Yun-Ho Chung, Ho-Hsiang Wei, Yi-Hung Liu, Gene-Hsiang Lee and Yu Wang
Three new µ-alkoxo-bridged dinuclear copper(II) complexes with µ-1-diethylaminopropan-2-olate, [Cu2{µ-Et2NCH2CH(Me)O }2X2] (X = N3- 1, NCO- 2 or NO2- 3), have been prepared and characterized by single-crystal X-ray diffraction analyses. The copper atoms have distorted square-planar environments bridged by two oxygen atoms of alkoxo groups. Magnetic susceptibility measurements in the temperature range 5–300 K indicated significant antiferromagnetic coupling for 3 and ferromagnetic coupling for 1 and 2 between the copper(II) atoms. The best least-squares-fitted coupling constants (2J) for 1, 2 and 3 were 81, 25 and -42 cm-1 respectively. By comparison to the known complex [Cu2{µ-Et2NCH2CH(Me)O }2(NCS)2] 4 (2J = -86.0 cm-1), a linear correlation between the magnetic coupling constants and the mean Cu–O–Cu angle (ϕ) with a crossover point at ϕ 97.3° from antiferromagnetic to ferromagnetic coupling is obtained. The catecholase activity of these copper(II) complexes for the oxidation of 3,5-di-tert-butylcatechol by O2 was studied and shown to be in the order 1 < 2 < 3.