Antiferromagnetic Interactions in Copper(II) µ‐Oxalato Dinuclear Complexes: The Role of the Counterion. Issue 3 (18th December 2017)

• Record Type: Journal Article
• Authors: Julve, Miguel; Gleizes, Alain; Chamoreau, Lise Marie; Ruiz, Eliseo; Verdaguer, Michel
• Other Names: Le Guennic Boris guestEditor.; Chastanet Guillaume guestEditor.; Pillet Sébastien guestEditor.; Clérac Rodolphe guestEditor.
• Is Part Of: European journal of inorganic chemistry. Issue 3/4(2018)
• Page Start: 509
• Page End: 516
• Publication Date: 2017-12-18
• Subjects: Copper -- Oxalato -- Dinuclear complexes -- Magnetic properties -- Density functional calculations; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201700935
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : We report the preparation, crystal structure determination, magnetic properties and DFT calculations of five oxalato‐bridged dicopper(II) complexes of formula [Cu2 (bpy)2 (H2 O)2 (C2 O4 )](CF3 SO3 )2 (1 ), [Cu2 (bpy)2 (C2 O4 )](PF6 )2 (2 ), [Cu2 (bpy)2 (C2 O4 )](ClO4 )2 (3 ), [Cu2 (bpy)2 Cl2 (C2 O4 )]· H2 O (4 ) and [Cu2 (bpy)2 (NO2 )2 (C2 O4 )] (5 ) (bpy = 2, 2′‐bipyridine and C2 O4 2– = oxalate). Compounds1, 2, 4 and5 crystallize in the monoclinic system and3 crystallizes in the triclinic system. The oxalate ligands in1 –5 adopt the bis‐bidentate coordination mode and the two bpy molecules act as terminal ligands. The coordination of the counterions and the surroundings of the copper(II) ions differentiate the five compounds. The four nearest neighbours of copper(II) in1 –4 are roughly in the plane of the CuC2 O4 Cu framework, whereas they are in an almost perpendicular plane in5 . Using the isotropic HamiltonianH = – J S1 ·S2, whereS1 andS2 are the spin quantum operators for Cu1 and Cu2 ; J is –384 cm –1 for1, –392 cm –1 for2 and –387 cm –1 for3, slightly decreasing to –328 cm –1 for4 and falling to –14 cm –1 for5 . The influence of the anions on the magnetic properties of this family of compounds is explained by the changes in the overlap of the magnetic orbitals through the oxalate bridge. DFT calculations reproduce well the experimental values of J and provide an illustration of the magnetic orbitals. Abstract : Five dinuclear complexes [(bpy)Cu II (µ‐C2 O4 )Cu II (bpy)] 2+, 2X – (X – = CF3 SO3 –, 1 ; PF6 –, 2 ; ClO4 –, 3 ; Cl –, 4 ; NO2 –, 5 ) were prepared and characterized. Antiferromagnetic coupling J between the copper(II) ions depends greatly on the counterion, from ca. –388 cm –1 (1 ) to –328 cm –1 (4 ) and –14 cm –1 (5 ), due to magnetic‐orbital reversal. The counterion may prove to be not so innocent in molecular chemistry.