Structures and Heats of Formation of Simple Alkaline Earth Metal Compounds II: Fluorides, Chlorides, Oxides, and Hydroxides for Ba, Sr, and Ra

Abstract

Geometry parameters, vibrational frequencies, heats of formation, bond dissociation energies, cohesive energies, and selected fluoride affinities (difluorides) are predicted for the late alkaline earth (Sr, Ba, and Ra) oxides, fluorides, chlorides, and hydroxides at the coupled cluster theory CCSD(T) level. Additional corrections (scalar relativistic and pseudopotential corrections, vibrational zero-point energies, and atomic spin-orbit effects) were included to accurately calculate the total atomization energies and heats of formation following the Feller-Peterson-Dixon methodology. The calculated values are compared to the experimental data where available. In some cases, especially for Ra compounds, there are no experimental results, or the experimental energetics and geometries are not reliable or have very large error bars. All of the Sr, Ba, and Ra difluorides, dichlorides, and dihydroxides are bent structures with the OMO bond angles decreasing going down the group. The cohesive energies of bulk Be dihalides are predicted to be quite low, while those of Ra are relatively large. The fluoride affinities show that the difluorides are moderately strong Lewis acids and that such trifluorides may form under the appropriate experimental conditions.

Stability and Electronic Properties of Rocksalt (CdO)n, (SrO)n, and (BaO)n Nanoparticles

“…3–4 kcal/mol). With the energy decomposition approach, NCE(∞) is evaluated to be 142.7 kcal/mol at the HSE06 level for SrO (Table S1 in the SI), only 2 kcal/mol from the experimental value (140.5 kcal/mol obtained from the heats of formation of −141.5 kcal/mol for the bulk and our current FPD calculated value of −1.0 kcal/mol for the gas-phase diatomic). Based on the overall performances of the tested functionals at both the small cluster and bulk limits, we chose to use the HSE06 functional for the energy predictions for (SrO) n .…”

Chemistry of alkaline earth metals: It is not all ionic and definitely not boring!

“…For unambiguously bent molecules, like SrF 2 , BaCl 2 , or BaBr 2 , the barrier to linearity is below 8 kJ/mol, and only BaF 2 was found to possess a bending energy of 25 kJ/mol. A very recent theoretical study resumes the geometry of the heavier alkaline earth metal halides and hydroxides, some of which are exemplarily resumed in Table 1 [101,102].…”

“…Calculated and experimental bond distances and angles for the alkaline earth fluorides and chlorides[100][101][102].…”

Thermodynamics of Metal Carbonates and Bicarbonates and Their Hydrates for Mg, Ca, Fe, and Cd Relevant to Mineral Energetics

“…In general, however, it is not clear how accurate such methods are for the prediction of thermodynamic quantities of the simple species that make up the monomers in mineral systems. We have previously reported reliable calculated gas phase thermodynamic properties for a number of simple alkali and alkaline earth compounds in the gas phase, − and then, we used these values to predict the cohesive energy of different solid materials using the Feller–Peterson–Dixon (FPD) approach. − This approach is based on extrapolating CCSD­(T) energies to the complete basis set (CBS) limit and including additional corrections to the total atomization energy (TAE) with the goal of achieving chemical accuracy of ±1 kcal/mol in the predictions.…”