NMR investigation of the lanthanide complexes with a 14-membered polyaza polyacetic macrocycle TETA. Another rare example of nonlabile lanthanide compounds

Desreux, Jean F.; Loncin, M. F.

doi:10.1021/ic00221a018

Cited by 38 publications

(19 citation statements)

References 2 publications

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“…Another successful application of NMR spectroscopy to conformational analysis is seen in the case of YbTETA chelate [62], The complex ion has a dodecahedral geometry in solution similar to that determined for the solid Na[Tb(TETA)] · 6H 2 0 · l/2NaCl [63]. The temperature dependence of the shift data were interpreted as reflecting an exchange between two dodecahedral arrangements with an energy of activation of ca.…”

Section: Stereochemistry and Optical Activitymentioning

confidence: 81%

Systematics of Lanthanide Coordination

Rizkalla

1993

Radiochimica Acta

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This article discusses the general trends of lanthanide coordination in solution. The bonding in these compounds is best described by an ionic model. Minor covalent interactions are inferred from spectral measurements; however, these probably involve the 5d or 6s rather than the 4/ orbitals. The enthalpy and entropy of these reactions are largely compensatory. Nevertheless, deviations are observed for systems involving strong metal-donor interactions such as the polyaminocarboxylates. The kinetics of complexation of these polyaminocarboxylates are interpreted in terms of a dissociative interchange mechanism. The rate-determining step probably involves the formation of a distorted LnY* complex (low AH* and negative AS*). The use of NMR and chiroptical methods to study the conformational preference and mode of coordination in these complexes are also discussed.

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Section: Stereochemistry and Optical Activitymentioning

confidence: 81%

Systematics of Lanthanide Coordination

Rizkalla

1993

Radiochimica Acta

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“…The coordination polyhedron of Tb 3+ is a strongly distorted dodecahedron, the TETA ligand has C 2 symmetry and its 14-membered macrocyclic ring exhibits a biangular {77} structure, a conformation which wraps efficiently about the Tb 3+ ion [347]. The solution structure of the Ln(TETA) − complexes has been studied by 1 H and 13 C NMR [211]. The conformational analysis was based on the previously published crystallographic structure of Tb(TETA) − [347].…”

Section: Tetamentioning

confidence: 99%

Structure, Dynamics, and Computational Studies of Lanthanide‐Based Contrast Agents

Peters

Djanashvili

Geraldes

et al. 2013

The Chemistry of Contrast Agents in Medical Magnetic Resonance Imaging

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“…Previous studies explained the fact that the dissociation rate of Ce(DOTA) 0 is much slower than that of Ce(TETA) 0 (1,4,8,11-tetraazacyclotetra-decane-N,N,NЉ,Nٞ-tetraacetic acid) (27). Despite the same cavity size (15-cycle), the acid-catalyzed rate of Ce (4) / dissociates about one order of magnitude faster than that of Ce(DTPA)-EAM (1,4,7-tris(carboxymethyl)-9,14-dioxo-1,4,7,10,13-pentaazacyclopentadecane) (15). This may be attributed to the decrease of one nitrogen donor and one carboxylic acid pendent arm compared to DTPA-EAM.…”

Section: The Displacement Of Ln 3/ Ions From Ln(edta)-bis(amide)mentioning

confidence: 99%

“…In recent years there has been growing interest in thermodynamic and kinetic studies of lanthanide complexes with macrocyclic polyaza-and polyazapolyoxapolycarboxylates because of their use as contrast agents in MRI (1,2), as aqueous NMR shift reagents (3,4), and as lanthanide selective reagents (5,6) for analytical applications. Several factors (7)(8)(9)(10)(11) are known to influence the stability and kinetics of lanthanide complexation with these ligands.…”

Section: Introductionmentioning

confidence: 99%