Messanae Universitas Studiorum

Magnetic-, ESR and Quantumchemical Investigations on Penta- and Hexa- Coordinated Manganese (II) Complexes

Linert, Wolfgang and Boca, Roman and De Marco, Domenico (1996) Magnetic-, ESR and Quantumchemical Investigations on Penta- and Hexa- Coordinated Manganese (II) Complexes. Accademia Peloritana dei Pericolanti - Classe di Scienze FF.MM.NN., LXXIV (1). pp. 37-57.

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    Abstract

    Two manganese(II) complexes with the tridentate ligand 2,6-bis(benzimidazol-2-yl)pyridine, namely $[Mn(bzimpy)_2](ClO_4)_2$, 1, and $[Mn(bzimpy)Cl_2]$ * 0.5MeOH, 2, have been investigated by magnetic AC susceptibility measurements in the temperature range of 18 to 300 K. Electron spin resonance has been performed in solid state and frozen solution at 77 K. Parameters for the magnetic contributions to the Hamiltonian received by these techniques confirm axial magnetic anisotropy. ACS data are: $g_av = 1.92±0.04$, $|D/hc| = 0.9±1.3 cm^-1$ and $g_av = 1.89$, $|D/hc| = 1.4 cm^-1$ for 1, and 2, respectively. The three found ESR resonances correspond to $g_eff^(1) = 1.99$, $g_eff^(2) = 3.3$ and $g_eff^(3) = 4.3$. The highest field resonance exhibits a hyperfine sextet splitting of $|A_av/hcl| = 92 x 10^-4 cm^-1$ for both complexes. Well resolved forbidden transitions allow for an estimation of the zero-field splitting parameter being $D/hc = -0.09 and 0.13 cm^-1$ for the two complexes, respectively. $Ab$ $initio$ MO-LCAO-SCF calculations on a double-zeta basis set indicate that complex 2 should be more stable than $1$. The calculations yielded also information about electronic structure, bond-strenghts and charge distributions within the complexes.

    Item Type: Article
    Subjects: M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Fisiche, Matematiche e Naturali
    Divisions: UNSPECIFIED
    Depositing User: Dr PP C
    Date Deposited: 19 Sep 2012 11:51
    Last Modified: 21 Sep 2012 12:22
    URI: http://cab.unime.it/mus/id/eprint/565

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