Mg+ligand binding energies

NASA Ames Research Center, Moffett Field, CA 94035, USA
Chemical Physics Letters (Impact Factor: 2.15). 06/1991; 181(s 2–3):129–133. DOI: 10.1016/0009-2614(91)90344-9

ABSTRACT Ab initio calculations are used to optimize the structures and determine the binding energies of Mg+ to a series of ligands. Mg+ bonds electrostatically with benzene, acetone, H2, CO, and NH3 and a self-consistent-field treatment gives a good description of the bonding. The bonding in MgCN+ and MgCH+3 is largely covalent and a correlated treatment is required.

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    ABSTRACT: Photodissociation spectra of mass-selected Mg(CH2�CHCN)n+ cluster ions were investigated in the wavelength region from 415 to 225 nm and 495 to 225 nm for n = 1 and 2, respectively, by monitoring the total yield of fragment ions. The absorption bands exhibit large shifts from the 2P–2S resonance line of Mg+. In the spectrum of n = 1, there are two bands at 26 400 and 40 800 cm−1. On the other hand, three absorption bands at 22 600, 28 800, and 37 500 cm−1 appear in the spectrum of n = 2. The most stable structures in the ground state for n = 1 and 2 were obtained by DFT(B3LYP/6-31+G∗) calculations, and transition energies from these structures were obtained by using configuration interaction singles approach with the same basis set. The calculated excitation energies show good agreement with the experimental results. In addition, fragment ions of Mg(CH2�CHCN)m+ with m = 4 and 5 are found to have high intensities from the parent ions of n = 6–10 at a dissociation wavelength of 355 nm. From the result of theoretical calculations for n = 3 and 4, a valence electron of Mg+ is found to transfer to the solvating acrylonitrile molecules in these sizes, although this process does not cause an anionic polymerization reaction that observed in alkali metal atom-acrylonitrile neutral clusters. © 2003 American Institute of Physics.
    The Journal of Chemical Physics 03/2003; 118(12):5456-5464. · 3.12 Impact Factor
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    ABSTRACT: We have studied the structure and photodissociation of Mg(+)-acetic acid clusters. Ab initio calculations suggest four relatively strongly bound ground state isomers for the [MgC(2)H(4)O(2)](+) complex. These isomers include the cis and trans forms of the Mg(+)-acetic acid association complex with Mg(+) bonded to the carbonyl O atom of acetic acid, the Mg(+)-acetic acid association complex with Mg(+) bonded to the hydroxyl O atom of acetic acid, or to a Mg(+)-ethenediol association complex. Photodissociation through the Mg(+)-based 3p<--3s absorption bands in the near UV leads to direct (nonreactive) and reactive dissociation products: Mg(+), MgOH(+), Mg(H(2)O)(+), CH(3)CO(+), and MgCH(3) (+). At low energies the dominant reactive quenching pathway is through dehydration to Mg(H(2)O)(+), but additional reaction channels involving C-H and C-C bond activation are also open at higher energies.
    The Journal of Chemical Physics 11/2006; 125(18):184310. · 3.12 Impact Factor
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    ABSTRACT: Photodissociation spectra for mass-selected Mg(+)(NH(3))(n) clusters for n=1 to 7 are reported over the photon energy range from 7000 to 38 500 cm(-1). The singly solvated cluster, which dissociates primarily via a N-H bond cleavage, exhibits a resolved vibrational structure corresponding to two progressions in the intracluster Mg(+)-NH(3) modes. The addition of the second, third, and fourth solvent molecules results in monotonic redshifts that appear to halt near 8500 cm(-1), where a sharp feature in the electronic spectrum is correlated with the formation of a Mg(+)(NH(3))(4) complex with T(d) symmetry and the closing of the first solvation shell. The spectra for the clusters with 5 to 7 solvent molecules strongly resemble that for the tetramer, suggesting that these solvent molecules occupy a second solvation shell. The wavelength-dependent branching-ratio measurements show that increasing the photon energies generally result in the loss of additional solvent molecules but that enhancements for a specific solvent number loss may reveal special stability for the resultant fragments. The majority of the experimental evidence suggests that the decay of these clusters occurs via the internal conversion of the initially excited electronic states to the ground state, followed by dissociation. In the case of the monomer, the selective cleavage of a N-H bond in the solvent suggests that this internal-conversion process may populate regions of the ground-state surface in the vicinity of an insertion complex H-Mg(+)-NH(2), whose existence is predicted by ab initio calculations.
    The Journal of Chemical Physics 12/2004; 121(17):8375-84. · 3.12 Impact Factor