Crystal structure and magnetic properties of unusual 3D cyanide bridged {[Cu(bapa)]3[Cr(CN)6]2}n·6nH2O (bapa = bis(3-aminopropyl)amine) network

Abstract Blue crystals of {[Cu( bapa )] 3 [Cr(CN) 6 ] 2 } n ·6 n H 2 O ( bapa  = bis(3-aminopropyl)amine) have been prepared, characterized and investigated by IR spectroscopy, X-ray structural analysis and measurement of magnetic response. Its unusual 3D crystal structure is formed by infinite Cu(II)–Cr(III) antiparallel chains (turned by 38°), which are connected into the third direction by additive [Cu( bapa )] moieties. Each Cu(II) atoms are five-coordinated by three nitrogen atoms originating from one bapa molecule and by two nitrogen atoms from two bridging cyanido groups thus forming more or less distorted square pyramids. High number of ν (C N) absorption bands observed in the IR spectrum is in agreement with higher number of different bridging cyanido groups in the structure. Magnetic properties are governed by a strong ferromagnetic exchange interaction between Cu(II) and Cr(III) ions, the major exchange interaction was estimated as J Cr–Cu / k B  = 64.3 K with average g -factors g Cu  = 2.12 and g Cr  = 2.00.