Abstract: Thirty coordination polyhedra, reflecting the presence of a stereoactive lone electron pair, in the crystal structures of antimony(III) aminopolycarboxylic complexonates reported in the literature, have been revised. The presence of the lone pair has been acknowledged by including secondary bonded ligand atom(s) in the vicinity of the lone pair of each antimony(III). The resulted polyhedra are discussed in terms of their dihedral angles. In order to focus on the inherent coordination geometry of the central Sb(III) the vertices of the overall polyhedron are moved to the surface of a unit sphere. Inclusion of secondary bonding ligand atom(s) is supported by the valence bond calculations.

Key words: Secondary bonding, Bond valence sum, Coordination polyhedron, Antimony(III) complex, Aminopolycarboxylic acid, VSEPR theory