TY - JOUR
T1 - NMR studies of mixed-ligand lanthanide (III) complexes. Peculiarities of molecular structure, dynamics and paramagnetic properties for cerium subgroup chelates with crown ethers
AU - Babailov, Sergey P.
AU - Mainichev, Dmitry A.
PY - 2002
Y1 - 2002
N2 - The molecular structure, dynamics and paramagnetic properties of the complex cations [Ln(ptfa)2 (18-crown-6)]+ in deuterated toluene were studied for Ln = La, Ce, Pr and Nd. The activation enthalpy values of 68 ± 5, 55 ± 15 and 60 ± 13 kJ mol-1 for the 18-crown-6 conformational inversion processes for the complex cations of Ce, Pr and Nd, respectively, were obtained. Quantitative investigation of the lanthanide-induced chemical shifts shows a monotonic change of a spatial structure and magnetic susceptibility in comparison with the Bleaney predicted dependence. The free energy of molecular inversion activation for 18-crown-6 molecules in the complex cation [Ln(fod)2(18-crown-6)]+ is 74 ± 9 kJ mol-1 at 363 K, which is a little more than the value of the free energy of activation 64 ± 9 kJ mol-1 at 363 K in the complex cation [Ln(ptfa)2(18-crown-6)]+.
AB - The molecular structure, dynamics and paramagnetic properties of the complex cations [Ln(ptfa)2 (18-crown-6)]+ in deuterated toluene were studied for Ln = La, Ce, Pr and Nd. The activation enthalpy values of 68 ± 5, 55 ± 15 and 60 ± 13 kJ mol-1 for the 18-crown-6 conformational inversion processes for the complex cations of Ce, Pr and Nd, respectively, were obtained. Quantitative investigation of the lanthanide-induced chemical shifts shows a monotonic change of a spatial structure and magnetic susceptibility in comparison with the Bleaney predicted dependence. The free energy of molecular inversion activation for 18-crown-6 molecules in the complex cation [Ln(fod)2(18-crown-6)]+ is 74 ± 9 kJ mol-1 at 363 K, which is a little more than the value of the free energy of activation 64 ± 9 kJ mol-1 at 363 K in the complex cation [Ln(ptfa)2(18-crown-6)]+.
KW - Complexes
KW - Crown ethers
KW - Dynamic NMR
KW - Enthalpy of activation
KW - Lanthanides
KW - Molecular dynamics
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U2 - 10.1023/A:1021237718495
DO - 10.1023/A:1021237718495
M3 - Article
AN - SCOPUS:0347656726
VL - 43
SP - 187
EP - 193
JO - Journal of Inclusion Phenomena and Molecular Recognition in Chemistry
JF - Journal of Inclusion Phenomena and Molecular Recognition in Chemistry
SN - 1388-3127
IS - 3-4
ER -