Synthesis and Relation Between Magnetism and Structure of the Binuclear Copper(II) Oxime Complex [Cu₂L₂(ClO₄)₂]·[Cu₂L₂(CH₃OH)₂](ClO₄)₂, Where HL = 1-(N,N-dimethyl-2-aminoethyl)-1-phenyl-2-oximopropane

The synthesis, structure, and properties of a new complex with empirical formula Cu2L2(CH3OH)(ClO4)2 are described, where HL = 1-(N,N-dimethyl-2-aminoethyl)-1-phenyl-2-oximopropane. From single-crystal X-ray diffraction data, the complex is shown to consist of [Cu2L2(ClO4)2]·[Cu 2L2(CH3OH)2]2+(ClO 4 -)2. The neutral species Cu2L2(ClO4)2 contains weakly coordinated perchlorato ligands (Cu-O = 2.551 (2) Å) while the ionic dimer [Cu2L2(CH3OH)2]2+ contains somewhat less weakly coordinated methanol (Cu-O = 2.341(3) Å). The Cu-Cu distances are 3.684 (1) and 3.582 (1) Å, respectively, in the neutral and ionic species. Each species has a pair of oxime N-O bridges between the two copper atoms to form a central, nearly planar, six-membered ring. The average angle in the six-membered ring is 120.0 (2)° in the neutral species and 119.5 (2)° in the cationic one, and the deviations of the individual ring angles from 120° can be ascribed to the relatively larger size of copper compared to the other atoms. The coordinated CH3OH and ClO4 - groups appear to have little effect. Thus, the six-membered rings may be considered as pseudoaromatic systems containing sp2 oxygen and nitrogen atoms, with the Pz orbital of each oxygen and nitrogen atom contributing an electron pair and the copper atoms each contributing one unpaired electron to make a total of ten π electrons per ring. The compound is diamagnetic in the range 4-300 K, as is expected for such a system. The magnetic exchange is therefore very large, |J| ≫ 1000 cm-1. Crystal data for [Cu2L2(ClO4)2]·[Cu 2L2(CH3OH)2]2+(ClO 4 -)2: Cu4Cl4O22N12C54H 80, black crystal, space group P1, Z = 1, a = 10.021 (4) Å, b = 10.090 (5) Å, c = 21.249 (8) Å, α = 91.13 (2)°, β = 109.36 (3)°, γ = 117.04 (3)°, V = 1768 Å3, R = 5.3% for 3745 reflections. © 1979 American Chemical Society