The crystal structures of bismuth halide complex salts. I. 2-Picolinium tetrabromobismuthate(III) and tetraiodobismuthate(III)

Abstract

2-Picolinium tetrabromobismuthate(III) and tetraiodobismuthate(III) are isomorphous. The anions in both structures show distorted octahedral packing of halogen atoms around bismuth, with two pairs of halogen bridges linking neighboring bismuth atoms. The two unshared bromine atoms are located at 2.63 ± 0.02 and 2.65 ± 0.02 A from Bi, and the Br-Bi-Br angle is 93.2 ± 0.6°. The corresponding values for the iodine structure are 2.87 ± 0.02 and 2.90 ± 0.02 A, and the I-Bi-I angle is 93.7 ± 0.5°. There is little evidence for the influence of the Bi "lone pair" upon the coordination around Bi in either structure. The various bond angles and distances in the halogen bridges are irregular, but the total Pauling bond order for the bismuth-halogen bonds is close to 3 for both structures.