Syntheses, characterization and stereochemistry of S- and R,S-hydrogenmalato dioxotungsten(VI)
- 化学化工－已发表论文 
Cis-dioxo hydrogemnalatc, tungstates(VI) Delta-Na-2[WO2(S-Hmal)(2)] . 4H(2)O 1, and Na-2[WO2(R,S-Hmal)(2)]2 (H(3)mal = malic acid) have been prepared from the reactions of excess S-malic acid and R,S-malic acid respectively, with sodium tungstate at ambient temperature. Both complexes were characterized by elemental analyses, conductivity measurement, optical rotation, UV-Vis, IR and NMR spectroscopy. Complex 1 was obtained with predetermined helical chirality at the metal center for a Delta-cis-configuration, which is established by single crystal X-ray diffraction. The crystal is orthorhombic, space roup P 2(1)2(1)2(1), with unit cell parameters: a = 7.9545(6), b = 10.7440(8), c = 21.045(2)Angstrom, V = 1798.6(2)Angstrom, Z = 4, D-c = 2.215 g cm(-3), F(000) = 1152, R=0.031, R-w = 0.034. Single crystal X-ray diffraction reveals that the cis-dioxo tungstate 1 is octahedrally coordinated by the S-malate through the deprotonated alpha-hydroxy and alpha-carboxylate groups, while the beta-carboxylic acid groups remain uncomplexed.