Cooperativity-Driven Reactivity of a Dinuclear Copper Dimethylglyoxime Complex.

In this report, we present the dinuclear copper(II) dimethylglyoxime (H 2 dmg) complex [Cu 2 (H 2 dmg)(Hdmg)(dmg)] + (1), which, in contrast to its mononuclear analogue [Cu(Hdmg) 2 ] (2), is subject to a cooperativity-driven hydrolysis. The combined Lewis acidity of both copper centers increases the electrophilicity of the carbon atom in the bridging μ 2 -O-N=C-group of H 2 dmg and thus, facilitates the nucleophilic attack of H 2 O. This hydrolysis yields butane-2,3-dione monoxime (3) and NH 2 OH that, depending on the solvent, is then either oxidized or reduced. In ethanol, NH 2 OH is reduced to NH 4 + , yielding acetaldehyde as the oxidation product. In contrast, in CH 3 CN, NH 2 OH is oxidized by Cu II to form N 2 O and [Cu(CH 3 CN) 4 ] + . Herein are presented the combined synthetic, theoretical, spectroscopic and spectrometric methods that indicate and establish the reaction pathway of this solvent-dependent reaction.