VARIABLE COORDINATION OF BARIUM IN ITS COMPLEXES - CRYSTAL-STRUCTURESOF BARIUM COMPOUNDS WITH 2-FURANCARBOXYLIC AND 3-FURANCARBOXYLIC ACIDS

Barium 2-Furancarboxylate (Ba 2-FA)Ba2.5C25H17O16, monoclinic, P2/c, a = 11.109(2) Angstrom, b = 17.813(4) Angstrom, c = 15.059(3) Angstrom, beta = 90.45(3)degrees, Z = 4. Barium 3-Furancarboxylate. (Ba 3-FA) B aC10H6O6, monoclinic, C2, a = 27.295(5) Angstrom, b = 3.957(1) Angstro m, c = 5.302(1) Angstrom, beta = 90.57(3)degrees, Z = 2. Both compound s are polymeric. Ba 2-FA is composed of cross-linked chains. In the fi rst coordination sphere of Ba the Ba-O-carboxyl and Ba-O-furan contact s are observed, Ba 3-FA chains are extended in the direction of c axis . In this structure the furan-ring oxygens are not involved in the coo rdination process, but they play a significant role in stabilization o f the crystal structure taking part as accepters in the intermolecular hydrogen bonds system.