Квантовохімічне дослідження просторової будови та властивостей наночастинок гідроксиду калію

• Дата: 2024
• Автор: Гребенюк, А.Г.
• Формат: Стаття
• Мова: Українська
• Опубліковано: Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine 2024
• Теми: гідроксид калію; кластер; коливальні спектри; квантовохімічне моделювання; теорія збурень Меллера – Плессета другого порядку
• Онлайн доступ: https://surfacezbir.com.ua/index.php/surface/article/view/780
• Назва журналу: Surface

Alkali metal hydroxides form layered crystals, their structure gradually becomes more complicated as the size of metal cations increases. In this work, a systematic quantum chemical analysis of the spatial structure and energy characteristics, as well as of vibrational spectra and thermodynamic parameters of molecular models for potassium hydroxide consisting of 2 – 20 formula units is performed. The structure and properties of the considered molecular models for potassium hydroxide were studied by the second-order Möller – Plesset perturbation theory method with the valence-split basis set 6 31G(d,p) using the PC GAMESS software package. In the potassium hydroxide molecule, the theoretical interatomic distances are K–O – 2.2212 Å, O–H – 0.9626 Å, respectively. During dimer and tetramer formation, the corresponding values gradually increase. Interatomic K–O distances within one bilayer block of molecular models vary from 2.62 to 2.96 Å, and those between blocks – 3.15 Å. In potassium hydroxide crystals, two-layer blocks are bound to each other by zigzag hydrogen bonds 3.35 Å long. Molecular models reproduce such bonds. The KOH molecule in the IR spectrum has 3 bands corresponding to the stretching vibrations of О–Н (3610 cm-1), K–O (408 cm-1) and bending vibration of K–O–H (300 cm 1). The calculation gives 3806, 494 and 372 cm-1, respectively. The calculated IR spectra of molecular models with interblock hydrogen bonds indicate the presence of absorption bands in different ranges: around 3800 – 3900 cm-1 (stretching vibrations of OH groups), in the range of 400 – 800 cm-1 (bending vibrations of OH groups). The cohesion energy of potassium hydroxide is 194.4 kJ/mol. Calculations of this quantity for clusters give its value in the range of 178.5 – 217.2 kJ/mol. An analysis of the calculated geometric and energy characteristics of the considered models indicates their stability and closeness to the experimental ones. These models can be used in the study of various processes that occur with the participation of potassium hydroxide.