Zinc Pentafluorobenzoate [Zn2(H2O)(C6F5COO)4(Py)4]: Synthesis, Structure, and Thermodynamic Characteristics

The reaction of zinc pentafluorobenzoate [Zn(H2O)(C6F5COO)2]n with a pyridine excess (Py, ratio Zn : Py = 1 : 4) affords crystals of complex [Zn2(H2O)(C6F5COO)4(Py)4] (I). The crystal packing of complex I is stabilized by numerous intra- and intermolecular interactions π…π, O…H, F…π, C–H…F, and С–H…O. The compound is characterized by the data of X-ray diffraction (XRD) (CIF file ССDС no. 2157445), IR spectroscopy, C,H,N elemental analysis, and phase XRD analysis. The vaporization of [Zn2(H2O)(C6F5COO)4(Py)4] is studied by the Knudsen effusion method with mass spectral analysis of the gas phase. This process is found to proceed in three stages with the consecutive transition of pyridine molecules to the vapor, partial hydrolysis, and congruent sublimation of zinc pentafluorobenzoate to form free molecules of Zn(C6F5)2 and СО2. The absolute partial pressures of saturated vapor and standard enthalpies of formation are calculated: $${{\Delta }_{f}}H_{{298}}^{^\circ }$$ (Zn(C6F5COO)2, s) ≤ –2634.1 ± 32.2 kJ/mol and $${{\Delta }_{f}}H_{{298}}^{^\circ }$$ (Zn(С6F5)2, g) ≤ –1422.6 ± 31.3 kJ/mol.