Thermodynamics of triphenylantimony dimethylacrylate

I. Letyanina1, A. Markin1, A. Gushchin1 and D. Shashkin1

1Lobachevskiy State University of Nizhny Novgorod, Russia

Keywords: adiabatic vacuum calorimetry, combustion calorimetry
property: standard thermodynamic functions
material: antimony (V) organic compound

The chemistry of organoantimony (V) complexes attracts considerable attention of researches due to the striking structure possibilities ranging from discrete monomeric structures to supramolecular assemblies. Organoantimony derivatives exhibit significant antimicrobial properties as well as antitumor activitives. Thus synthesis and investigation of structures and physicochemical properties of organometallic compounds, particularly highly coordinated antimony compounds, are an actual task.

In the present research for the first time some thermodynamical properties of crystalline triphenylantimony dimethylacrylate Ph3Sb(O2CCМе=CH2)2 have been investigated. The sample under study has been prepared and its structure has been described in the Organic Chemistry Department in Nizhny Novgorod State University. The structure of the compound was identified by X-ray diffraction analysis. The temperature dependence of the heat capacity of crystalline Ph3Sb(O2CCМе=CH2)2 has been studied by the methods of precision adiabatic vacuum calorimetry over the range from 6 to 330 K. The heat capacity grows gradually with temperature rising in all studied range except an anomaly between 150 and 170 K. The low-temperature (20 K ≤ T ≤ 50 K) heat capacity was analyzed using the Debye’s heat capacity theory of solids and the multifractal model of heat capacity treatment. Thus the fractal dimension D was determined and the crystal structure topology was established. Obtained information has confirmed the structure of the sample solved by the X-ray diffraction analysis data. The experimental data have been used to calculate the standard thermodynamic functions: heat capacity, enthalpy, entropy and Gibbs function of crystalline Ph3Sb(O2CCМе=CH2)2 in the range from T → 0 K to 330 K. Between 310 and 500 K the behavior of the compound was studied by the methods of differential scanning calorimetry and thermogravimetric analysis. It was established that the compound melts with decomposition. The temperature of fusion has been estimated by the DSC-data.

The sample under study has been also investigated using the combustion calorimetry. Using the value of the energy of combustion of the crystalline Ph3Sb(O2CCМе=CH2)2 the standard enthalpy of combustion of the compound at T= 298.15 K has been calculated. The obtained data have been used to calculate the standard thermodynamic functions of formation (enthalpy, entropy and Gibbs energy) for crystalline Ph3Sb(O2CCМе=CH2)2 at stated temperature from the corresponding elementary substances.

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