The Conformational Landscape, Internal Rotation, and Structure of 1,3,5-Trisilapentane using Broadband Rotational Spectroscopy and Quantum Chemical Calculations
The Conformational Landscape, Internal Rotation, and Structure of 1,3,5-Trisilapentane using Broadband Rotational Spectroscopy and Quantum Chemical Calculations
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使用宽带旋转光谱和量子化学计算研究 1,3,5-三硅戊烷的构象景观、内部旋转和结构
DOI：
10.1021/acs.jpca.0c01100
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Grubbs, G. S.
中科院分区：
文献类型：
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作者：
Jabri, Atef;Marshall, Frank E.;Tonks, William Raymond;Brenner, Reid E.;Gillcrist, David J.;Wurrey, Charles J.;Kleiner, Isabelle;Guirgis, Gamil A.;Grubbs, G. S.
本文报道了在啁啾脉冲傅里叶变换微波光谱仪上观察到的1，3，5-三硅戊烷的转动光谱。在分配期间，在分子束中鉴定了分子的多种构象。先前对分子进行的量子化学计算表明，所识别的光谱对应于最低的三个计算的能量结构。这些结构具有C2（Conf.1）、C2 v（Conf.2）和C1（Conf.3）对称性，相对能量顺序为Conf.1 < Conf.3 < Conf.2，这与正戊烷和所有已知的硅取代正戊烷衍生物形成鲜明对比。这被认为是最有可能产生的伸长的Si-C键和硅原子的大小提供了theC 2andC 1结构相比，theC 2 v的空间位阻缓解。在theC 2 vandC 1构象，分裂的光谱由于内部旋转的− SiH 3端基的1，3，5-trisilapentane观察和确定。C2等效V3值为368.46（33）cm ~（-1），C1等效V3值分别为347.78（21）和360.18（88）cm ~（-1）。将这些屏障与类似物质进行比较，以帮助验证其准确性，并基于类似的分子甲硅烷基转子确定其准确性。
The rotational spectrum of 1,3,5-trisilapentane was observed on a chirped-pulse Fourier transform microwave spectrometer and is reported. During assignment, multiple conformations of the molecule were identified in the molecular beam. Prior quantum-chemical calculations performed on the molecule show that the identified spectra correspond to the lowest three calculated energetic structures. These structures are ofC2(Conf.1),C2v(Conf.2), andC1(Conf.3) symmetry, with relative energy ordering of Conf.1 < Conf.3 < Conf.2, which is in stark contrast ton-pentane and all known silicon-substitutedn-pentane derivatives. This is found to most likely arise from the elongation of the Si–C bond and the size of the silicon atoms providing for theC2andC1structures relieving steric hindrance in comparison to that of theC2v. In theC2vandC1conformers, splitting in the spectra due to internal rotation of the −SiH3end groups of 1,3,5-trisilapentane was observed and determined. TheC2vequivalentV3values are 368.46(33) cm–1, and theC1V3values are 347.78(21) and 360.18(88) cm–1, respectively. These barriers are compared to similar species in order to help verify their veracity and are determined to be accurate based on similar molecular silyl rotors.