Chiral Resolution of a Mn 3+ Spin Crossover Complex
Résumé
Enantiopure Δ and Λ forms of the spin crossover Mn3+ chelate complex [Mn{5-OCF3-sal2(323)}]+ were prepared by co-crystallization with the (R,R) and (S,S) forms of the chiral spiroborate anion bis[1,1′-binaphthyl-2,2′-diolato]boron. The absolute structures of the enantiomers were established by X-ray crystallography at 100 K and at 293 K. The enantiomeric purity of the Δ and Λ forms in acetonitrile solution was confirmed by circular dichroism spectroscopy in the UV/Vis range. Both enantiomers show a gradual and incomplete S = 1 ↔ S = 2 thermal spin crossover in the solid state but persist mainly in the spin triplet form between 3–200 K and retain a high percentage of spin triplet character at room temperature
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