One-dimensional azido-bridged chiral metal complexes with ferromagnetic or antiferromagnetic interactions: syntheses, structures, and magnetic studies

One-dimensional chiral copper(II) and manganese(II) coordination polymers with single asymmetric end-to-end (EE) azide bridges, [Cu(R-L)2(N3)]n(ClO4)n (1), [Cu(S-L)2 (N3)]n(ClO4)n (2), [Mn(R-L)2(N3)]n(ClO4)n (3), and [Mn(S-L)2(N3)]n(ClO4)n (4) (R-L or S-L = R- or S-pyridine-2-carbaldehyde-imine), have been synthesized, using azide ions as bridging groups and chiral Schiff bases as auxiliary ligands, and characterized. The crystal structure determination of complexes 1 and 2 reveals the formation of one-dimensional chiral chains, in which the central Cu(II) ion is six-coordinate in the form of an elongated octahedron. Complex 3 consists of chiral helical polymeric chains, in which the central Mn(II) has a slightly distorted octahedral geometry. They all crystallize in the chiral space group P2(1). Complexes 1 and 2 are rare examples that exhibit ferromagnetic interaction between copper(II) ions through the single end-to-end azido bridge. Fitting the susceptibility data for 1 using a 1D uniform chain model led to the parameters J = 0.70(3) cm(-1), g = 2.06(2), and zj' = 0.07(2) cm(-1). The magnetic studies on 3 and 4 show that there is weak antiferromagnetic coupling between the manganese(II) ions.