Solution structure and dynamics of lanthanide complexes of the macrocyclic polyamino carboxylate DTPA-dien. NMR study and crystal structures of the lanthanum(III) and europium(III) complexes
- Univ. of California, Berkeley, CA (United States)
An 18-membered macrocyclic DTPA-bis(amide) ligand (DTPA = diethylenetriaminepentaacetic acid) containing a heteroatom in the amide link has been prepared via the condensation of DTPA-dianhydride and diethylenetriamine. The solution structures of the two isomeric pairs present in the Ln(III) complexes of DTPA-dien have been investigated by {sup 1}H NMR. The structures of the lanthanum(III) and europium(III) DTPA-dien complexes have been determined by X-ray analysis. [La(DTPA-dienH{sup +})H{sub 2}O]{sub 2}(CF{sub 3}SO{sub 3}{sup -}){sub 2}{center_dot}18H{sub 2}O (I) crystallizes as a carboxylate-bridged dimer about a center of inversion in the orthorhombic space group Pbca with a = 12.626(2) {angstrom}, b = 21.405(3) {angstrom}, c = 26.422(9) {angstrom}, and Z = 8. Each lanthanum ion is 11-coordinate with octadentate ligand coordination, an {eta}{sup 2} bridging carboxylate, and one water. [Eu(DTPA-dienH{sup +})]{sub 4}(CF{sub 3}SO{sub 3}{sup -}){sub 4}{center_dot}6NaCF{sub 3}SO{sub 3}{center_dot}20H{sub 2}O (II) crystallizes as a carboxylate-bridged tetramer with two crystallographically independent Eu(III) positions (Z = 8 for each) in the monoclinic space group C2/c: a = 30.94(1) {angstrom}, b = 23.456(3) {angstrom}, c = 22.611(4) {angstrom}, {beta} = 105.78(2){degrees}. The coordination geometries about Eu1 and Eu2 are nearly identical and are described as a nine-coordinate tricapped trigonal prism with octadentate ligand coordination plus an {eta}{sup 1} bridging carboxylate. The tendency to oligomerize is attributed to the constraints imposed by the macrocycle and the hydrogen bonding available with the link heteroatom. The structural differences between the two complexes are attributed to a difference in La(III) and Eu(III) ionic size.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 421014
- Journal Information:
- Inorganic Chemistry, Vol. 33, Issue 25; Other Information: PBD: 7 Dec 1994
- Country of Publication:
- United States
- Language:
- English
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