Calorimetric Study of Triphenylbismuth Dimethacrylate Ph₃Bi(O₂CCMeCH₂)₂

In the present research, the heat capacities of triphenylbismuth dimethacrylate Ph₃Bi­(O₂CCMeCH₂)₂ were measured between <i>T</i> = 5.3 and 330 K with the precision adiabatic vacuum calorimeter and from <i>T</i> = 310 to 420 K with the differential scanning calorimeter. There revealed a reproducible anomaly from 150 to 170 K caused by structural changes in the crystal lattice, and intensive exothermic transition over the range from <i>T</i> = 385 to 420 K caused by the reductive decomposition with the polymerization of the sample under study. The experimental results were used to calculate the standard (<i>p</i> = 0.1 MPa) thermodynamic functions (heat capacity <i>C</i>_p,m^o, enthalpy <i>H</i>_m^o(<i>T</i>) – <i>H</i>_m^o(0), entropy <i>S</i>_m^o(<i>T</i>), and Gibbs energy Φ_m^o(<i>T</i>) of crystalline triphenylbismuth dimethacrylate from <i>T</i> → 0 to 385 K. The standard entropy of formation at <i>T</i> = 298.15 K was calculated for the compound under study in the crystalline state. Obtained for Ph₃Bi­(O₂CCMeCH₂)₂ results were compared with ones for Ph₃Sb­(O₂CCMeCH₂)₂