ИСТИНА

The molecular systems exhibiting the bi-stable behavior are considered to be promising for application in molecular electronics. One of the examples of molecular bi-stability is spin-crossover (SCO) phenomena, meaning that the system can be stabilized in different electronic states by varying the external conditions (pressure, temperature or magnetic field, by irradiation exposing). This study is focused on the investigation of temperature induced SCO phenomena in [Mn(5-Cl-sal-N-1,5,8,12)]TCNQ1.5 2CH3CN (I) and [Mn(5-Br-sal-N-1,5,8,12)]TCNQ1.5 2CH3CN complexes (II). There are several aspects making these objects particularly interesting. First, SCO is commonly observed in molecular complexes based on Fe (II), Fe (III) and Co (II) and not so often in Mn (III) -based compounds. Second, the SCO with wide thermal hysteresis loop is relatively rare phenomena, it is impossible to predict. Third, the studied system combine the SCO behavior and conductive properties, that makes it the first conducting SCO compound based on Mn (III) cation with TCNQ in factional reduction state. Here, we present the results of studying the magnetic properties, heat capacity and structural characterization of compounds I and II. Examination of the temperature dependence of magnetic susceptibility χ(T) revealed the SCO in compound I. Specifically, the complex I exhibits a sharp SCO at about 120 K with wide thermal hysteresis loop in χ(T) suggesting the significant cooperativity for the transition. The magnitude and form of χ(T) hysteretic loop observed in compound I is sustainable after several thermal cycling measurements thus proving the reproducibility of observed SCO behavior in I. Compound II did not show SCO behavior manifesting the significant role of the environment.