Insights Into the Gas‐Phase Structure and Internal Dynamics of Diphenylsilane: A Broadband Rotational Spectroscopy Study

• Published in: Chemphyschem 2025-01, Vol.26 (2), p.e202400790-n/a
• Main Authors: Batra, Gayatri, Schnell, Melanie
• Format: Article
• Language: English
• Subjects: Broadband; Chemical bonds; Dynamic structural analysis; Fourier transforms; Frequency ranges; gas-phase structure; microwave spectroscopy; organosilicon molecules; rotational frequencies; Rotational spectra; Silicon; Solid phases; Symmetry; tunnelling
• ISSN: 1439-4235; 1439-7641; 1439-7641
• DOI: 10.1002/cphc.202400790

The rotational spectrum of diphenylsilane was investigated using chirped‐pulse Fourier transform microwave spectroscopy in the frequency range of 2–8 GHz. The lowest energy structure of diphenylsilane has C 2 ${_2 }$ point group symmetry with the C 2 ${_2 }$ symmetry axis coinciding with the b ${b}$ ‐inertial axis of the molecule. Through the assignment of the main isotopologue as well as singly substituted heavy‐atom isotopologues, including 13 ${^{13} }$ C, 29 ${^{29} }$ Si, and 30 ${^{30} }$ Si, we were able to obtain a comprehensive gas‐phase structure of diphenylsilane. The structure of diphenylsilane was compared with its oxygen analogue, diphenylether, including a discussion of the barrier height to the large‐amplitude motion of the phenyl rings. Furthermore, the structural comparison was extended to include a range of C−Si bond lengths and bond angles from other organosilicon molecules where the silicon atom is bonded to aliphatic and/or aromatic moieties. The structure of diphenylsilane could be determined from the rotational spectra of all its singly substituted heavy atom isotopologues. A comparison with its oxygen analogue diphenylether revealed some interesting differences in the internal dynamics as well as in the gas‐phase structure.