Graham Smith, D. Sagatys, R. C. Bott
1993
Citations
0
Influential Citations
12
Citations
Journal
Polyhedron
Abstract
Abstract Potassium antimony(III) citrate, {[K2Sb4(citrate)8(H2O)2} (1), and lithium antimony(III) citrate, {[LiSb(citrate)2(H2O)]·2H2O} (2), have been prepared and their structures determined by X-ray diffraction. With 1 each of the two independent centrosymmetric tetramers in the repeating unit of the complex comprises four independent antimony ions and eight citrate residues interlinked by two potassium centres [K—O range 2.62–3.06(1) A]. The difference between the two tetramers is that potassium is seven-coordinate in one and eight-coordinate in the other. The water molecules are coordinated to the potassium ions. Each antimony forms the usual distorted pseudo-trigonal bipyramidal four-coordinate complex through the α-hydroxy carboxylate oxygens of two citrate residues. A feature of the structure is the presence of three differently charged citrate species (1-, 2-, 3-), giving the formula {K2[Sb(C6H6O7)2]2[Sb(C6J7O7)(C6H5O7)]2(H2O)2}. The coordination about antimony in 2 is similar, but the lithium links the two citrate residues together via carboxyl and a hydroxyl oxygen from one ligand and a carboxyl oxygen from the second. A water completes the tetrahedral coordination sphere [mean LiO, 1.942(5) A]. Except for the four-coordination about lithium, the complex is similar to the analogous sodium complex {[NaSb(citrate)2(H2O)2]·H2O}.