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Delicate Crystal Structure Changes Govern the Magnetic Properties of 1D Coordination Polymers Based on 3d Metal Carboxylates
Author(s) -
Gavrilenko Konstantin S.,
Cador Olivier,
Bernot Kevin,
Rosa Patrick,
Sessoli Roberta,
Golhen Stéphane,
Pavlishchuk Vitaly V.,
Ouahab Lahcène
Publication year - 2008
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/chem.200701316
Subject(s) - crystallography , monoclinic crystal system , antiferromagnetism , orthorhombic crystal system , magnetization , crystal structure , zigzag , single crystal , octahedron , materials science , ligand (biochemistry) , magnetic susceptibility , ferromagnetism , chemistry , coordination geometry , molecule , condensed matter physics , hydrogen bond , geometry , physics , magnetic field , biochemistry , mathematics , receptor , quantum mechanics , organic chemistry
Homo‐ and heterometallic 1D coordination polymers of transition metals (Co II , Mn II , Zn II ) have been synthesized by an in‐situ ligand generation route. Carboxylato‐based complexes [Co(PhCOO) 2 ] n ( 1 a , 1 b ), [Co( p‐ MePhCOO) 2 ] n ( 2 ), [ZnMn(PhCOO) 4 ] n ( 3 ), and [CoZn(PhCOO) 4 ] n ( 4 ) (PhCOOH=benzoic acid, p‐ MePhCOOH= p ‐methylbenzoic acid) have been characterized by chemical analysis, single‐crystal X‐ray diffraction, and magnetization measurements. The new complexes 2 and 3 crystallize in orthorhombic space groups Pnab and Pcab respectively. Their crystal structures consist of zigzag chains, with alternating M II centers in octahedral and tetrahedral positions, which are similar to those of 1 a and 1 b . Compound 4 crystallizes in monoclinic space group P 2 1 /c and comprises zigzag chains of M II ions in a tetrahedral coordination environment. Magnetic investigations reveal the existence of antiferromagnetic interactions between magnetic centers in the heterometallic complexes 3 and 4 , while ferromagnetic interactions operate in homometallic compounds ( 1 a , 1 b , and 2 ). Compound 1 b orders ferromagnetically at T C =3.7 K whereas 1 a does not show any magnetic ordering down to 330 mK and displays typical single‐chain magnet (SCM) behavior with slowing down of magnetization relaxation below 0.6 K. Single‐crystal measurements reveal that the system is easily magnetized in the chain direction for 1 a whereas the chain direction coincides with the hard magnetic axis in 1 b . Despite important similarities, small differences in the molecular and crystal structures of these two compounds lead to this dramatic change in properties.