Formation of the {Cu3II(μ3-OH)}5+ core in copper(II) carboxylate chemistry via use of di-2-pyridyl ketone oxime [(py)2CNOH] : [Cu3(OH)(O2CR)2{(py)2CNO}3] (R = Me, Ph)

Reactions of [Cu2(O2CMe)4(H2O)2] or Cu(O2CPh)2 · 2H2O with 2 or 1, respectively, molar equivalents of di-2-pyridyl ketone oxime, (py)2CNOH, in MeCN-based solvent mixtures yield complexes [Cu3II(μ3-OH)(O2CR)2{(py)2CNO}3] (1, R = Me; 2, R = Ph). Crystal structures of these compounds show similar triangles of CuII ions, centered by a triply bridging hydroxo ligand and with three edge-bridging oximate groups from the three 2.1110 (py)2CNO− ions. Preliminary variable-temperature magnetic susceptibility studies and EPR data at 4.2 K for 1 reveal an antiferromagnetically-coupled system showing antisymmetric exchange.

Graphical abstractThe use of di-2-pyridyl ketone oxime in reactions with CuII carboxylate sources has led to triangular complexes containing the {Cu3II(μ3-OH)}5+ core and possessing the shown, very rare inverse 9-metallacrown-3 motif created by the bridging oximate groups; the complexes have interesting magnetic and EPR properties.Figure optionsDownload full-size imageDownload as PowerPoint slide