One-dimensional azido-bridged chiral copper(II) coordination polymers: Syntheses, structures and magnetic studies

Two new one-dimensional azido-bridged chiral copper(II) coordination polymers, [(μ-1,1,3-N3)2{Cu2(R-L)2(N3)2}]n (1) (R-L = R-2-(N-(2-hydroxybutyl)carbaldimino) pyridine) and [(μ-1,1,3-N3)2{Cu2(S-L)2(N3)2}]n (2) (S-L = S-2-(N-(2-hydroxybutyl)carbaldimino)pyridine) have been synthesized and structurally characterized. Complexes 1 and 2 crystallize in the monoclinic chiral space group P21. For 1, with a = 6.9565(17) Å, b = 20.675(5) Å, c = 9.859(2) Å, β = 105.944(5)° and Z = 2. In the case of compound 2, a = 6.9650(17) Å, b = 20.705(5) Å, c = 9.878(2) Å, β = 105.941(4)° and Z = 2. Both complexes consist of one-dimensional chiral structures in which the copper(II) ions with a distorted octahedral geometry are interlinked by the unusual μ-1,1,3 azido ligands. Circular dichroism spectra demonstrate that 1 and 2 are a pair of enantiomers. Their magnetic properties have been studied. Fitting of the susceptibility data for 1 and 2 using the Bleany–Bowers expression derived from the isotropic spin-exchange Hamiltonian H = −2JS1S2 leads to the parameters g = 2.21, J = −2.06 cm−1, zJ′ = −0.0309 cm−1 and R = 4.0 × 10−4.

Graphical abstractTwo new one-dimensional azido-bridged chiral copper(II) coordination polymers, [(μ-1,1,3-N3)2{Cu2(R-L)2(N3)2}]n (1) and [(μ-1,1,3-N3)2{Cu2(S-L)2(N3)2}]n (2) (L = 2-(N-(2-hydroxybutyl)carbaldimino)pyridine), have been synthesized and structurally characterized. Both crystal structures and circular dichroism spectra demonstrate that 1 and 2 are a pair of enantiomers. The magnetic studies on them reveal that there exist antiferromagnetic interactions between the copper(II) ions through μ-1,1,3-N3 azide bridges.Figure optionsDownload full-size imageDownload as PowerPoint slide