The Conformational Landscape, Internal Rotation, and Structure of 1,3,5-Trisilapentane using Broadband Rotational Spectroscopy and Quantum Chemical Calculations


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 of C2 (Conf.1), C (Conf.2), and C1 (Conf.3) symmetry, with relative energy ordering of Conf.1 < Conf.3 < Conf.2, which is in stark contrast to n-pentane and all known silicon-substituted n-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 the C2 and C1 structures relieving steric hindrance in comparison to that of the C. In the C and C1 conformers, splitting in the spectra due to internal rotation of the -SiH3 end groups of 1,3,5-trisilapentane was observed and determined. The C equivalent V3 values are 368.46(33) cm-1, and the C1V3 values 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.



Research Center/Lab(s)

Center for High Performance Computing Research

International Standard Serial Number (ISSN)

1089-5639; 1520-5215

Document Type

Article - Journal

Document Version


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© 2020 NLM (Medline), All rights reserved.

Publication Date

14 May 2020

PubMed ID