Matrix-isolation IR spectroscopy of R-(+)-3-methylcyclopentanone in para-hydrogen crystal

High-resolution infrared (IR) spectra of R-(+)-3-methylcyclopentanone (R3MCP) in para-hydrogen (pH₂) crystal were recorded and compared with the corresponding IR spectra of R3MCP in Argon (Ar) isolation matrix as well as the IR spectra of the neat crystalline R3MCP at low deposition temperature of 4 ± 0.05 K. Moreover, IR spectra of R3MCP, hosted in pH₂ crystal, were recorded using a high-resolution Fourier transform IR spectrometer as a function of sample concentration and over the range 10-300 ppm. Furthermore, density functional theory calculations of simulated IR spectra for the optimized geometries of R3MCP equatorial-methyl and axial-methyl conformers are compared with experimental spectra for the purpose of investigating molecular conformation. Upon comparison between theoretical and experimental IR spectra, vibrational modes arising from equatorial and axial conformers have been successfully assigned and related to the individual conformer's structure.