LIGANDS FOR APPLICATION IN COORDINATION CHEMISTRY - 3 DICARBOXYLIC-ACIDS

Three potential ligand molecules have been investigated. 6,6'-o-Phenylenedioxybis(2,2-dimethyl-4-oxahexanoic acid), C20H30O8 (I), has twofold crystallographic symmetry and adopts a conformation in which the two pendant carboxylic arms minimize any potential molecular cavity between them; zigzag polymeric chains are formed as a result of C=O...H-O hydrogen bonding about inversion centers. 2,2,9,9-Tetramethyl-4,7-dioxadecanedioic acid, C12H22O6 (II), also forms polymeric hydrogen-bonded chains involving the carboxylic acid moieties but differs from (I) in its molecular conformation. 2,2,6,6,10,10-Hexamethyl-4,8-dioxaundecanedioic acid, C15H28O6 (III), forms discrete rectangular-shaped centrosymmetric dimers in which any potential molecular cavity is minimized as a result of the close proximity of two of the pendant etheral arms.