The microwave spectrum of 1-chloromethyl-1-fluorosilacyclopentane has been recorded for the first time using the chirped pulse, Fourier transform microwave technique. Quantum chemical calculations show the two lowest energy conformers as being a twist-trans and a gauche form with the gauche form previously being shown as having two separate conformations, a gauche+ (lower in energy) and gauche- (higher in energy) form. Analysis of the spectrum provided the observation of the twist-trans conformer only, with 253 and 85 transitions being assigned to the ³⁵Cl and ³⁷Cl isotopologues, respectively. $R$-branch, $a$- and $b$-type transitions were observed. The spectrum was fit to a Watson S-reduced Hamiltonian and consisted of rotational constants, quartic centrifugal distortion constants, and nuclear quadrupole coupling constants, including the determination of the off-diagonal nuclear quadrupole coupling constant, ${\chi }_{ab}$. Interpretation of the structure was provided using second moments and is found to have a similar ring structure to other known silacyclopentanes. Analysis of the ${\chi }_{zz}$ has been carried out and compared to other similar molecules. An investigation of the known quantum chemical energies of the gauche conformer reveals that the reported B3LYP energies do not align with the observed microwave results.

1-氯甲基-1-氟硅杂环戊烷的微波光谱首次使用啁啾脉冲、傅立叶变换微波技术记录下来。量子化学计算显示两种能量最低的构象异构体是扭曲反式和扭曲形式，之前显示的扭曲形式具有两种独立的构象，扭曲+（能量较低）和扭曲-（能量较高）形式。光谱分析仅提供了扭曲反式构象异构体的观察结果，其中 253 次和 85 次跃迁分别分配给³⁵ Cl 和³⁷ Cl 同位素体。$R$-分支，$A$- 和$b$型转变被观察到。该光谱适用于 Watson S-reduced Hamiltonian ，由旋转常数、四次离心畸变常数和核四极耦合常数组成，包括非对角线核四极耦合常数的确定，${\chi }_{Ab}$. 使用二阶矩提供结构的解释，并发现其具有与其他已知的硅杂环戊烷相似的环结构。的分析${\chi }_{zz}$已经进行并与其他类似分子进行了比较。对 gauche 构象异构体的已知量子化学能量的调查表明，报告的 B3LYP 能量与观察到的微波结果不一致。