A general approach to the theoretical evaluation of the crystal lattice energy of ionic substances, particularly those composed of monoatomic ions, is outlined in detail. Subsequently, the possibilities of theoretical prediction of the lattice energy of complex organic and inorganic ionic substances are discussed. Lastly, the importance of the lattice energy in examinations of the properties and behaviour of solid-state systems, is treated, together with the prospects of developing a model describing the kinetics of solid-state processes.
Theoretical possibilities of determining energetic and thermodynamic characteristics of chemical entities in gaseous and condensed
(solid and liquid) phases are briefly reviewed. The considerations include quantum chemistry methods which enable evaluation
of energetic quantities and statistical thermodynamics dependencies necessary for determining other thermodynamic characteristics.
The possible applications of these methods are also discussed in brief.
The main reasons for changes in the environment surrounding us are discussed on the basis of thermodynamics of irreversible
processes. Subsequently, relations between thermodynamics of irreversible processes and chemical kinetics are shown, then
the possibilities of theoretical determination of rate constants on the framework of the modified RRKM theory are presented.
These latter considerations are supplemented by a discussion concerning the possibilities of determining the activation barriers
and structural changes (necessary to account for entropy changes upon reaction) in molecules kept on the surface of crystalline
phases by combination of quantum chemistry methods for isolated molecules with those reflecting the influence of the environment
(i.e. interaction within the lattice). Finally, the future of theoretical methods in examining the reactivity of solid state
systems is briefly discussed.
Authors:P. Storoniak, K. Krzymiński, and J. Błażejowski
Enthalpies of sublimation of acridine, 9-acridinamine, N-methyl-9-acridinamine, 10-methyl-9-acridinimine, N,N-dimethyl-9-acridinamine
and N-methyl-10-methyl-9-acridinimine were determined by fitting to thermogravimetric curves with the Clausius-Clapeyron relationship.
These values compare well with crystal lattice energies predicted theoretically as the sum of electrostatic, dispersive and
repulsive interactions. Partial charges for these calculations were obtained on an ab initio level, while atomic parameters
were taken from literature.
Authors:P. Skurski, M. Jasionowski, and J. Błażejowski
MNDO/d and PM3 quantum chemistry methods were used to examine reaction pathways and predict thermodynamic and kinetic barriers
for the thermal dissociation of isolated conglomerates of N,N,N-trimethylmethanaminium cations (TMA+) and halide anions (X = Cl−, Br− and I−). Theoretically obtained changes in enthalpy and entropy for the above-mentioned process were subsequently supplemented with
theoretically determined crystal lattice energies, that enabled prediction of relevant characteristics for the dissociation
of crystalline phases. Data thus obtained compare only qualitatively with those available in literature and resulting predominantly
from thermoanalytical investigations, although values of theoretical characteristics generally follow the same trends as experimental
Authors:P. Storoniak, M. Kabir, and J. Błażejowski
The enthalpies of formation of PbCl4, PbCl5− and PbCl62−, originating from quantum mechanics, have enabled the thermodynamic behaviour of these ions with respect to Cl-detachment
to be assessed. The stability of salts containing PbCl5− and PbCl62− as a function of the dimensions of these anions and complementary cations was studied using an approach combining the Kapustinskii-Yatsimirskii
equation with basic thermochemical relationships.
It was found that hexachloroplumbates of monovalent metal cations will not dissociate into metal chlorides and PbCl4, provided the complementary cations are suitably large in size. Hexachloroplumbates of divalent metal cations have not yet
been synthesised since no known metal cations attain the requisite large size. Such salts will not dissociate if the divalent
metal cations are able to complex suitably large electron-donating ligands. The pentachloroplumbates of both monovalent and
divalent metal cations are unstable, since no known metal cations have appropriately large ionic radii. The approach adopted
appears to be useful for the examination of the thermal behaviour, stability and reactivity of chloroplumbates.