2ND-ORDER QUADRUPOLAR EFFECTS FOR DIRECTLY BONDED AND REMOTE C-13-BR-79/81 SPIN PAIRS IN HIGH-RESOLUTION C-13 NMR-SPECTRA OF SOLIDS

High-resolution solid-state C-13 NMR spectra of 1,4-dibromobenzene, 1,3,5-tribromobenzene, 1,2,4,5-tetrabromobenzene and hexabromobenzene (recorded at several different magnetic field strengths from 4.7-14.1 T) are reported. The bandshapes for C-13 nuclei directly bonded to Br-79/81 nuclei are characteristic multiplets arising from the effects of second-order quadrupolar interactions and both direct and indirect dipole-dipole interactions between C-13 and Br-79/81. Numerical simulations have been used to obtain data on dipolar coupling constants and/or anisotropies in indirect coupling. In these simulations, effects arising from interaction with the directly bonded Br-79/81 nucleus, intramolecular interactions with Br-79/81 nuclei in the ortho, meta and para positions relative to the C-13 nucleus, and intermolecular interactions with Br-79/81 nuclei in neighbouring molecules were considered. Spectra are also presented for a range of other organic solids containing bromine.