title: Physical and Structural Characterization of Imidazolium-Based Organic-Inorganic Hybrid: (C3N2H5)2[CoCl4].
abstract: (C3N2H5)2[CoCl4] (ICC) was characterized in a wide temperature range by the single-crystal X-ray diffraction method. Differential scanning calorimetry revealed two structural phase transitions: continuous at 245.5 K (from phase I to II) and a discontinuous one at 234/237 K (cooling/heating) (II → III). ICC adopts monoclinic space groups C2/c and P21/c in phase (I) and (III), respectively. The intermediate phase (II) appears to be incommensurately modulated. Dynamic properties of polycrystalline ICC were studied by means of dielectric spectroscopy and proton magnetic resonance ((1)H NMR). The presence of a low frequency dielectric relaxation process in phase III reflects libration motion of the imidazolium cations. The temperature dependence of the (1)H spin-lattice relaxation time indicated two motional processes with similar activation energies that are by about an order of magnitude smaller than the activation energy obtained from dielectric studies. There are no abrupt changes in the (1)H relaxation time at the phase transitions indicating that the dynamics of the imidazolium rings gradually varies with temperature; that is, it does not change suddenly at the phase transition. Negative values of the Weiss constant and the intermolecular exchange parameter were obtained, confirming the presence of a weak antiferromagnetic interaction between the nearest cobalt centers. Moreover, the magnitude of zero field splitting was determined. The AC susceptibility measurements show that a slow magnetic relaxation is induced by small external magnetic field.
authors.affiliation: Faculty of Chemistry, University of Wrocław , 14 F. Joliot-Curie, 50-383 Wrocław, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Piecha-Bisiorek
authors.affiliation: Faculty of Chemistry, University of Wrocław , 14 F. Joliot-Curie, 50-383 Wrocław, Poland.
authors.forename: Alina
authors.initials: A
authors.lastname: Bieńko
authors.affiliation: Faculty of Chemistry, University of Wrocław , 14 F. Joliot-Curie, 50-383 Wrocław, Poland.
authors.forename: Ryszard
authors.initials: R
authors.lastname: Jakubas
authors.affiliation: Department of Chemistry, FPV, University of SS Cyril and Methodius , Trnava, Slovakia.
authors.forename: Roman
authors.initials: R
authors.lastname: Boča
authors.affiliation: Faculty of Chemistry, University of Wrocław , 14 F. Joliot-Curie, 50-383 Wrocław, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Weselski
authors.affiliation: Institute of Low Temperature and Structure Research , PAS, Okólna 2, 50-422 Wrocław, Poland.
authors.forename: Vasyl
authors.initials: V
authors.lastname: Kinzhybalo
authors.affiliation: Institute of Low Temperature and Structure Research , PAS, Okólna 2, 50-422 Wrocław, Poland.
authors.forename: Adam
authors.initials: A
authors.lastname: Pietraszko
authors.affiliation: Faculty of Chemistry, University of Wrocław , 14 F. Joliot-Curie, 50-383 Wrocław, Poland.
authors.forename: Martyna
authors.initials: M
authors.lastname: Wojciechowska
authors.affiliation: Institute of Molecular Physics , PAS, M. Smoluchowskiego 17, 60-179 Poznań, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Medycki
authors.affiliation: Faculty of Mathematics and Computer Science, University of Warmia & Mazury , Słoneczna 54, 10-710 Olsztyn, Poland.
authors.forename: Danuta
authors.initials: D
authors.lastname: Kruk