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Selective Complexation of Uranium(III) over Cerium(III) and Neodymium(III) by 2,2′:6′,2′′‐Terpyridine − X‐ray Crystallographic Evidence for Uranium‐to‐Ligand π Back‐Bonding
Author(s) -
Berthet JeanClaude,
Rivière Christelle,
Miquel Yannick,
Nierlich Martine,
Madic Charles,
Ephritikhine Michel
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200206)2002:6<1439::aid-ejic1439>3.0.co;2-3
Subject(s) - chemistry , terpyridine , pyridine , lanthanide , crystallography , cerium , ligand (biochemistry) , bond length , crystal structure , inorganic chemistry , ion , medicinal chemistry , metal , organic chemistry , biochemistry , receptor
The addition of 2,2′:6′,2′′‐terpyridine (terpy) to MI 3 (M = Ce, Nd, U) in anhydrous pyridine led to the quantitative formation of the bis‐terpy complexes [MI 2 (terpy) 2 ]I [M = Ce ( 1 ) and Nd ( 2 )] and [MI 2 (terpy) 2 L]I [M = U and L = pyridine ( 3 ); M = Ce and L = H 2 O ( 4 )]. Conductometry measurements indicated that these complexes are 1:1 electrolytes in pyridine solution. 1 H NMR competition experiments showed that the terdentate ligand has a better affinity for U III than for Ce III or Nd III . The X‐ray crystal structures of solvates of 1 − 4 have been determined. The average U−N(terpy) bond lengths in 3 are 0.05 Å shorter than the mean Ce−N bond length in 4 ; the U−N(central pyridine) distances are shorter than the U−N(distal pyridines) distances in 3 , while the reverse order is found in the early lanthanide compounds. These differences could reflect the presence of a π back‐bonding interaction between the uranium atom and the terpy ligand. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)