Syntheses, structural determination, and binding studies of binuclear eight-coordinate (enH2)[GdIII 2(pdta)2(H2O)2] · 8H2O and mononuclear nine-coordinate (enH2)[GdIII(egta)(H2O)]2 · 6H2O

Abstract

The (enH2)[GdIII 2(pdta)2(H2O)2] · 8H2O (1) (en = ethylenediamine and H4pdta = propylenediamine-N, N, N′, N′-tetraacetic acid) and (enH2)[GdIII(egta)(H2O)]2 · 6H2O (2) (H4egta = ethyleneglycol-bis-(2-aminoethylether)-N, N, N′, N′-tetraacetic acid) complexes were synthesized and characterized by infrared spectrum, thermal analysis, and single-crystal X-ray diffraction. The complex (enH2)[GdIII 2(pdta)2(H2O)2] · 8H2O has a binuclear eight-coordinate structure with pseudo square antiprism and crystallizes in the monoclinic crystal system with C2/c space group. Through a carboxylate bridge, an infinite 1-D zigzag polymeric binuclear [GdIII 2(pdta)2(H2O)2]2− complex anion is formed. All infinite zigzag polymeric complex anions link through hydrogen bonds, yielding a layer structure. (enH2)[GdIII(egta)(H2O)]2 · 6H2O has a mononuclear nine-coordinate structure with pseudo monocapped square antiprism and crystallizes in the monoclinic crystal system with P21/n space group. Each enH2 2+ cation, through hydrogen bonds, connects two adjacent [GdIII(egta)(H2O)]− complex anions.