Cyanido-Bridged Fe(III)−Mn(III) Heterobimetallic Materials Built From Mn(III) Schiff Base Complexes and Di- or Tri-Cyanido Fe(III) Precursors

Tapas Senapati (1) , Céline Pichon (1) , Rodica Ababei (1, 2) , Corine Mathonière (2) , Rodolphe Clérac (3, 1)

1 CRPP - Centre de recherches Paul Pascal
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
3 Matériaux Moléculaires Magnétiques

The reaction of [FeIIIL(CN)3]− (L being bpca = bis(2- pyridylcarbonyl)amidate, pcq = 8-(pyridine 2-carboxamido)quinoline) or [FeIII(bpb)(CN)2]− (bpb = 1,2-bis(pyridine-2-carboxamido)benzenate) ferric complexes with MnIII salen type complexes afforded seven new bimetallic cyanido-bridged Mn(III)−Fe(III) systems: [Fe(pcq)(CN)3Mn(saltmen)- (CH3OH)]*CH3OH (1) , [Fe(bpca)(CN)3Mn(3-MeO- salen)- (OH2)]*CH3OH*H2O (2), [Fe(bpca)(CN)3Mn(salpen)] (3), [Fe(bpca)- (CN)3Mn(saltmen)] (4), [Fe(bpca)(CN)3Mn(5-Me-saltmen)]*2CHCl3 (5), [Fe(pcq)(CN)3Mn(5-Me-saltmen)]*2CH3OH*0.75H2O (6), and [Fe(bpb)- (CN)2Mn(saltmen)]*2CH3OH (7) (with saltmen2− = N,N′-(1,1,2,2- tetramethylethylene)bis(salicylideneiminato) dianion, salpen2− = N,N′- propylenebis(salicylideneiminato) dianion, salen2− = N,N′-ethylenebis- (salicylideneiminato) dianion). Single crystal X-ray diffraction studies were carried out for all these compounds indicating that compounds 1 and 2 are discrete dinuclear [Fe(III)−CN−Mn(III)] complexes while systems 3−7 are heterometallic chains with {−NC−Fe(III)−CN−Mn(III)} repeating units. These chains are connected through π−π and short contact interactions to form extended supramolecular networks. Investigation of the magnetic properties revealed the occurrence of antiferromagnetic Mn(III)***Fe(III) interactions in 1−4 while ferromagnetic Mn(III)***Fe(III) interactions were detected in 5−7. The nature of these Mn(III)***Fe(III) magnetic interactions mediated by a CN bridge appeared to be dependent on the Schiff base substituent. The packing is also strongly affected by the nature of the substituent and the presence of solvent molecules, resulting in additional antiferromagnetic interdinuclear/interchain interactions. Thus the crystal packing and the supramolecular interactions induce different magnetic properties for these systems. The dinuclear complexes 1 and 2, which possess a paramagnetic ST = 3/2 ground state, interact antiferromagnetically in their crystal packing. At high temperature, the complexes 3−7 exhibit a one-dimensional magnetic behavior, but at low temperature their magnetic properties are modulated by the supramolecular arrangement: a three-dimensional antiferromagnetic order with a metamagnetic behavior is observed for 3, 4, and 7, and Single-Chain Magnet properties are detected for 5 and 6.

Mots clés: Molecular magnetic materials

Domaines: Matériaux

Tapas Senapati, Céline Pichon, Rodica Ababei, Corine Mathonière, Rodolphe Clérac. Cyanido-Bridged Fe(III)−Mn(III) Heterobimetallic Materials Built From Mn(III) Schiff Base Complexes and Di- or Tri-Cyanido Fe(III) Precursors. Inorganic Chemistry, 2012, 51 (6), pp.3796-3812. ⟨10.1021/ic2027708⟩. ⟨hal-00681411⟩