London Dispersion Enables the Shortest Intermolecular Hydrocarbon H···H Contact

J Am Chem Soc. 2017 Jun 7;139(22):7428-7431. doi: 10.1021/jacs.7b01879. Epub 2017 May 23.

Abstract

Neutron diffraction of tri(3,5-tert-butylphenyl)methane at 20 K reveals an intermolecular C-H···H-C distance of only 1.566(5) Å, which is the shortest reported to date. The compound crystallizes as a C3-symmetric dimer in an unusual head-to-head fashion. Quantum chemical computations of the solid state at the HSE-3c level of theory reproduce the structure and the close contact well (1.555 Å at 0 K) and emphasize the significance of packing effects; the gas-phase dimer structure at the same level shows a 1.634 Å C-H···H-C distance. Intermolecular London dispersion interactions between contacting tert-butyl substituents surrounding the central contact deliver the decisive energetic contributions to enable this remarkable bonding situation.

Publication types

  • Research Support, Non-U.S. Gov't