A new CuII-dinuclear paddlewheel complex. Structural and electronic properties

Crystal structure of tetra-kis-(μ-2-hy-droxy-3,5-di-isoprop-yl-benzoato)bis-[(dimethyl sulfoxide)copper(II)]

Metal complexes of 3,5-diiso-propyl-salicylate are reported to have anti-inflammatory and anti-convulsant activities. The title binuclear copper complex, [Cu2(C13H17O3)4(C2H6OS)2] or [Cu(II)2(3,5-DIPS)4(DMSO)2], contains two five-coordinate copper atoms that are bridged by four 3,5-diiso-propyl-salicylate ligands and capped by two axial dimethyl sulfoxide (DMSO) moieties. Each copper atom is attached to four oxygen atoms in an almost square-planar fashion, with the addition of a DMSO ligand in an apical position leading to a square-pyramidal arrangement. The hy-droxy group of the diiso-propyl-salicylate ligands participates in intra-molecular O-H⋯O hydrogen-bonding inter-actions.

N-heterocyclic carbene-mediated oxidation of copper(I) in an imidazolium ionic liquid

The aerobic oxidation of copper(I) to copper(II) was studied in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium acetate [BMIm][OAc]. Temperatures above 100 °C promote the deprotonation of the C2 atom of the imidazolium ring and the dissolution of CuCl. 1H and 13C NMR spectra indicate the formation of the N-heterocyclic carbene (NHC) complex [NHC] CuICl under inert conditions. Upon aerobic oxidation, air-stable blue-green crystals of [BMIm]2[CuII 2(OAc)4Cl2] precipitate in high yield and the NHC is recovered. X-ray diffraction on a single-crystal of the complex salt revealed a monoclinic structure with space group P21/n. The centrosymmetric dinuclear acetate complex [Cu2(OAc)4Cl2]2– has the paddle-wheel motif and is weakly paramagnetic.