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Determination of the Nature of Exchange Interactions in the 3d–4f Magnetic Chain {[Cu(salen)Pr(hfac) 3 ] 2 (L)} n (L = 4,4′‐Bipyridine, Pyrazine)
Author(s) -
Pointillart Fabrice,
Bernot Kevin
Publication year - 2010
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/ejic.200901012
Subject(s) - chemistry , antiferromagnetism , crystallography , intramolecular force , diamagnetism , copper , crystal structure , ligand (biochemistry) , magnetic susceptibility , praseodymium , inorganic chemistry , stereochemistry , magnetic field , biochemistry , physics , receptor , organic chemistry , quantum mechanics , condensed matter physics
The reaction of copper(II)–praseodymium(III) 3d–4f precursors with nitrogenated ligands yields to a 3d–4f–4f–3d pseudo‐1D compound with the formula {[{Cu(salen)}{Pr(hfac) 3 } 2 (pyz)](H 2 O) 3 } (pyz = pyrazole). A “comparative method” was used to determine the nature of the magnetic interactions in this magnetic chain, by analysing the magnetic behaviour of diamagnetic or building‐block analogues. This method allows the estimation of the nature of all the magnetic interactions in the compound even in the presence of the orbitally degenerate Pr III ion. Two intramolecular exchange interactions [3d(Cu II )–4f(Pr III ) and 4f(Pr III )–4f(Pr III )] and one intermolecular exchange interaction [3d(Cu II )–3d(Cu II )] have been identified, and they have been found to be antiferromagnetic. The buildings blocks were obtained by reaction of Cu(salen) complexes with Pr(hfac) 3 · 3H 2 O, and the dinuclear [Cu(salen)Pr(hfac) 3 (H 2 O) n ] {hfac – = 1,1,1,5,5,5‐hexafluoroacetylacetonate, H 2 salen = N , N′ ‐ethane‐1,2‐diylbis(salicylidenamine), n = 0 or 1} or the heterotetranuclear {[{Cu(salen)}{Pr(hfac) 3 } 2 (bpy)](CHCl 3 ) 2 } compounds were formed. The diamagnetic analogues were obtained by substituting copper(II) by nickel(II). Evidence of a change of the crystal field around the Pr III ion as a result of the presence of a nitrogenated ligand in its coordination sphere is provided. The change in the crystal field leads to a different energy distribution of the Stark sublevels and allows the determination of the Cu II –Pr III interaction.