10.1039/C1CP22398D
Phys. Chem. Chem. Phys., 2012,14, 367-374

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    Activation of C–Cl by ground-state aluminum atoms: an EPR and DFT investigation

    H. A. Joly, T. Newton and M. Myre, Phys. Chem. Chem. Phys., 2012, 14, 367
    DOI: 10.1039/C1CP22398D

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