Crystal structures, electron spin resonance, and thermogravimetric analysis of three mixed-valence copper cyanide polymers.

The crystal structures of three mixed-valence copper cyanide alkanolamine polymers are presented, together with thermogravimetric analysis (TGA) and electron spin resonance (ESR) data. In all three structures, a Cu II moiety on a crystallographic center of symmetry is coordinated by two alkanolamines and links two Cu I CN chains via cyanide bridging groups to form diperiodic sheets. The sheets are linked together by cuprophilic Cu I -Cu I interactions to form a three-dimensional network. In poly[bis(μ-3-aminopropanolato)tetra-μ-cyanido-dicopper(I)dicopper(II)], [Cu 4 (CN) 4 (C 3 H 8 NO) 2 ] n , 1, propanolamine bases have lost their hydroxyl H atoms and coordinate as chelates to two Cu II atoms to form a dimeric Cu II moiety bridged by the O atoms of the bases with Cu II atoms in square-planar coordination. The ESR spectrum is very broad, indicating exchange between the two Cu II centers. In poly[bis(2-aminopropanol)tetra-μ-cyanido-dicopper(I)copper(II)], [Cu 3 (CN) 4 (C 3 H 9 NO) 2 ] n , 2, and poly[bis(2-aminoethanol)tetra-μ-cyanido-dicopper(I)copper(II)], [Cu 3 (CN) 4 (CH 7 NO) 2 ] n , 3, a single Cu II atom links the Cu I CN chains together via CN bridges. The chelating alkanolamines are not ionized, and the OH groups form rather long bonds in the axial positions of the octahedrally coordinated Cu II atoms. The coordination geometries of Cu II in 2 and 3 are almost identical, except that the Cu-O distances are longer in 2 than in 3, which may explain their somewhat different ESR spectra. Thermal decomposition in 2 and 3, but not in 1, begins with the loss of HCN(g), and this can be correlated with the presence of OH protons on the ligands in 2 and 3, which are not present in 1.