Scissor-like Face to Face π–π Stacking: A Surprising Preference Induced by the Isocyano Group in the Self-Assembled Dimer of Phenyl Isocyanide

Abstract

Phenyl isocyanide has been chosen as a prototype to probe the π–π interaction modulated by the −NC group, which has a chameleonic nature with two main resonance forms showing a triple bond and being carbenoid. The rotational spectroscopic investigation complemented with theoretical analyses indicates that the phenyl isocyanide dimer has a scissor-like configuration controlled by dispersive forces along with the formation of π–π stacking. This is the first rotational spectroscopic evidence, to the best of our knowledge, that the mono-substitution by an −NC group on benzene can activate the meta position in forming noncovalent interactions. This work also provides experimental evidence on the importance of substituent effects in modulating π–π stacked structures, as well as practical proof of a biased interaction behavior of isocyanide-substituted aromatic molecules.

Conformational equilibria and interaction preference in the complex of isoprene–maleic anhydride

“…40 The B2PLYP-D3(BJ)/def2-TZVP level of theory has been initially chosen because of its proven performance in predicting geometries of molecular complexes involving π interactions. 22 The counterpoise (CP) correction has been incorporated to minimize the basis-set superposition error (BSSE) at the same level. Harmonic frequency calculations were performed to confirm the real potential minima, providing zero-point vibrational energies.…”

“…21 Recent discoveries indicate that the mono-substitution of the isonitrile (-NC) group on the benzenic ring can lead the phenyl isocyanide dimer to be face-to-face-stacked with a scissor-like structure, characterized by a dominant p-p* interaction. 22 This is rationalized by the chameleonic nature of the -NC group which exhibits two main resonance forms as the carbenoid with a double bond or as the isoelectronic triple bond.…”

C···S Tetrel Bond Favored in the Phenyl Isothiocyanate-CO2 Complex: A Rotational Study

“…Investigations on the molecular complex of CO 2 have thus aimed at elucidating the interaction sites that govern the minimum-energy configurations of the monomers and identify the intermolecular forces at play . Particularly, high-resolution rotational spectroscopy complementary with quantum chemical calculation provides quantitative rather than just qualitative descriptions of the intrinsic factors affecting the structures and energetics of noncovalent bonded complexes . Its exceptional capability in spectral discrimination originates from its remarkable sensitivity to even subtle changes in mass distribution, leading to distinctive alterations in the patterns and fingerprints observed in rotational spectra. − …”

Insights into the Diels–Alder Reaction of Furan with Maleic Anhydride from Its Prereactive Intermediate

“…The vast majority of theoretical studies on the mechanism of DA cycloaddition have been confined to the TS directly connecting with reactants and products: the preferences on endo or exo TS could further lead to different reaction channels . However, the π–π* interactions remain challenging to be accurately described from theoretical calculations . Therefore, several theoretical levels would be generally chosen to compute the reaction coordinates, which often yield highly varying results .…”