X-RAY DIFFRACTION STUDY OF THE CRYSTAL STRUCTURES OF PYRAZINE-2,5-DICARBOXYLIC ACID DIHYDRATE AND ITS MAGNESIUM COMPLEX
Title:
X-RAY DIFFRACTION STUDY OF THE CRYSTAL STRUCTURES OF PYRAZINE-2,5-DICARBOXYLIC ACID DIHYDRATE AND ITS MAGNESIUM COMPLEX
Author:
Ptasiewicz-Bąk, H. Leciejewicz, J.
Appeared in:
Journal of coordination chemistry
Paging:
Volume 44 (1998) nr. 3-4 pages 299-309
Year:
1998-07-01
Contents:
Pyrazine-2,5-dicarboxylic acid dihydrate, C4H2N2(COOH)2. 2H2O, is triclinic, Pl. a = 5.255(1)Å, b = 6.907(1) Å, c = 6.951(l)Å, a= 119.(3)°, β= 100.81(3)°, γ = 99.06(3)°, Z = 1. The structure is composed of molecular layers consisting of 2,5-pzdc and water molecules held by a system of hydrogen bonds. The interlayer spacing of 3.2 Å indicates interactions of the van der Waals type. Magnesium pyrazine-2,5-dicarboxylate hexahydrate, [Mg(H2O)6][C4H2N2(COO)2], is mono-clinic, P21/c, a = 8.016(l)Å, b = 6.858(1)Å, c= 11.278(1)Å, β = 99.52(3)°, Z = 2. Each magnesium atom is surrounded by six water molecules located at the apices of an almost regular octahedron with mean dMg-O = 2.060(1)Å. The 2,5-pzdc anions are planar with interatomic distances and angles characteristic for the pyrazine ring. A number of hydrogen bonds link the water molecules coordinated to Mg with carboxylic oxygens of the acid molecules. Their lengths range from 2.51 Å to 3.07 Å.
Journal description