A series of chiral cyanide-bridged Fe–Cu complexes: Synthesis, crystal structures and magnetic properties

Four trans-dicyanideiron(III)-containing building blocks and two chiral copper(II) compounds have been employed to assemble cyanide-bridged heterometallic complexes, resulting in six chiral cyanide-bridged Fe(III)–Cu(II) complexes, {[Cu(S,S/R,R-Chxn)2Fe(bpb)(CN)2]ClO4}2·xCH3OH·yH2O (1, 2), {[Cu(S,S/R/R-Chxn)2Fe(bpClb)(CN)2][Fe(bpClb)(CN)2]}·xCH3OH·yH2O (3, 4), {[Cu(R/R-Chxn)2Fe(bpdmb)(CN)2][Fe(bpdmb)(CN)2]}·4CH3OH (5) and {[Cu(R/R-Chxn)2][Fe(bpdBrb)(CN)2]2}·4CH3OH (6) (bpb2− = 1,2-bis(pyridine-2-carboxamido)-4,5-enzenate, bpClb2− = 1,2-bis(pyridine-2-carboxamido)-4-chlorobenzenate, bpdmb2− = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethylbenzenate, bpdBrb2− = 1,2-bis(pyridine-2-carboxamido)-4,5-dibromobenzenate, (S,S/R,R)-Chxn = (S,S/R,R)-1,2-diaminocyclohexane). The whole serials of complexes have been characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis shows that complexes 1–5 belong to cyanide-bridged cationic binuclear structure type with ClO4− or the anionic cyanide building block as balance anion for complexes 1, 2 and 3–5, respectively, while complex 6 can be structurally characterized as neutral sandwich-like trinuclear Fe2Cu entity. Investigation of the magnetic properties of complexes 1–6 reveals the weak antiferromagnetic coupling in complexes 1, 2 and the weak ferromagnetic interaction in complexes 3–6 between the neighboring Fe(III) and Cu(II) ions through the bridging cyanide group.

Graphical abstractFour trans-dicyanideiron(III)-containing building blocks and two chiral copper(II) compounds have been employed to assemble cyanide-bridged heterometallic complexes, resulting in six chiral cyanide-bridged Fe(III)–Cu(II) complexes, which have been characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Investigation over magnetic properties of complexes 1–6 reveals the weak antiferromagnetic or ferromagnetic magnetic coupling between the neighboring Fe(III) and Cu(II) ions through the bridging cyanide group in complexes 1, 2 and 3–6, respectively.Figure optionsDownload full-size imageDownload as PowerPoint slide