CHARGE-TRANSFER COMPLEXES AS RADIOLYTIC PRODUCTS FROM ALKYL HALIDES AND TOLUENE IN ALKANE MATRICES AT 77 DEGREES K

γ-Irradiated systems of C6H6 or C6H5CH3 in a matrix of CCl4 at 77°K exhibit absorption bands at ∼500 nm, not present for the same additives in a matrix of 3-methylpentane (3MP), which can be attributed to charge-transfer complexes Ar-Cl. When both C6H5CH3 and 2-C3H7Br are present in 3MP, bands at 500 and 675 nm appear which are not present with either additive alone. The 500-nm band is attributed to C6H5CH3·Br because it increased as C6H5CH3+ absorption decreased. The 675-nm band is attributed to C6H5CH3·C3H 7Br+ because its decay is coupled with increased absorption by C6H5CH3+. For 2-C3H7Br alone in 3MP, bands appear at 600, ∼400, 360, and 260 nm. By analogy with alkyl iodides in 3MP (ref 8), the dominant band in dilute solutions (400 nm) is attributed to PrBr+, and the strong band at high concentration (360 nm) to (PrBr)2+ from preexisting neutral dimer. Isothermal decay of these species enhances the 600-nm band, attributed to PrBr+ + Br- → PrBr·Br. The band at 260 nm behaved very differently and may be due to Pr•.