SYNTHESIS AND CHARACTERIZATION OF BISMUTH BROMIDE ARENE-PI COMPLEXES - X-RAY STRUCTURE OF BISMUTH(III) BROMIDE FLUORANTHENE-PARA-XYLENE (4/2/1)

A structural and spectroscopic investigation of a charge-transfer complex of bismuth(III) bromide with fluoranthene is reported. Charge-transfer spectra of some complexes formed by BiBr3 with a series of polycyclic benzenoid and non-benzenoid hydrocarbons were recorded. The charge-transfer band energies, Ec.t., and the ionization potentials of the electron donors are linearly correlated with a slope of one. A linear correlation is also observed for Ec.t. and the first –* singlet transition energies of the benzenoid hydrocarbons. The crystal and molecular structure of bismuth (III) bromide–fluoranthene–p-xylene (4/2/1) was determined: crystals are triclinic, space group P, with a= 9.812(6), b= 11.199(7), c= 12.861 (8)Å, = 71.59(6), = 80.28(6), = 74.38(7)°, Z= 2, and R= 0.0848. The structure is formed by tetrameric Bi4Br12 centrosymmetric units in which three bromine atoms bridge adjacent bismuths, which show distorted octahedral co-ordination having five sites occupied by bromines and the sixth by a benzene ring of the fluoranthene at longer distances.