Benzene⋯acetylene: a structural investigation of the prototypical CH⋯π interaction

Abstract

The structure of a prototype CH···π system, benzene···acetylene, has been determined in the gas phase using Fourier-transform microwave spectroscopy. The spectrum is consistent with an effective C(6v) structure with an H···π distance of 2.4921(1) Å. The HCCH subunit likely tilts by ~5° from the benzene symmetry axis. The dipole moment was determined to be 0.438(11) D from Stark effect measurements. The observed intermolecular distance is longer than in similar benzene···HX complexes and than the distances observed in the benzene···HCCH cocrystal and predicted by many high level ab initio calculations; however, the experimentally estimated binding energy of 7.1(7) kJ mol(-1) is similar to previously studied benzene···HX complexes. Several additional sets of transitions were observed in the rotational spectrum, likely corresponding to excited states arising from low energy intermolecular vibrational modes of the dimer.

Toward Selection of Efficient Density Functionals for van der Waals Molecular Complexes: Comparative Study of C–H···π and N–H···π Interactions

“…The distance of ∼2.4 Å obtained using M06-2X is in excellent agreement with the recent experimental result of 2.492 Å. 1 The intermoiety distance (X−H···Bz CM ) obtained for Bz-Ac is shorter than that for Bz-Me. However, such distance for Bz-Am lies between the values for Bz-Ac and Bz-Me.…”

“… a Experimental or accurate computational data. b Taken from ref . c Taken from ref . d Taken from ref . e Taken from ref . f Taken from ref . …”

“…1 Nonbonding interactions of C−H or N−H bond with π-systems were often described as very weak conventional π-hydrogen bonds. 2−4 They are of broad interest to many forefront areas of chemistry, biology, and materials science.…”

Dynamic chiral self-recognition in aromatic dimers of styrene oxide revealed by rotational spectroscopy

“…For comparison purposes, complementary SAPT calculations on the 2-(4-fluorophenyl)oxirane dimer show that a small variation in the balance of dispersion and electrostatic contributions occurs with respect to SO, favouring electrostatics with an increase of 2-3% (see Supplementary Table 2). The effect of aromatic ring fluorination on CH-π interactions is more extensively discussed in a series of papers addressing the benzene-acetylene 63 , fluorobenzene-acetylene 64 and difluorobenzene-acetylene 65 complexes. We note that while double fluorination was shown to significantly alter the geometry of the benzene-acetylene complex, here the parallel-displaced geometry of the [0]RR dimer is Predicted rotational constants, dipole moment components and relative zero-point corrected electronic energies using the B3LYP-D3(BJ)/def2-TZVP level of theory; single-point energies ΔE CCSD(T) calculated using the DLPNO-CCSD(T) method; counterpoise-corrected interaction energies (E CP ); energy (kJ mol −1 ) decomposition obtained from an SAPT2+(3)/aug-cc-pVDZ calculation on all dimers using Psi4 (ref.…”

Study of CH/π Interactions in the Molecular Recognition between Acetyl Galactopyranoside and 6-substituted 2-Methoxypyridines and 2(1H)-Pyridones

“…The C 1 -H and C 6 -H bonds are in close proximity with the -C≡C-group of the pyridone receptor, with distances of 2.83 Å and 2.90 Å, respectively. It would be possible to have more than one type of CH/p interactions in this supramolecular complex [57]. The calculated interaction energies DE of the supramolecular complexes are shown in Table 3.…”