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(ClO ₄)_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 P2₁. 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.