ISSN:
1572-8854
Keywords:
Nedocromil sodium hydrates
;
sodium ion coordination
;
water molecule networks
;
carboxylate group conformation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract The crystal structure of one of the hydrated forms of nedocromil sodium, the heptahemihydrate, has been determined. Crystal data:a=26.687(5),b=29.479(8),c=6.394(3) Å, orthorhombic, space groupAba2,Z=8. This structure is compared with the previously determined structure of the trihydrate [Freer, A. A., Payling, D. W., and Suschitzky, J. L.,Acta Crystallogr. 1987,C43, 1900–1905]. The two structures differ in the molecular conformation of the nedocromil anion, the intensity of color, the coordination of the sodium ions, and the environment of the water molecules. In the heptahemihydrate two of the water molecules from dimers, whereas the remaining water molecules form a two-dimensional network consisting of a pentameric chain in one direction and an infinite chain in the other. From another viewpoint, 5 1/2 water molecules in the heptahemidydrate are present in the first coordination sphere of the sodium ions, whereas the remaining two water molecules are present as “lattice” water in the crystal.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01671084
