کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5414364 | 1506722 | 2016 | 4 صفحه PDF | دانلود رایگان |
- The first, high resolution microwave measurements of rotational transitions for maleimide.
- Accurate rotational constants are used to determine structural parameters for maleimide.
- High-level DFT calculations using yielded rotational constants within 2% of measured values.
- Nitrogen quadrupole coupling parameters were obtained for maleimide.
The rotational spectrum of maleimide was measured in the 5-12 GHz range using a Flygare-Balle type, pulsed-beam Fourier transform microwave spectrometer. Rotational transitions were measured for the parent, all unique singly substituted 13C isotopologues, and an ND, deuterium substituted isotopologue. The parent (or normal isotopologue) rotational constants, centrifugal distortion constants, and quadrupole coupling constants are A = 6815.3251(12) MHz, B = 2361.85011(64) MHz, C = 1754.32750(64) MHz, DJ = 0.232(24) kHz, DJK = 0.546(54) kHz, 1.5Ïaa = 2.4227(53) MHz, and 0.25(Ïbb-Ïcc) = 1.3679(15) MHz. A best fit gas phase structure was determined using the experimental rotational constants of the isotopologues and some parameters from calculations. The inertial defect is Π= â0.054 amu à 2, indicating a planar structure for maleimide, with no large amplitude motions observed on the NH hydrogen atom. Calculations using B3LYP/aug-cc-pVTZ provided rotational constants which are much closer (within 1-2%) to the experimental values compared to the MP2/aug-cc-pVTZ calculated values.
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Journal: Journal of Molecular Spectroscopy - Volume 319, January 2016, Pages 26-29