Ea. Piocos et al., RADICAL IONS OF ACETYLENE IN ZSM5 ZEOLITES - AN EPR AND THEORETICAL-STUDY, Journal of physical chemistry, 100(20), 1996, pp. 8408-8417
The cis-bent form of the acetylene radical anion (a(iso)(H) = 65 G) wa
s observed following radiolysis of acetylene-loaded HZSM5 but not NaZS
M5. The acetylene radical cation is not trapped by the matrix at 77 K
and undergoes ion-molecule reactions to form multimer ions, including
the benzene cation. Benzene is also formed by acid-catalyzed polymeriz
ation of acetylene on HZSM5. The evidence that acetylene (IP = 11.4 eV
) is ionized places a new lower limit on the range of ionizable specie
s in the radiolyzed zeolite. The energies, geometries, and hyperfine c
oupling constants were calculated for the acetylene, vinylidene, cyclo
butadiene and butatriene radical anions and radical cations, and the b
enzene radical cation, using different levels of theory, including gra
dient-corrected density functional theory.