Microwave spectrum, molecular structure, dipole moment, and quantum chemical calculations of s-trans-(E)-2-methyl-2-propenal oxime
Abstract
The spectroscopic constants of s-trans-(E)-2-methyl-2-propenal oxime (methacryl- aldehyde oxime) of normal, H2Cdbnd C(CH3)sbnd CHdbnd NOH, and its deuterated species, H2Cdbnd C(CH3)sbnd CHdbnd NOD, were determined by observing their microwave spectra in the frequency range of 8 to 40 GHz in the ground vibrational state. The rotational constants were A = 8321.38(82), B = 2076.09(1), and C = 1678.60(1) MHz for normal species and A = 8283.7(16), B = 1998.63(2), and C = 1626.21(2) MHz for deuterated species, respectively. The inertial defects (ΔI = Ic - Ia - Ib) of normal and deuterated species were determined to be -3.09(2) and -3.10(3) uÅ2, respectively. The dipole moments were determined as μa = 0.53(2), μb = 0.27(2), and μtotal = 0.60(5) D. The 14N nuclear quadrupole coupling constants were determined as χaa = 3.62(12), χbb = -5.1(14), and χcc = 1.48(26) MHz. The comparison of the observed spectroscopic parameters with the calculated ones led to the conclusion that the assigned spectrum was due to s-trans-(E) form. The rs coordinates of the hydrogen atom in a hydroxyl group were determined and the OH bond was found to be at the trans position with respect to the Cdbnd N double bond. The structural parameters of r(C2sbnd C3), r(C2sbnd C6), ∠ C2C3N and ∠ C6C2C3, for s-trans-syn form were adjusted to the four observed rotational constants (B and C). The observed rotational constants for s-trans-(E) form were in good agreement with those calculated using the MP2/6-31 G (d, p) level of theory.
- Publication:
-
Journal of Molecular Spectroscopy
- Pub Date:
- July 2017
- DOI:
- 10.1016/j.jms.2017.04.003
- Bibcode:
- 2017JMoSp.337...17K
- Keywords:
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- Rotational spectroscopy;
- 2-Methyl-2-propenal oxime;
- Molecular structure;
- Dipole moments;
- Nuclear quadrupole coupling constants