Synthesis and crystal structures of 4,4 '-bipyridinium and 2,2 '-bipyridinium pentachloro complexes containing the polynuclear anions [Bi2Cl10](4-) and [Bi4Cl20](8-)

The compounds 4,4'-bipyridinium(2+) pentachloro-bismuthate(III) (C10H8N2)Bi Cl5] and 2,2'-bipyridinium(2+) pentachloro-bismuthate (III) (2), [2,2'-(C10 H8N2)Bi2Cl10] have been obtained by reacting bismuthate oxide and 4,4'-bipy ridine or 2,2'-bipyridine in HCl acid medium. They have been characterized by single crystal X-ray analysis. (1) crystallizes in the triclinic space g roup P (1) over bar with a = 9.776(2), b = 11.009(3), 8.346(1) Angstrom, al pha = 101.58(2), beta = 98.63(2), and gamma = 112.86(2)4 (2) crystallizes i n the monoclinic space group P2(1)/c with a = 14.239(2), b = 14.226(2), c = 16.275(3) Angstrom, and beta = 110.15(2)degrees The crystal structure of ( 1) consists of 4,4'-bipyridinium(2+) cations interacting through hydrogen b onding with [Bi2Cl10](2-) dimers giving rise to endless double chains, whil e that of (2) is formed by 2,2'-bipyridinium(2+) cations and [Bi4Cl20](8-) tetramers extensively interacting through hydrogen bonding. The different p olynuclearity of the anions seems related to the different directions along which each cation can form hydrogen bond interactions.