3-氨基苯酚顺式和反式构象的精确偶极矩和四极耦合常数：绝对构象的测定
Precise dipole moments and quadrupole coupling constants of the cis and trans conformers of 3-aminophenol: Determination of the absolute conformation
摘要：
用傅里叶变换微波光谱法测定了顺、反3-氨基苯酚的转动常数和氮原子核四极耦合常数。我们研究了几个$J=2\leftarrow{}1$和$1\leftarrow{}0$超精细分辨旋转转换的两种构象。的过渡是适合一个刚性转子哈密顿包括核四极耦合占氮核。对于顺式-3-氨基苯酚，我们得到了转动常数A=3734.930 MHz，B=1823.2095 MHz，C=1226.493 MHz;对于反式-3-氨基苯酚，我们得到了转动常数A=3730.1676 MHz，B=1828.25774 MHz，C=1228.1948 MHz。利用斯塔克效应测量精确地确定了偶极矩，用于顺式-3-氨基苯酚的$μ_a=1.7735$ D、$μ_b=1.5195$ D和反式-3-氨基苯酚的$μ_a=0.5563$ D、$μ_b=0.5376$ D的几个超精细跃迁。然而，旋转常数和四极耦合常数不允许确定的绝对配置的两个构象，这个分配是直接的基础上的偶极矩。进行了高水平的\emph{ab initio}计算（B3 LYP/6- 31 G ^* 到MP2/aug-cc-pVTZ），提供了通过这些理论方法获得的大分子的转动常数和偶极矩的误差估计。
英文摘要：
The rotational constants and the nitrogen nuclear quadrupole coupling constants of cis-3-aminophenol and trans-3-aminophenol are determined using Fourier-transform microwave spectroscopy. We examine several $J=2\leftarrow{}1$ and $1\leftarrow{}0$ hyperfine-resolved rotational transitions for both conformers. The transitions are fit to a rigid rotor Hamiltonian including nuclear quadrupole coupling to account for the nitrogen nucleus. For cis-3-aminophenol we obtain rotational constants of A=3734.930 MHz, B=1823.2095 MHz, and C=1226.493 MHz, for trans-3-aminophenol of A=3730.1676 MHz, B=1828.25774 MHz, and C=1228.1948 MHz. The dipole moments are precisely determined using Stark effect measurements for several hyperfine transitions to $μ_a=1.7735$ D, $μ_b=1.5195$ D for cis-3-aminophenol and $μ_a=0.5563$ D, $μ_b=0.5376$ D for trans-3-aminophenol. Whereas the rotational constants and quadrupole coupling constants do not allow to determinate the absolute configuration of the two conformers, this assignment is straight-forward based on the dipole moments. High-level \emph{ab initio} calculations (B3LYP/6-31G^* to MP2/aug-cc-pVTZ) are performed providing error estimates of rotational constants and dipole moments obtained for large molecules by these theoretical methods.
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