STRONTIUM IONS BRIDGED BY PYRAZINE-2,5-DICARBOXYLIC ACID AND WATER-MOLECULES MAKE A 3-DIMENSIONAL POLYMERIC STRUCTURE OF TRIAQUOMONO (MU-PYRAZINE-2,5-DICARBOXYLATO) STRONTIUM(II) DIHYDRATE CRYSTALS

riaquo(mu-pyrazine-2,5-dicarboxylato)strontium(II) dihydrate, SrC6H12N 2O9 crystallizes in the triclinic system, space group P (1) over bar, a = 6.238(1) Angstrom, b = 9.418(2) Angstrom, c = 10.591(2) Angstrom, alpha = 73.58(3)degrees, beta = 80.52(3)degrees, gamma = 75.01(3)degre es, Z = 2. The structure is polymeric. Strontium ions are bridged by p yrazine-2,5-dicarboxylic acid molecules which use both (N,O)-bonding m oieties (mean Sr-O = 2.567(3) Angstrom, mean Sr-N = 2.826(3) Angstrom) . In addition, the bridging is accomplished by two oxygen atoms from w ater molecules (mean Sr-O = 2.681(3) Angstrom) and bidentate oxygen at oms (Sr-O = 2.697(3) Angstrom) from a carboxylic group of a pyrazine-2 ,5-dicarboxylic acid molecule. As a result, a three-dimensional molecu lar framework is formed. The coordination around the Sr ion is ninefol d: seven oxygen and two nitrogen atoms make a distorted, monocapped sq uare antiprism. Two water molecules per unit cell are situated in the holes of this framework and participate in an extended hydrogen bond s cheme.