VARIABLE-TEMPERATURE X-RAY CRYSTALLOGRAPHIC AND MAGIC-ANGLE-SPINNING NMR SPECTRAL STUDIES ON HEXAETHYLBENZENE

At 353 K, the high-resolution C-13 solid-state NMR spectrum of hexaethylbenzene displays a coalescence phenomenon involving the well resolved sub-spectrum assigned to the methyl group carbon atoms. Thermodynamic parameters for the exchange(s) are reported. X-Ray crystallographic determinations at 150 and 353 K provide no evidence that complete ethyl group and/or arene rotations occur at 353 K, apparently contradicting the evidence of the variable-temperature magic-angle spinning (MAS) NMR study.