Thermally-Accessible Lattice Strain and Local Pseudo Jahn-Teller Distor- tion in Various Dimensional Cu-M Bimetallic Cyanide-Bridged Assem- blies

Cocrystals of one-dimensional cyanide-bridged Cu-Cr or Cu-Co bimetallic assemblies and mononuclear Cu complexes, [Cu(chxn)2]3[M(CN)6]2·4H2O (chxn = trans-cyclohexane-(1R,2R)-diamine; M = Cr for 1 and Co for 2), and two-dimensional cyanide-bridged Cu-Fe bimetallic assembly, [Cu(N-Eten)2]3[Fe(CN)6]2·4H2O (N-Eten = Nethylethylenediamine) (3), were prepared and characterized structurally. Crystal structures were determined at 263 and 100 K for 1 and 2, while at 299 and 100 K for 3. Thermally-accessible lattice strain resulted in decreasing cell volume of 1.66, 1.06, and 4.1 % for 1-3, respectively. Large thermally-accessible structural change but small pseudo Jahn-Teller elongation at constant temperature could be found in both the long chain of the ladder structure for 3 and the monocuclear Cu moieties for 1 and 2. In addition, novel mixing of ferromagnetic and antiferromagnetic interactions at low temperature was observed for 3. The correlations between dimensionality of cyanide-bridges and thermally-accessible structural changes distortion associated with Jahn-Teller distortion are also discussed by comparing with several known systems.