Low-dimensional compounds containing cyano groups. XIV. Crystal structure, spectroscopic, thermal and magnetic properties of [CuL2][Pt(CN)(4)] complexes (L = ethylenediamine or N,N-dimethylethylenediamine)

摘要

Violet crystals of [Cu(en)(2)][Pt(CN)(4)] and blue crystals of [Cu(dmen)(2)][Pt(CN)(4)] were crystallized from the water-methanol solution containing CuCl2 center dot 2H(2)O, ethylenediamine (en) or N,N-dimethylethylenediamine (dmen) and K-2[Pt(CN)(4)]center dot 3H(2)O. Both compounds were characterized using elemental analysis, infrared and UV-VIS spectroscopy, magnetic measurements, specific heat measurements and thermal analysis. X-ray structure analysis revealed chain-like structure in both compounds. The covalent chains are built of Cu(II) ions linked by [Pt(CN)(4)](2-) anions in the [111] and [101] direction, respectively. The Cu(II) atoms are hexacoordinated by four nitrogen atoms in the equatorial plane from two molecules of bidentate ligands L with average Cu N distance of 2.022(2) and 2.049(4) angstrom, respectively. Axial positions are occupied by two nitrogen atoms from bridging [Pt(CN)(4)](2-) anions at longer Cu-N distance of 2.537(2) and 2.600(5) angstrom, respectively. Both materials are characterized by the presence of weak anti ferromagnetic exchange coupling. Despite the one-dimensional (ID) character of the structure, the analysis of magnetic properties and specific heat at very low temperatures shows that [Cu(en)(2)][Pt(CN)(4)] behaves as two-dimensional (2D) spatially anisotropic square lattice Heisenberg magnet, while more pronounced influence of interlayer coupling is observed in [Cu(dmen)(2)][Pt(CN)(4)]. (C) 2006 Elsevier Inc. All rights reserved.