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Heterodinuclear LnNa Complexes with an Asymmetric Macrocyclic Compartmental Schiff Base
Author(s) -
Botta Mauro,
Casellato Umberto,
Scalco Cristina,
Tamburini Sergio,
Tomasin Patrizia,
Vigato Pietro A.,
Aime Silvio,
Barge Alessandro
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020902)8:17<3917::aid-chem3917>3.0.co;2-d
Subject(s) - chemistry , pentagonal bipyramidal molecular geometry , schiff base , isostructural , crystallography , lanthanide , crystal structure , molecule , coordination geometry , ligand (biochemistry) , ion , hydrogen bond , biochemistry , receptor , organic chemistry
Heterodinuclear lanthanide( III )–sodium( I ) complexes [LnNa(L)(Cl) 2 (CH 3 OH)] (Ln=La–Nd, Sm–Lu), where H 2 L is a [1+1] asymmetric compartmental macrocyclic ligand containing a N 3 O 2 Schiff base and a O 3 O 2 crown‐ether‐like coordination site, have been prepared and characterized by IR, 1 H, 13 C, and 23 Na NMR spectroscopy, mass spectrometry, and electron microscopy. In the solid state, the lanthanide( III ) ions coordinate the Schiff‐base N 3 O 2 site, and the sodium ion occupies the O 3 O 2 crownlike cavity, as shown by the X‐ray crystal structures of the Nd, Eu, Gd, and Yb derivatives. In these complexes, the lanthanide( III ) ion is coordinated by two chlorine atoms in the trans position and by three nitrogen and two negatively charged phenol oxygen atoms of the Schiff base, and the ion is heptacoordinated with a pentagonal bipyramidal geometry. The sodium ion is coordinated by three etheric oxygen atoms and the two phenolic oxygens that act as a bridge. A methanol molecule is also coordinated in the apical position of the resulting pentagonal pyramidal polyhedron. A detailed 1 H and 13 C NMR study was carried out in CD 3 OD for both diamagnetic and paramagnetic heterodinuclear complexes [LnNa(L)(Cl) 2 (CH 3 OH)]. The complexes are also isostructural in solution, and their structures parallel those found in the solid state. Moreover, some significative distances determined in the solid state and in solution are comparable. Finally, the potential use of these complexes as molecular probes for the selective recognition of specific metal ions has been tested. In particular, their ability to act as shift reagents and the selectivity of the O 3 O 2 site towards Li + , Ca 2+ , and K + were investigated by 23 Na NMR spectroscopy.