Ferres Lynn, Truong Khai-Nghi, Stahl Wolfgang, Nguyen Ha Vinh Lam
Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52074, Aachen, Germany.
Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074, Aachen, Germany.
Chemphyschem. 2018 Jul 17;19(14):1781-1788. doi: 10.1002/cphc.201800115. Epub 2018 May 24.
To determine the structural properties of 2,3-dimethylanisole, a multidisciplinary approach was carried out where gas phase rotational spectroscopy recording a spectrum from 2 to 26.5 GHz using a pulsed molecular jet Fourier transform microwave spectrometer was combined with solid-state X-ray diffraction. Both methods revealed that only one conformer with a planar heavy-atom structure exists. In the solid state, the packing in the monoclinic space group is P2 /n with Z=4. In the gas phase spectrum, torsional splittings due to the internal rotations of two methyl groups attached to the phenyl ring were resolved and analyzed, providing an estimate of the barriers to methyl internal rotation of V =26.9047(5) and 518.7(12) cm for the methyl groups at the ortho- and meta-position, respectively. The coupling between the two internal rotations is modeled on a two-dimensional potential energy surface, which was obtained by quantum chemical calculations at the B3LYP/6-311++G(d,p) level of theory.
为了确定2,3 - 二甲基苯甲醚的结构性质，采用了多学科方法，将使用脉冲分子喷射傅里叶变换微波光谱仪记录2至26.5 GHz光谱的气相旋转光谱与固态X射线衍射相结合。两种方法均表明，仅存在一种具有平面重原子结构的构象异构体。在固态中，单斜空间群中的堆积为P2 /n，Z = 4。在气相光谱中，解析并分析了由于连接在苯环上的两个甲基的内旋转引起的扭转分裂，分别给出了邻位和间位甲基内旋转势垒的估计值，分别为V = 26.9047(5)和518.7(12) cm⁻¹。两个内旋转之间的耦合在二维势能面上进行建模，该势能面通过理论水平为B3LYP/6 - 311++G(d,p)的量子化学计算获得。
