Low-dimensional compounds containing cyano groups. XVII. Crystal structure, spectroscopic, thermal and magnetic properties of [Cu( bmen) 2][Pt(CN) 4] ( bmen= N,N′-dimethylethylenediamine)

Abstract

The synthesis, structural analysis, spectroscopic studies, susceptibility and specific-heat measurements of {[Cu( bmen) 2][Pt(CN) 4]} n ( bmen= N, N′-dimethylethylenediamine) are presented. X-ray crystal-structure analysis revealed that the [Pt(CN) 4] 2− building blocks are combined with [Cu( bmen) 2] 2+ units to form a chain-like structure along the a axis. The Cu(II) atoms are hexacoordinated by four nitrogen atoms in the equatorial plane belonging to two molecules of bidentate bmen ligands with average Cu–N distance of 2.043(18) Å. The axial positions are occupied by two nitrogen atoms from bridging [Pt(CN) 4] 2− anions at a longer axial Cu–N distance of 2.490(4) Å. The compound is characterized by the presence of a weak antiferromagnetic exchange coupling J/k B =0.6 K. Despite the one-dimensional (1D) character of the structure, the analysis of the magnetic properties and specific heat at very low temperatures shows that [Cu( bmen) 2][Pt(CN) 4] behaves as a two-dimensional (2D) square-lattice Heisenberg magnet with weak interlayer coupling.