Assembly of an interpenetrating three-dimensional mixed-valence Cu/Cu coordination polymer

A novel cyano-bridged three-dimensional mixed-valence Cu(II)/Cu(I) compound Cu₂(oxpn)]Cu(CN)₂]₂ (oxpn²⁻ = dianion of N,N^′-bis(3-aminopropyl)oxamide) has been synthesized and structurally characterized. Single crystals of 1 formed by diffusion of Cu₂(oxpn)Cl₂ and K₃Cr(CN)₅(NO)] in H₂O for two months. The structure of the title compound consists of threefold interpenetrating 3D frameworks. In each 3D network, oxamidato-bridged dimeric Cu₂(oxpn)]²⁺ units connect 1D polymeric Cu(CN)₂]⁻ anions giving rise to a 3D structure. Room temperature magnetic measurement shows the presence of strong magnetic coupling between the Cu(II) ions. Electronic paramagnetic resonance spectrum measurements show the transitions due to the excited triplet state.