Synthesis, crystal structures, and magnetic properties of three pairs of chiral cyanide-bridged Fe(III)–Cu(II) enantiomeric complexes

Abstract

With three trans-dicyanideiron(III) precursors K[Fe(L)(CN)₂] as building blocks (L = bpb²⁻, bpmb²⁻, bpdmb²⁻; bpb²⁻ = 1,2-bis(pyridine-2-carboxamido)-4,5-enzenate, bpmb²⁻ = 1,2-bis(pyridine-2-carboxamido)-4-methylbenzenate, bpdmb²⁻ = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethylbenzenate) and two chiral copper(II) compounds Cu[(S,S/R,R-dpen)₂](ClO₄)₂ (S,S/R,R-dpen = S,S/R,R-1,2-diphenylethylenediamine) as assembly segments, three pairs of cyanide-bridged enantiomers, {[(S,S/R,R-dpen)₂Cu(μ-CN)Fe(bpb)(CN)]ClO₄}₂ (1,2), {[(S,S/R,R-dpen)₂Cu(μ-CN)Fe(bpmb)(CN)]}ClO₄ (3,4), and {[(S,S/R,R-dpen)₂Cu(μ-CN)Fe(bpdmb)(CN)]}ClO₄ (5,6), have been obtained and characterized by elemental analysis, IR spectroscopy, and X-ray structure determination. Single X-ray diffraction analysis shows their similar binuclear structures, in which the cyanide-containing building blocks acting as a monodentate ligand through one of the two cyanide groups are linked to the five-coordinate Cu(II) ion, for which the four amine N complete the additional coordination positions. Investigation of magnetic properties of 1–6 reveals weak ferromagnetic magnetic exchange between the neighboring Fe(III) and Cu(II) ions through the bridging cyanide.

Graphical abstract

Keywords:

• Chiral
• Cyanide-bridged
• Crystal structure
• Magnetic property

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant number 21171107]; Natural Science Foundation of Shandong Province [grant number ZR2011BM008]; Science and Technology Project of High Education, Shandong Province [grant number J11LB09].