Département de chimie moléculaire

A novel tetranuclear copper(II) complex [(L1)4Cu4(OH)4](ClO4)4.H2O (1) was synthesized from the self-assembly of copper(II) perchlorate and the ligand N-benzyl-1-(2-pyridyl)methaneimine (L1). Single-crystal x-ray diffraction studies revealed that complex 1 consists of a Cu4(OH)4 cubane core, where the four copper(II) centers are linked by $μ$3-hydroxo bridges. Each copper(II) ion is in a distorted square-pyramidal geometry. X-ray anal. also evidenced an unusual metal cation-$π$ interaction between the copper ions and Ph substituents of the ligand. Calcns. based on the d. functional theory method were used to quantify the strength of this metal-$π$ interaction, which appears as an important stabilizing parameter of the cubane core, possibly acting as a driving parameter in the self-aggregation process. In contrast, using the ligand N-phenethyl-1-(2-pyridyl)methaneimine (L2), which only differs from L1 by one methylene group, the same synthetic procedure led to a binuclear bis($μ$-hydroxo)copper(II) complex [(L2)2Cu2(OH)2(H2O)2](ClO4)2 (2) displaying intermol. $π$-$π$ interactions or, by a slight variation of the exptl. conditions, to a mononuclear complex [(L2)2Cu(OH2)](ClO4)2 (3). These complexes were studied by x-ray diffraction techniques. The magnetic properties of complexes 1 and 2 are reported and discussed. [on SciFinder(R)]