Synthesis and Characterization of Heterobimetallic Al–O–Cu Complexes toward Models for Heterogeneous Catalysts on Metal Oxide Surfaces

The β-diketiminato aluminum-monohydroxide and -dihydroxide were reacted with tetrameric (CuMes)₄ (Mes = 2,4,6-Me₃C₆H₂) to prepare Cu­(I) complexes bearing the Al–O–Cu moiety. All complexes are characterized by elemental analysis, nuclear magnetic resonance, and single-crystal X-ray diffraction. The reaction of aluminum–monohydroxide LAlR­(OH) (L = HC­[C­(Me)­N­(Ar)]₂; Ar = 2,6-<i>i</i>Pr₂C₆H₃; R = Me, Et) with (CuMes)₄ afforded the Cu­(I) alumoxane [LAl­(R)­OCu·MesCu]₂ (R = Me, <b>1</b>; Et, <b>2</b>). Using the aluminum-dihydroxide LAl­(OH)₂ as the precursor, the dimeric [LAl­(OH)­OCu·MesCu]₂ (<b>3</b>) was isolated, bearing one reactive OH group on each Al center. When the reaction of LAl­(OH)₂ with (CuMes)₄ was carried out at 70 °C, the dimeric octanuclear Cu­(I) compound [LAl­(OCu·MesCu)₂]₂ (<b>4</b>) was formed, where two residual Mes groups are located at the neighboring position on each of the two (OCu·MesCu)₂ squares. Compound <b>4</b> can be alternatively obtained by reacting <b>3</b> with 1 equiv of (CuMes)₄ to demonstrate the stepwise assembly of the Cu­(I) alumoxanes