Dispersion-Bound Isolated Dimers in the Gas Phase: Observation of the Shortest Intermolecular CH⋅⋅⋅H-C Distance via Stimulated Raman Spectroscopy.
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ABSTRACT: The triphenylmethane and all-meta tert-butyl triphenylmethane dimers, (TPM)2 and (T t BuPM)2 , respectively, were studied with ionization loss stimulated Raman spectroscopy in molecular beam experiments to resolve structure sensitive vibrations. This answers the question whether the recently reported linear head-to-head arrangement in (T t BuPM)2 results from crystal packing or prevails also in the gas phase, and therefore must result from extraordinarily strong London dispersion (LD) interactions. Our study clearly demonstrates that the head-to-head arrangement is maintained even under isolated molecular beam conditions in the absence of crystal packing effects. The central Raman-active aliphatic C-D vibration of appropriately deuterated (T t BuPM)2 associated with an unusually short C-D⋅⋅⋅D-C distance exhibits a strong blue-shift compared to the undisturbed case. As the LD stabilizing tert-butyl groups are absent in (TPM)2 , it displays an approximately S6 -symmetric tail-to-tail arrangement.
SUBMITTER: Maue D
PROVIDER: S-EPMC8252503 | biostudies-literature |
REPOSITORIES: biostudies-literature
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