Conformational study of Co(II), Ni(II), and Cr(III) complexes of the edta-type: Crystal structure of 1D polymeric trans(O6)-Ba[Co(1,3-pddadp)] · 8H2O complex stabilized by infinite water tapes

MM calculations indicate that for the [M(1,3-pddadp)]n− system [where 1,3-pddadp represents the 1,3-propanediamine-N,N′-diacetate-N,N′-di-3-propionate ion, and M = Co(III), Cr(III), Rh(III), Ni(II), and Co(II)], the trans(O5O6) isomer is of the lowest energy. The least energetically favored trans(O)6 [Co(1,3-pddadp)]2− complex anion possesses unusual geometry and conformation of the β-alaninate rings, and forms, in a crystal, polymeric chains glued by infinite water tapes.