Group 15 complexes with carboxylic acids—VI. Preparation and crystal structures of potassium antimony(III) citrate, {[K2Sb4(citrate)8(H2O)2]} and lithium antimony(III) citrate, {[LiSb(citrate)2(H2O)]·2H2O}

Triethyl-ammonium bis-(2-oxido-2,2-diphenyl-acetato-κO,O)anti-monate(III)

The coordination around the Sb atom in the title compound, (C(6)H(16)N)[Sb(C(14)H(10)O(3))(2)], is fourfold in a pseudo-trigonal-bipyramidal pattern in which one of the equatorial sites is occupied by the stereoactive lone pair of electrons. The four ligating atoms comprise the hydoxylate and carboxyl-ate O atoms from two independent benzilate ligands, each of which forms a five-membered chelating ring, spanning an axial and an equatorial site about the Sb atom. The hydroxy-late atoms occupy the two equatorial sites, and the carboxyl-ate atoms are in the pseudo-axial sites; the O-Sb-O angle is 147.72 (5)°. One carboxyl-ate group shows quite different bond lengths from those of the other group; one O atom is clearly the carbonyl atom and the other O atom the hydroxy-late atom. In the other ligand, there is less distinction in the C-O bonds. This is presumably related to the carbonyl O atom being the acceptor atom of a strong N-H⋯O hydrogen bond, which links the ammonium cation to the Sb complex anion.