A new cyano-bridged one-dimensional polymeric mixed-valence Cu-II/Cu-I complex formed from reduction of a binuclear Cu-II complex with sodium cyanide

A new cyano-bridged polymeric mixed-valence Cu-II/Cu-I complex, [Cu(dien)(2)(CN)(2)Cu(CN)](n) (2) (dien = diethylenetriamine) has been prepared by the partial reduction of the OH-bridged binuclear complex [Cu-2(dien)(2)(OH)](ClO4)(3) (1) with sodium cyanide. The X-ray crystal structure shows that 1 is a polymeric, linear mixed-valence Cu-I/Cu-II complex and consists of a one-dimensional three-coordinated [Cu-I(CN)](n) chain, in which the Cu-I atoms are linked by two disordered CN bonding groups. The structure of each Cu-II atom consists of a square-pyramidal five-coordinate environment, in which the basal plane is formed by the three nitrogen atoms of the dien ligands and one carbon atom of the terminal cyanide group, and the apical position is occupied by the nitrogen atom of a bridging cyano ligand. This is the first example of one Cu-II centre coordinating with two different bonding types of the terminal Cu-II-CN and the bridging Cu-II-NC in a polymeric complex. The cryomagnetic behaviour has been investigated in the temperature range 4.2-300 K. There is a weak antiferromagnetic interaction between two intrachain copper(II) ions with J= -0.47 cm(-1). (C) 1997 Elsevier Science Ltd.