Trinuclear Cyanido-Bridged [Cr2Fe] Complexes: To Be or not to Be a Single-Molecule Magnet, a Matter of Straightness

Céline Pichon (1) , Nicolas Suaud (2) , Valentin Jubault (1) , Carine Duhayon (1) , Nathalie Guihéry (2) , Jean-Pascal Sutter (1)

1 LCC - Laboratoire de chimie de coordination
2 SEM - Systèmes étendus et magnétisme (LCPQ)

Trinuclear systems of formula [{Cr(LN3O2Ph)(CN)2}2M(H2LN3O2R)] (M=MnII and FeII, LN3O2R stands for pentadentate ligands) were prepared in order to assess the influence of the bending of the apical M−N≡C linkages on the magnetic anisotropy of the FeII derivatives and in turn on their Single-Molecule Magnet (SMM) behaviors. The cyanido-bridged [Cr2M] derivatives were obtained by assembling trans-dicyanido CrIII complex [Cr(LN3O2Ph)(CN)2]− and divalent pentagonal bipyramid complexes [MII(H2LN3O2R)]2+ with various R substituents (R=NH2, cyclohexyl, S,S-mandelic) imparting different steric demand to the central moiety of the complexes. A comparative examination of the structural and magnetic properties showed an obvious effect of the deviation from straightness of the M−N≡C alignment on the slow relaxation of the magnetization exhibited by the [Cr2Fe] complexes. Theoretical calculations have highlighted important effects of the bending of the apical C−N−Fe linkages on both the magnetic anisotropy of the FeII center and the exchange interactions with the CrIII units.

Mots clés: Ab initio calculations; Anisotropy; Magnetism; Pentagonal bipyramid; Single-molecule magnets

Domaines: Chimie théorique et/ou physique

Céline Pichon, Nicolas Suaud, Valentin Jubault, Carine Duhayon, Nathalie Guihéry, et al.. Trinuclear Cyanido-Bridged [Cr2Fe] Complexes: To Be or not to Be a Single-Molecule Magnet, a Matter of Straightness. Chemistry - A European Journal, 2021, 27 (62), pp.15484-15495. ⟨10.1002/chem.202102571⟩. ⟨hal-03424346⟩