Investigation of 9-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-yl)-3,3-dimethyl-2,3,4,9-tetrahydro-1H-xanthen-1-one: Crystal structure, AIM and NBO analysis

Abstract Single crystal X-ray analysis reveals that the 9-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-yl)-3,3-dimethyl-2,3,4,9-tetrahydro-1 H -xanthen-1-one, crystallizes in the centrosymmetric space group P 2 1 / c . In the crystal, molecules form as a dimer through a keto-enol type hydrogen-bonding pattern along with intermolecular C H⋯O interactions. The crystal structure of the title compound is further stabilized by intermolecular H⋯H interactions. Various intermolecular interactions present in the crystal structure are quantified by Hirshfeld surface analysis, PIXEL energy, NBO, AIM and DFT calculations. The energetics of the title compound is also compared with that of the two closely related analogs. Further, the vibrational modes of the interacting groups are characterized using both the experimental and simulated FT-IR and FT-Raman spectra. The experimental and calculated UV–visible spectra are compared and agree well. The time-dependent DFT spectra suggest that the ligand-to-ligand charge transfer within the molecule is responsible for the intense absorbance.