Ternary complexes metal [Co(II), Ni(II), Cu(II) and Zn(II)] – ortho-iodohippurate (I-hip) – acyclovir. X-ray characterization of isostructural [(Co, Ni or Zn)(I-hip)2(ACV)(H2O)3] with stacking as a recognition factor

Four ternary metal – ortho-iodohippurate (I-hip) – acyclovir (ACV) complexes, [M(I-hip)2(ACV)(H2O)3] where M is Co(II) (1), Ni(II) (2), Cu (3) and Zn(II) (4) have been obtained by reaction between the corresponding binary complexes M(II)(I-hip)2·nH2O (5–8) and ACV. Three ternary complexes (M=Co, Ni and Zn) and the corresponding Zn(II) – ortho-iodohippurate binary derivative (8) have been structurally characterized by X-ray diffraction: The studies show these three ternary complexes are isostructural and present, in solid state, an interesting stacking between the nucleobase and the aryl ring of the hippurate moiety, which probably promotes the formation of ternary complexes. Moreover, the two different ligands interact between them by means of ancillary hydrogen bonds with water molecules coordinated to the metal ion. It must be mentioned that these two recognition factors, hydrogen bonds plus stacking, could explain the reason for the isostructurality of these ternary derivatives with so different three metal ions, with diverses trends in coordination numbers and geometries. In solid state, there are two enantiomeric molecules that are related by an inversion center as the crystal-building unit (as a translational motif) for the ternary complexes.