Abstract
The reaction of terbium(III) nitrate penta-hydrate in aceto-nitrile with N,N'-bis-(2-hy-droxy-benz-yl)-N,N'-bis-(pyridin-2-ylmeth-yl)ethyl-enedi-amine (H2bbpen), previously deprotonated with tri-ethyl-amine, produced the mononuclear compound [N,N'-bis-(2-oxidobenzyl-κO)-N,N'-bis-(pyridin-2-ylmethyl-κN)ethylenedi-amine-κ(2) N,N'](nitrato-κ(2) O,O')terbium(III), [Tb(C28H28N4O2)(NO3)]. The mol-ecule lies on a twofold rotation axis and the Tb(III) ion is eight-coordinate with a slightly distorted dodeca-hedral coordination geometry. In the symmetry-unique part of the mol-ecule, the pyridine and benzene rings are both essentially planar and form a dihedral angle of 61.42 (7)°. In the mol-ecular structure, the N4O4 coordination environment is defined by the hexa-dentate bbpen ligand and the bidentate nitrate anion. In the crystal, a weak C-H⋯O hydrogen bond links mol-ecules into a two-dimensional network parallel to (001).
Highlights
The reaction of terbium(III) nitrate pentahydrate in acetonitrile with N,N0 bis(2-hydroxybenzyl)-N,N0 -bis(pyridin-2-ylmethyl)ethylenediamine (H2bbpen), previously deprotonated with triethylamine, produced the mononuclear compound [N,N0 -bis(2-oxidobenzyl-O)-N,N0 -bis(pyridin-2-ylmethyl-N)ethylenediamine-2N,N0 ](nitrato-2O,O0 )terbium(III), [Tb(C28H28N4O2)(NO3)]
N4O4 coordination environment is defined by the hexadentate bbpen ligand and the bidentate nitrate anion
Pyridyl and phenolate groups have been incorporated into these ligands because of their potential to mimic the coordination environments provided by the amino acids histidine and tyrosine, respectively (Hancock, 2013; Lenze et al, 2013)
Summary
As far as biological and biomedical applications are concerned, complexes of polydentate ligands with a range of metal ions in different oxidation states have been synthesized to model active sites of metalloproteins and to shed light on the consequences of heavy-metal chelation in living organisms, among many other applications (Colotti et al, 2013; Nurchi et al, 2013; Sears, 2013; Happe & Hemschemeier, 2014). E71, 65–68 doi:10.1107/S2056989014026826 research communications synthesized to provide detailed chemical information on the enzymatic activity of iron-tyrosinate proteins (Lanznaster et al, 2006) This ligand has been employed to prepare lanthanide(III), gallium(III) and indium(III) complexes for medicinal applications such as the development of new contrast agents for magnetic resonance imaging, MRI (Wong et al, 1995, 1996; Setyawati et al, 2000). The eightfold coordination pattern might be described as a distorted bicapped trigonal prism with O1 and N2 as the capping atoms This ignores the symmetry of the coordination, e.g. O1 and O1i would occupy different sites in the coordination polyhedron. The dodecahedral pattern incorporates the twofold symmetry and the distortion from the ideal geometry is minimal
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