School of Chemistry, Monash University, 3800, Clayton, Victoria, Australia.
Gottfried-Wilhelm-Leibniz-Universität, Institut für Physikalische Chemie & Elektrochemie, Callinstraße 3a, 30167, Hannover, Germany.
Chemphyschem. 2021 Aug 18;22(16):1692-1697. doi: 10.1002/cphc.202100384. Epub 2021 Jul 7.
An accurate semi-experimental equilibrium structure of 8-hydroxyquinoline (8-HQ) has been determined combining experiment and theory. The cm-wave rotational spectrum of 8-HQ was recorded in a pulsed supersonic jet using broadband dual-path reflection and narrowband Fabry-Perot-type resonator Fourier-transform microwave spectrometers. Accurate rotational and quartic centrifugal distortion constants and N quadrupole coupling constants are determined. Rotational constants of all C, O and N singly substituted isotopologues in natural abundance and those of a chemically synthesized OD isotopologue were used to obtain geometric parameters for all the heavy atoms and the hydroxyl hydrogen from a number of structure determination models. Theoretical approaches allowed for the determination of a semi-experimental equilibrium structure, in which computed rovibrational and electronic corrections were utilized to convert vibrational ground state constants into equilibrium constants. Despite the molecule having only a horizontal plane of symmetry and possessing 11 individual heavy atoms, microwave spectroscopy has allowed for a reliable and accurate structure determination. A mass dependent, structure was determined and proved to be equally reliable by comparison with the B3LYP-D3(BJ)/aVTZ equilibrium structure.
结合实验和理论，确定了 8-羟基喹啉（8-HQ）的准确半经验平衡结构。在脉冲超音速射流中使用宽带双通道反射和窄带法布里-珀罗型谐振器傅里叶变换微波光谱仪记录了 8-HQ 的 cm 波旋转光谱。精确确定了旋转和四次离心畸变常数以及 N 四极耦合常数。利用所有 C、O 和 N 的天然丰度单取代同位素的旋转常数以及化学合成的 OD 同位素的旋转常数，从多个结构确定模型中获得所有重原子和羟基氢的几何参数。理论方法允许确定半经验平衡结构，其中计算的 rovibrational 和电子修正用于将振动基态常数转换为平衡常数。尽管该分子只有一个水平对称面，并且具有 11 个独立的重原子，但微波光谱学已经允许进行可靠和准确的结构确定。通过与 B3LYP-D3（BJ）/aVTZ 平衡结构进行比较，确定了一个质量相关的结构，证明其同样可靠。
