Lanthanide complexes thermodynamic stabilities

Lanthanide hydride derivatives are commonly synthesized by hydrogenol-ysis of lanthanide alkyl complexes [212], In order to further exploit the thermodynamic stability of the Al-N bond dizsobutylaluminum hydride (DIBAH), a common cocatalyst in diene polymerization mixtures and well-established reducing agent in organic synthesis, was used in the hydrogenol-... 

DOTA is of particular interest as a BFC for radiolabeling of small BMs with yttrium and lanthanide isotopes. The macrocyclic framework is well organized so that it forms yttrium and indium complexes with high thermodynamic stability and kinetic inertness. The pXa values of the carboxylic groups are in the range 2-5. Lower pKa values result in less competition from protons, high stability of the metal complex, and minimum acid-assisted demetallation, even... 

The activation parameters for both acid-dependent and acid-independent pathways are given in Table 7.16. The low enthalpy of activation and a large negative entropy of activation for the self-dissociation pathway may well be due to a rate-determining step of slow distortion of the complex to give an active intermediate. The AH values for the acid-catalyzed pathway are much smaller than the values of lanthanide complexes with EDTA, CyDTA and MEDTA indicating lower thermodynamic stability of the K21DA complexes of lanthanides [73]. 

The thermodynamic stability of lanthanide complexes with inorganic ligands OH- and F increases slightly with increase in atomic number. The formation constants for MOH2+ and MF2+ formation... 

The second chapter deals with quantum chemical considerations, s, p, d and f orbitals, electronic configurations, Pauli s principle, spin-orbit coupling and levels, energy level diagrams, Hund s mles, Racah parameters, oxidation states, HSAB principle, coordination number, lanthanide contraction, interconfiguration fluctuations. This is followed by a chapter dealing with methods of determination of stability constants, stability constants of complexes, thermodynamic consideration, double-double effect, inclined w plot, applications of stability constant data. 

Kremer, C., Torres, J., Dominguezb, S., and Mederos, A. (2005) Structure and thermodynamic stability of lanthanide complexes with amino acids and peptides. Coordination Chemistry Reviews, 249, 567-590. 

Interest in the lanthanide complex species is centered currently largely in coordination number and stereochemistry, in thermodynamic stability and its interpretation, in the effects of the ligand on the properties of the lanthanide ion, and in practical applications. 

Larger differences between polarizable and effective models are to be expected, as suggested by Jorgensen et al [188], when dealing with solutions of di- and trivalent ions. A study of the effect of water polarizability on thermodynamic stability and kinetic lability of hydration complexes of a few lanthanide ions (Nd ", Sm, Yb " ) has been carried out by Kowall et al [189]. 

Structure and thermodynamic stability of lanthanide complexes with amino acids and peptides 05CCR(249)567. 

In this chapter, we deal with Gd " " complexes applied as Ti agents in MRI. In the first part of the chapter, we discuss the different relaxation mechanisms and how supramolecular approaches can be used to optimize the efficacy of Gd " "-based contrast agents. Nontoxicity is of prime importance for in vivo nse of metal chelates therefore, we also shortly assess some aspects related to their thermodynamic stability and kinetic inertness. We include a short infioduction to CEST (chemical exchange saturation transfer) agents, a new class of lanthanide-based MRI probes, and discnss how supramolecular systems, particularly liposomes, can be beneficial to decrease the sensitivity limit of CEST detection. In the second part of the chapter. 

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