Insights into the gas‐phase structure and internal dynamics of diphenylsilane: A broadband rotational spectroscopy study

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 C2 point group symmetry with the C2 symmetry axis coinciding with the binertial axis of the molecule. Through the assignment of the main isotopologue as well as singly substituted heavy‐atom isotopologues, including 13C, 29Si, and 30Si, 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.