Chain-like crystal structure and magnetic properties of [catena-bis(1,2- diaminoethane)copper(II)-μ-dicyano-argentate]-dicyanoargentate

• Published in: Inorganica Chimica Acta 1998-11, Vol.281 (2), p.134-140
• Main Authors: Černák, J., Chomič, J., Gravereau, P., Orendáčová, A., Orendáč, M., Kováč, J., Feher, A., Kappenstein, C.
• Format: Article
• Language: English
• Subjects: Copper; Crystal structures; Dicyanoargentate; Low-dimensional magnetic; X-ray analysis
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(98)00156-X

Cu(en) 2Ag 2(CN) 4 (en = 1,2-diaminoethane) crystallizes in the orthorhombic space group Pnnm with cell parameters a = 6.316(1), b = 9.018(2), c = 13.199(3) A ̊ , Z = 2 . The structure is formed of free linear [Ag(CN) 2] − anions and infinite cationic chains [-CU(en) 2NCAgCN-] −, containing paramagnetic copper atoms bridged by a second kind of linear dicyanoargentate species. The coordination geometry of the copper atoms corresponds to an elongated tetragonal bipyramid with two chelating en molecules in the equatorial positions and N-bonded bridging cyano groups in the axial positions. The Ag…Ag distances exhibit short value of 3.1580(5) Å. Weak bifurcated hydrogen bonds of the N(3)H(2)…N(2)(C(2))…H(2)N(3) type, symmetrical about twofold axis, are present (N(3)…N(2) 3.195(3) Å). These hydrogen bonds form two symmetrically related infinite 2D patterns in the xz plane at y = 0 and y = 1 2 connecting free dicyanoargentate anions and Cu(en) 2 2− cations. The phase identity between single crystal and bulk sample was evidence by powder X-ray diffractometry and Rietveld profile refinement. The study of magnetic properties by magnetization and specific heat measurements reveals that despite the chain structure the title compound may represent an S = 1 2 3 D magnetic system characterized by a low value of the exchange coupling constant. [ J/ k b] ⪡ 60 mK.