Three Chiral Cyanide-Bridged Cr-Cu Complexes: Synthesis, Crystal Structures and Magnetic Properties

Two trans-dicyanidochromium(III)-containing building blocks and one chiral copper(II) compound have been employed to assemble cyanide-bridged heterometallic complexes, resulting in three chiral cyanide-bridged Cr(III)-Cu(II) complexes, [Cu(L1)2Cr(L3)(CN)2]ClO42 · CH3OH · H2O (1a, L1 = (S,S)-1,2-diaminocyclohexane, H2L3 =1,2-bis(pyridine- 2-carboxamido)benzene), [Cu(L2)2Cr(L2)(CN)2]ClO42 · CH3OH · H2O (1b, L2 = (R,R)-1,2-diaminocyclohexane) [Cu(L3)2Cr(L4)(CN)2][Cr(L4)(CN)2] · CH3OH · 2H2O (2), (H2L4 = 1,2-bis(pyridine-2-carboxamido)-4-chlorobenzene). All the three complexes have been characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single-crystal X-ray diffraction analysis shows that the two enantiomeric complexes 1a, 1b and the complex 2 belong to cyanide-bridged cationic binuclear structure type with ClO4 - or the anionic cyanide building block as balance anion for complexes 1a, 1b or 2, respectively. Investigation of the magnetic properties of the complexes 1a and 2 reveals the weak ferromagnetic coupling between the neighboring Cr(III) and Cu(II) ions through the bridging cyanide group.