Binuclear Metal Complexes. XXXIII. Synthesis, Structure, Spectra, and Magnetism of Binuclear Copper(II) Complexes with 2-[2-(Dialkylamino)ethylthio]ethanol

Binuclear copper(II) complexes with 2-[2-(dialkylamino)ethylthio]ethanol, Cu{R2N(CH2)2S(CH2)2O}X (abbreviated as Cu(R-nso)X, where R=CH3, C2H5, n-C3H7, n-C4H9; X=Br, Cl, NO3), were prepared and characterized by elemental analyses, infrared and electronic spectra and magnetic susceptibilities (80–300 K). They exhibit a band at 22–26×103 cm−1 characteristic of alkoxo-bridged structure. The magnetic data of Cu(n-C4H9-nso)Cl indicate that a strong antiferromagnetic interaction is operating between the copper ions. However, temperature dependence of magnetic susceptibilities of the other complexes do not obey the equation based on a binuclear structure. The crystal structure of Cu(CH3-nso)Br was determined by the single-crystal X-ray diffraction method. The crystals are monoclinic, space group P21/c, a=10.133(2), b=7.858(2), c=14.893(3) Å, β=118.8(1)°, and Z=2. The structure was solved by the heavy atom method and refined by the block-diagonal least-squares method to an R factor of 0.042. The structure consists of alkoxo-bridged binuclear units, Cu2(CH3-nso)2Br2. The coordination geometry of the copper ion is distorted square pyramid. Since the distances between the binuclear clusters are too long to give rise to an intercluster magnetic interaction, it is suggested that some structural change takes place at low temperature.