Syntheses, structural determination, and binding studies of mononuclear nine-coordinate (EnH2)1.5[HoIII(Ttha)] · 4.5H2O and two dimensional unlimited network (EnH2)[HoIII(Egta)(H2O)]2 · 6H2O

Abstract

Two novel complexes, (EnH2)1.5[HoIII(Ttha)] · 4.5H2O (I) (En = ethylenediamine and H6Ttha = triethylenetetramine-N,N,N′,N″,N‴,N‴-hexaacetic acid) and (EnH2)[HoIII(Egta)(H2O)]2 · 6H2O (II) (H4Egta = ethyleneglycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid), were synthesized and their crystal structures were determined by single crystal X-ray diffraction techniques. Complex I has a nine-coordinate mononuclear structure with distorted tricapped trigonal prismatic conformation and crystallizes in the monoclinic crystal system with P2/n space group. The crystal data are as follows: a = 17.7541(18), b = 9.6810(10), c = 22.166(2) A, β = 118.913(2)°, and V = 3335.0(6) A3. Complex II has a mononuclear nine-coordinate structure with pseudo-monocapped square antiprismatic conformation and crystallizes in the monoclinic crystal system with P21/n space group. The crystal data are as follows: a = 12.978(8), b = 12.685(8), c = 14.905(9) A, β = 105.333(7)°, and V = 2366(2) A3. In I, there are two types of EnH22+ anions. They connect to [HoIII(Ttha)]3− by hydrogen bonds leading to the formation of 3D pore structure along z axis. In II, EnH22+ cation connects three adjacent [HoIII(Egta)(H2O)]− complex anions through hydrogen bonds, these hydrogen bonds lead to the formation of 2D network structure in [101] plane. The results showed that ligand structures play a crucial role in crystal and molecular structure of their complexes. In addition, the protonated (EnH22+) cations conjugating to [HoIII(Ttha)]3− and [HoIII(Egta)(H2O)]− complex anions are reviewed, which act as an important beginning for study of Ho(III) complexes conjugating with other various amino and heterocyclic biomolecule.