Exploitation of Proton-Electron Cooperative-Interacting Systems with Transition Metal Complexes.

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The benzoquinone-hydrobenzoquinone complex (quinhydrone) is a DA-type CT-complex which exist as one-dimensional hydrogen bonded networks. Vibrational spectra suggest that in this complex, a proton and an electron are cooperatively transferred (PET) to give semiquinone radicals under conditions of high pressure.Cu(II) complexes with violuic acid legends (1 : [Cu(Hvi)_2(H_2O)_2]2H_2O, 2 : [Cu(Hmdvi)_2(H_2O)_2]2H_2O and 3 : [Cu(Hvi)_2(pyr)_2]2EtOH were synthesized, where the Hvi, Hmdvi and pyr denote-violuic acid, dimethyl violuic acid, and pyridine, respectively. The crystal structure and magnetic properties of these complexes were examined by means of X-ray diffraction, magnetic measurements, and powder-pattern and single-crystal ESR spectroscopy. the complex 1 has the three-dimensional hydrogen-bonded networks while the complex 2 and 3 the two-dimensional one. In the complex 1, the low-dimensional antiferromagnetic interaction was observed. On the other hand., the complex 2 and 3 exhibit the ferromagnetic and antiferromagnetic interaction, respectively. The temperature dependence of the powder-pattern ESR spectra for the complex 1 shows marked g-shifts. From single-crystal ESR spectroscopy and X-ray crystal diffraction at 173 K the marked g-shift originates in the cooperative Jahn Teller interaction assisted by the hydrogenbonded network. This is the first example illustrating that the role of the hydrogen-bonded network shows up in molecule-based magnetic materials.