Solid-state 13C and 2H nuclear magnetic resonance studies of the benzene–hexafluorobenzene complex

Abstract

Solid-state ¹³C NMR employing magic-angle spinning (MAS) and cross polarisation (CP) is used in a qualitative investigation of the extent of charge-transfer and polarisation contributions to the intermolecular binding in the C₆H₆–C₆F₆ complex. The principal values of the ¹³C chemical shift tensor for both benzene and hexafluorobenzene components are found to be very similar to those for the pure components, suggesting little electron redistribution upon complex formation. ²H NMR is used to extend previous work on the molecular dynamics of this system. It is found that the benzene ring ‘wobbles’ with an amplitude that varies with temperature, in addition to performing rapid reorientations about the local C₆ axis. Finally, the ¹³C–¹⁹F dipolar coupling constant determined from the ¹³C NMR experiments gives the C—F bond length in C₆H₆–C₆F₆ as 0.133 ± 0.002 nm.