A 1D coordination polymer built on asymmetric μ1,1,3-azide bridge: from unusual topology to magnetic properties and Cu(ii)/Cu(i) redox reversibility

Abstract

An azide-bridged Cu(II) one dimensional polymer was synthesized in a one pot reaction in the presence of ammonia. The refined crystal structure evidenced the unusual asymmetric μ_1,1,3 coordination mode of the azide ion leading to a {Cu(μ_1,1,3-N₃)(μ₁-N₃)(NH₃)_0.8(H₂O)_1.2}_n chain. The redox process of this complex was studied by cyclic voltammetry evidencing the Cu(II)/Cu(I) reversibility. Magnetic measurements were interpreted as a uniform antiferromagnetic chain (J = −15.2 cm⁻¹) holding rather strong inter-chain exchange (zJ′ = −2.8 cm⁻¹). Multireference difference dedicated configuration interaction (DDCI) calculations confirmed the non-negligible intensity of inter-chain interactions and evidenced a strong influence of the type of coordinated solvent, NH₃ or H₂O, on the nature and magnitude of the magnetic exchange.