Synthesis, crystal structure and properties of a novel cyano-bridged binuclear chromium(III) complex of a tetradentate Schiff base

The complex [Bu4N][{Cr(salen)CN)(2)CN].4H(2)O (H(2)salen = N,N'-ethylenebis(salicylideneiminato)) has been prepared by the reaction of [Cr(salen)(H2O)(2)]NO3 with NaCN. X-ray crystal structure analysis revealed the constituents to be binuclear anions, [{Cr(salen)CN)(2)CN](-), Bu4N+ cations and H2O molecules. The two Cr(III) atoms are bridged by a CN-ion in trans-mode. The geometry around each Cr(III) atom is approximately octahedral. The equatorial plane at each Cr(III) is composed of the N2O2 donor atoms of the tetradentate salen ligand. Axial sites are occupied by a terminal and a bridging CN group. The temperature dependence of the magnetic susceptibility indicates a weak antiferromagnetic interaction through the cyano bridge; an exchange parameter of -5.7 cm(-1) is close to those of other mu-CN chromium(III) complexes.