Vibrational spectra of tropylium tetrahaloborates [C7H7] [BX4] (X Br or I)

Abstract Raman and i.r. studies of the title compounds, which are salts of the planar D 7 h tropylium cation, provide complete sets of vibrational frequencies for the tetrahaloborate anions, including Raman data for [BI 4 ] − for which ν 1 ( a 1 ) = 169, ν 2 ( e ) = 83, ν 3 ( t 2 ) = 515 ( 11 B), 543 ( 10 B) and ν 4 ( t 2 ) = 117 cm −1 .