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)(2)Fe(bpb)(CN)(2)]ClO4}(2)center dot xCH(3)OH center dot yH(2)O (1, 2), {[Cu(S,S/R/R-Chxn)(2)Fe(hpClb)(CN)(2)][Fe(bpClb)(CN)(2)]}center dot xCH(3)OH center dot yH(2)O (3, 4), {[Cu(R/R-Chxn)(2) Fe(bpdmh)(CN)(2)][Fe(bpdmb)(CN)(2)]}center dot 4CH(3)OH (5) and {[Cu(R/R-Chxn)(2)][Fe(bpdBrb)(CN)(2)](2)}center dot 4CH(3)OH (6) (bpb(2-) = 1,2-bis(pyridine-2-carboxamido)-4,5-enzenate, bpClb(2-) = 1,2-bis(pyridine-2-carboxamido)-4-chlorobenzenate, bpdmb(2-) = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethylbenzenate, bpdBrb(2-) = 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. (C) 2015 Elsevier Ltd. All rights reserved.