The benzyl radical C6H5CH2 has been obtained by gas phase pyrolysis of
two different precursors, benzyl bromide and dibenzyl, and studied in
an argon matrix at 12 K by IR spectroscopy. Similarly, the deuterosub
stituted benzyl radicals, C6H5CD2 and C6D5CH2, have been investigated.
The assignment of the IR bands of the benzyl radical and its deuteroa
nalogs to fundamental modes and a calculation of the valence force fie
ld have been performed. The obtained data give evidence of sp2 hybridi
zation of the methylene carbon atom and delocalization of the electron
density between the ring and the CH2 group, and are in good agreement
with the planar structure of the radical.