Structure of catena–(2–Amino–1,3,4–Thiadiazolium, 2–Amino–1,3,4–Thiadiazole bis(mu–Iodo)–di–Iodo–Bismuth(III))

[(C2H4N3S) (C2H3N3S) BiI4]infinity; [(HL) (L) BiI4]infinity (L = 2-amino-1,3,4-thiadiazole), M(r) = 919.86, monoclinic, P 1 2(1)/a 1, a = 7.622(1), b = 18.977(2), c = 12.821(1)angstrom, beta = 102.77(1)-degrees, final R = 0.033. The crystals consist of HL+ cations, neutral L molecules and polymeric [BiI4]infinity- anions built up of edge-sharing [BiI6]3- octahedra, with Bi-I(bridging) distances in the range 3.320(1)-3.057(1) angstrom and Bi-I(terminal) distances in the range 2.917(1)-2.929(1)angstrom. The H-1 and C-13 spectra in DMSO-d6 solution are used in conjunction with the X-Ray structural results to establish the preferred protonation site of the thiadiazole ring.