Lithuanian Journal of Physics article / Lietuvos fizikos žurnalo straipsnis

EXPERIMENTAL (RAMAN AND IR) AND COMPUTATIONAL (DFT) STUDIES OF THE CYCLOHEXYLTRIFLUOROSILANE
Jogilė Mačytė^a, Joanna Lach^a, M. Gregory^b, S. Gordon^b, Justinas Čeponkus^a, Valdas Šablinskas^a, and Gamil A. Guirgis^b
^aFaculty of Physics, Vilnius University, Saulėtekio 9, 10222 Vilnius, Lithuania
^bDepartment of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424, USA
Email: valdas.sablinskas@ff.vu.lt

Received 1 December 2025; accepted 21 January 2026

This study presents an experimental (Raman and IR spectroscopy) and computational (DFT) investigation of cyclohexyltrifluorosilane to identify its stable conformers and assign its experimental vibrational spectral bands. Computational analysis confirmed the existence of two stable chair conformers: chair equatorial (most stable) and chair axial. The potential energy difference between these conformers was found to be 6.3 kJ/mol, and the interconversion barrier was determined to be too high to overcome it at matrix experiments conditions. To provide a complete assignment of the compound’s vibrational spectral bands, experimental data from ATR-FTIR, Raman, and matrix isolation IR spectroscopy were used in conjunction with DFT calculations. The experimental results confirm the existence of only one conformer in the chair equatorial configuration.
Keywords: cyclohexyltrifluorosilane, matrix isolation, infrared spectroscopy, Raman spectroscopy, conformational analysis, DFT, B3LYP, cc-pVTZ

EKSPERIMENTINIAI (RAMANO IR IR SPEKTROSKOPINIAI) IR SKAIČIUOJAMIEJI (TANKIO FUNKCIONALO METODU) CIKLOHEKSILTRIFLUOROSILANO TYRIMAI
Jogilė Mačytė^a, Joanna Lach^a, M. Gregory^b, S. Gordon^b, Justinas Čeponkus^a, Valdas Šablinskas^a, Gamil A. Guirgis^b

^aVilniaus universiteto Fizikos fakultetas, Vilnius, Lietuva
^bČarlstono koledžo Chemijos ir biochemijos katedra, Čarlstonas, JAV

Šiame darbe pristatomas naujai susintetinto cikloheksiltrifluorosilano tyrimas, taikant virpesinę spektroskopiją (Ramano sklaidos ir IR spektroskopijos) bei teorinius skaičiavimus tankio funkcionalo (DFT) teoriniame artinyje. Tyrimo tikslas – nustatyti stabilias šio molekulinio junginio struktūras ir priskirti eksperimentines virpesines spektrines juostas. Skaičiavimai prognozuoja dviejų stabilių „kėdės“ konformacijų egzistavimą: „kėdės“ ekvatorinės (energiškai palankiausios) ir „kėdės“ ašinės. Šių konformacijų potencinės energijos skirtumas yra 6,3 kJ/mol, o konformacinės konversijos barjeras – 18,9 kJ/mol. Toks konversijos barjeras yra per aukštas, kad vyktų konformaciniai virsmai matricinių eksperimentų sąlygomis. Siekiant visapusiškai priskirti junginio virpesines spektrines juostas normaliesiems virpesiams, buvo panaudoti ATR-FTIR, Ramano sklaidos ir matricinės izoliacijos IR spektroskopijos eksperimentiniai duomenys kartu su DFT skaičiavimais. Eksperimentiniai spektrinių tyrimų rezultatai patvirtina, kad tiriamoje sistemoje egzistuoja tik viena stabili konformacija, t. y. „kėdės“ ekvatorinė.

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