McWhorter DA, Cupp SB, Lee CY, Pate BH
Department of Chemistry, University of Virginia, Charlottesville, VA, 22901
J Mol Spectrosc. 1999 Jan;193(1):150-158. doi: 10.1006/jmsp.1998.7711.
The pure rotational spectrum of the less stable conformer of methyl vinyl ether has been measured in an electric-resonance optothermal spectrometer. Analysis of the microwave spectrum shows that the less stable conformer is effectively planar with a low barrier between two gauche forms of the conformer. The rotational constants for the high-energy conformer, obtained from a least-squares fit to a threefold barrier internal rotation Hamiltonian are A = 39 192.490(26) MHz, B = 4527.5496(39) MHz, and C = 4181.2146(43) MHz. The threefold barrier to internal rotation is determined to be V3 = 427.516(71) cm-1. The dipole moment for the conformer has been measured using the Autler-Townes splitting of states in a strong, resonant microwave field. The dipole moment is µtot = 1.9(2) D [µa = 1.3(1) D, µb = 1.4(1) D]. The effectively planar structure of the conformer and the magnitude of the dipole moment are in good agreement with previous ab initio calculations. The experimentally determined threefold barrier to methyl rotation of the present study also agrees well with the value calculated from ab initio methods, 515 cm-1. Copyright 1999 Academic Press.
在一台电共振光热光谱仪中测量了甲基乙烯基醚较不稳定构象异构体的纯转动光谱。微波光谱分析表明，较不稳定的构象异构体实际上是平面的，在该构象异构体的两种gauche形式之间存在较低的势垒。通过对三重势垒内旋转哈密顿量进行最小二乘拟合得到的高能构象异构体的转动常数为：A = 39192.490(26) MHz，B = 4527.5496(39) MHz，C = 4181.2146(43) MHz。确定的内旋转三重势垒为V3 = 427.516(71) cm-1。使用强共振微波场中态的Autler-Townes分裂测量了该构象异构体的偶极矩。偶极矩为µtot = 1.9(2) D [µa = 1.3(1) D，µb = 1.4(1) D]。该构象异构体的有效平面结构和偶极矩大小与先前的从头算计算结果吻合良好。本研究中实验测定的甲基旋转三重势垒也与从头算方法计算的值515 cm-1吻合良好。版权所有1999年，学术出版社。
