学生時代からtert-butyl基には妙に引かれるものがある。
J. Am. Chem. Soc., 2017, 139 (22), pp 7428–7431から
Neutron diffraction of tri(3,5-tert-butylphenyl)methaneat 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.
IntermolecularLondon dispersion interactionsbetween contacting tert-butyl substituents surrounding the central contact deliver the decisive energetic contributions to enable this remarkable bonding situation.