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

Phenyl isocyanide has been chosen as a prototype to probe the pi-pi 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 pi-pi 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 pi-pi stacked structures, as well as practical proof of a biased interaction behavior of isocyanide-substituted aromatic molecules.

Automated summary

Phenyl isocyanide was chosen as a model to investigate the pi-pi interaction modulated by the -NC group. The rotational spectroscopic investigation and theoretical analyses revealed that the phenyl isocyanide dimer has a scissor-like configuration controlled by dispersive forces and pi-pi stacking. Additionally, this study provides the first evidence that mono-substitution of an -NC group on benzene can activate the meta position in forming noncovalent interactions.