Dispersion‐Bound Isolated Dimers in the Gas Phase: Observation of the Shortest Intermolecular CH⋅⋅⋅H−C Distance via Stimulated Raman Spectroscopy

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 CÀD vibration of appropriately deuterated (T t BuPM) 2 associated with an unusually short CÀD•••DÀC 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 S 6 -symmetric tail-to-tail arrangement.

Rovibronic signatures of molecular aggregation in the gas phase: subtle homochirality trends in the dimer, trimer and tetramer of benzyl alcohol

“…16 These Please do not adjust margins Please do not adjust margins assignments are very tentative due to the lack of conformational and size resolution. Such selectivity could be achieved for the further investigation of these weakly IR but more strongly Raman active bands with ionization loss (or gain) stimulated Raman spectroscopy, 49 in analogy to the IR/UV technique used here.…”

Boron-based octahedral dication experimentally detected: DFT surface confirms its availability

“…11 The final geometry optimizations of the obtained mono- and dications, in which Idip had been identified, also included the dispersion correction D3(BJ), suggested by Grimme, 25 because its use is justified by the possible interactions of the benzene rings. 26 On that basis, the formed monocationic 4-Idip- closo -1,2-P 2 B 4 Br 3 + ( 1a ), 1,6-Idip 2 - closo -1,2-P 2 B 4 Br 3 + ( 1b ) and 4-Idip- closo -1,2-As 2 B 4 Br 3 + ( 2 ) together with dicationic 3,5-Idip 2 - closo -1,2-P 2 B 4 Br 2 2+ ( 3 ) structural assemblies were subjected to structural studies using the above joint computational/experimental NMR approach (for the final products, see Fig. 1 and also Table 1).…”

London Dispersion Effects on the Stability of Heavy Tetrel Molecules

“…For example, Schreiner et al. have employed LD effects to stabilize long C−C bonds, [9,10] form highly ordered 2D lattices, [8] and also have experimentally determined LD interactions between certain ligand systems in the gas‐phase and in solution [11–19] . In a key advance, Grimme et al.…”