Synthesis, crystal structure and chemical stability of bismuth(iii) complexed with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid (H8DOTMP)

Abstract

The potential use of the α-particle emitting compounds ^212/213Bi–DOTMP and ²¹²Pb–DOTMP in therapy of bone-associated cancers, and medical interest in bismuth compounds, motivated this study. Syntheses of the Bi(III) and Pb(II) complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid (H₈DOTMP) are reported. Extensive pH-stability was found for both complexes, in the pH range 0–13 for Bi–DOTMP and pH 4–14 for Pb–DOTMP. Furthermore, both complexes formed within 1 min in the pH range 6–10 at 10 µM metal-ion and 15 µM DOTMP. Single crystals of [NaBi(H₄DOTMP)] and polycrystalline [Bi(H₅O₂)(H₄DOTMP)] were formed and characterized by single crystal and powder X-ray diffraction methods, respectively. The structure of the anion was found in both salts to exhibit a square antiprismatic eight-coordination with a four-fold axis of symmetry.