Studies on the antitumor antimony(III) triaminocarboxylic complexonates. Crystal structures of NH 4[Sb(Hdtpa)]·H 20 and Na[Sb(Hdtpa)]·4 1/2 H 2O (dtpa = diethylenetriaminepentaacetic acid)

Abstract

The structures of NH 4[Sb(Hdtpa)]·H 2O(1) and Na[Sb(Hdtpa)]·4 1/2H 2O(2) were determined by single-crystal X-ray studies. In both complexes, the ligand dtpa, which is singly protonated, coordinates in a octadentate fashion involving the three nitrogen atoms and five of the carboxylate oxygen atoms of the ligand. The best description appears to be that of a ψ-monocapped square antiprism with N(1) being the capping atom and a lone electron pair located on the basal plane of the coordination polyhedron. Bond valence sums were calculated and are given for all Sb (III)-dtpa chelates available to date, and preliminary tests for antitumor activity as well as structure-activity relationships are also presented. Crystallographic data: 1, C 14H 23N 4O 10Sb·H 2O, monoclinic, P2 1/n, a=6. 867(1), b=14. 427(1), c=20.049(1) Å β=91.89(1)°, Z=4. A total of 3520 reflections was used in the refinement which converged to a final R value of 0. 0305; 2, C 14H 19N 3NaO 10Sb ·4 1/2 H 2O, triclinic, P1,a=7. 601(1), b=8.576(1), c=17, 688(4) Å, α=99.11(1), β= 97. 01(1), γ=97. 11(1)°, Z=2. A total of 3831 reflections was used in the refinement which converged to a final R value of 0. 0487.