Vibrational spectra of tris(acetylacetonato)chromium(III)

Abstract

The molecular structure and vibrational spectra of tris(acetylacetonato)chromium(III), Cr (AA)3, its<br><br>mono-deuterated, Cr (DAA)3, and per-deuterated analogous, Cr(D7AA)3, were investigated using density functional theory (DFT) calculations. The geometry of the titled compound was fully optimized at the B3LYP level using 6-311 þ G* and 6-31G** basis sets. The harmonic vibrational frequencies were obtained at the B3LYP/6-311 þ G** level. Raman scattering activities were calculated at the 3LYP/6-31G** level.<br><br>The calculated frequencies are compared with the experimental IR and Raman spectra. All of the<br><br>measured IR and Raman bands were interpreted in terms of the calculated vibrational modes and isotopic<br><br>frequency shifts. The scaled theoretical frequencies and the structural parameters are in excellent<br><br>agreement with the experimental data. Analysis of the vibrational spectra indicates a strong coupling<br><br>between the chelated ring modes. Several bands at 933, 680, 611, 594, 495, 250, 224, and 179 cm-1 are found to be engaged in CreO vibrational movements. The IR bands at 611 and 594 cm-1 are attributed to the asymmetric CreO stretching and the very strong Raman band at 460 cm-1 is assigned to the totally symmetric CreO stretching mode (a1 species).