Heesu Jang, Jae-Seol Shim, Jung Jin Oh* (2017). Microwave spectrum of 2,6-Dimethylcyclohexanone. Journal of Molecular Spectroscopy, 337, 65-71.
DOI : 10.1016/j.jms.2017.04.021
Abstract
The rotational spectrum of 2,6-dimethylcyclohexanone (DMCHO) was measured in the frequency region from 6 to 12 GHz. Among three possible conformational isomers, two conformers were identified where two methyl groups are aligned in the equatorial/equatorial (ee) and the equatorial/axial (ea) positions. Both b-type and c-type transitions for (e,e)-2,6-DMCHO, and a-type, b-type, and c-type transitions for (e,a)-2,6-DMCHO were assigned to determine the rotational constants and quartic centrifugal distortion constants based on the Watson-A reduction Hamiltonian: (ee) A = 2150.95789(48) MHz, B = 1578.76212(40) MHz, C = 990.19141(45) MHz, ΔJ = 0.086(11) kHz, ΔJK = −0.134(20) kHz, ΔK = 0.298(15) kHz, δJ = 23.4(24) Hz, and δK = 101.4(77) Hz; and (ea) A = 2082.62538(83) MHz, B = 1566.59564(59) MHz, C = 1113.90153(75) MHz, ΔJ = 0.066(23) kHz. In addition, dipole moment components of the two isomers were determined by Stark effect measurements: (ee) μb = 2.6673(12) D, μc = 1.0379(11) D, μtotal = 2.8621(12) D; and (ea) μa = 1.385(253) D, μb = 2.358(104) D, μc = 1.172(21) D, μtotal = 2.975(144) D. Ab initio calculations for all three isomers were compared with each other and with experimental results.
Keywords
2,6-Dimethylcyclohexanone; Conformational analysis; Rotational spectrum; Dipole moments
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