Abstract The rotational spectrum of pyrrole-water was investigated before (Tubergen et al., 1993) In this work, we have applied a recently developed semiempirical tight-binding quantum chemistry program and DFT calculations to identify possible low energy conformers of the pyrrole-water complex which feature σ- and π-type hydrogen-bonding interactions. Using a cavity-based and two chirped pulse Fourier transform microwave spectrometers, we have measured and assigned all monosubstituted 13C isotopologues of pyrrole-water in their natural abundances. The 14N nuclear quadrupole hyperfine splittings and water tunneling doublets of these rarer isotopologues have also been observed and analyzed. Furthermore, we have carried out potential energy surface scans along possible paths of water large amplitude motions and identified all four previously proposed pyrrole-water geometries and correlated them to one global minimum and three transition states. The theoretical investigation together with the additional 13C experimental data allow one to confidently identify the ground state geometry and also estimate the water tunneling barrier.

中文翻译：

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吡咯-水复合物：其 13C 同位素体的多维大振幅动力学和旋转光谱

摘要 吡咯-水的旋转光谱在之前（Tubergen 等人，1993 年）进行了研究。在这项工作中，我们应用了最近开发的半经验紧束缚量子化学程序和 DFT 计算来识别吡咯-水的可能的低能量构象异构体。具有σ-和π-型氢键相互作用的复合物。使用基于腔的和两个啁啾脉冲傅里叶变换微波光谱仪，我们测量并分配了吡咯水的所有单取代 13C 同位素体的天然丰度。还观察和分析了这些稀有同位素的 14N 核四极杆超精细分裂和水隧穿双峰。此外，我们已经沿着水大幅度运动的可能路径进行了势能表面扫描，并确定了之前提出的所有四种吡咯 - 水几何形状，并将它们与一个全局最小值和三个过渡状态相关联。理论研究与额外的 13C 实验数据一起使人们能够自信地识别基态几何形状并估计水隧道障碍。