Structural Determination And Analysis Of Some New Schiff Base And Triangulo-Triruthenium Compounds
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Date
2011-01
Authors
Yap, Chin Sing
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Publisher
Universiti Sains Malaysia
Abstract
Eight Schiff base compounds were studied in this research. They crystallized out in the common space groups, i.e. four compounds are in monoclinic C2/c, and one each in monoclinic Cc, P21 and Pn and triclinic1P. One Schiff base compound exists in a zwitterion form. The structures of two Schiff base compounds are disordered. One Schiff base compound is a racemic twin crystal. Water solvent exists in the asymmetric unit of two Schiff base compounds. The Schiff base compounds all exist in an E configuration with respect to the N=C. The average N=C double bond value is 1.282 Å. Eighteen triangulo-triruthenium complexes were studied in this research. All of them crystallized out in the common space groups, i.e. seven compounds are in triclinic 1P, seven in monoclinic P21/c, two in monoclinic C2/c, and one each in orthorhombic Pbca and Pca21. The triangulo-triruthenium complex structures in four compounds are disordered. The asymmetric unit of eight compounds contains solvent molecules, e.g. water, dichloromethane or chloroform. All solvent molecules are disordered except for one of them. One triangulo-triruthenium compound is a racemic twin crystal and one triangulo-triruthenium compound is a pseudomerohedral twin crystal. In all triangulo-triruthenium complexes, the group 15 ligands occupy the equatorial position due to steric reaction. The effect of substitution results in significant differences in Ru—Ru bond lengths and carbonyl-ligands bond lengths and angles. The average three Ru—Ru bond lengths are 2.840 Å, 2.860 Å and 2.878 Å. The axial Ru—C bonds are longer than the equatorial Ru—C bonds. The average axial Ru—C bond lengths is 1.931 Å and the average equatorial Ru—C bond lengths is 1.892 Å. The bond length of equatorial Ru—C when connected to the same Ru atom with the monodantate ligand is the shortest bond in most of the molecules. The average of these Ru—C bonds is 1.882 Å. The equatorial Ru—C—O angles are close to linear whereas the axial Ru—C—O angles are slightly bent. The average equatorial Ru—C—O angles is 177.1° and the axial Ru—C—O angles is 173.4°.
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Keywords
Structural determination and analysis of some , new schiff base and triangulo-triruthenium compounds