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

Abstract

The beta-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-iPr(2)C(6)H(3); R = Me, Et) with (CuMes)(4) afforded the Cu(I) alumoxane [LAl(R)OCu center dot MesCu](2) (R = Me, 1; Et, 2). Using the aluminum-dihydroxide LAl(OH)(2) as the precursor, the dimeric [LAKOH)OCu center dot MesCu], (3) was isolated, bearing one reactive OH group on each Al center. When the reaction of LAKOH)2 with (CuMes)(4) was carried out at 70 degrees C, the dimeric octanuclear Cu(I) compound [LAl(OCu center dot MesCu)(2)](2) (4) was formed, where two residual Mes groups are located at the neighboring position on each of the two (OCu center dot MesCu)(2) squares. Compound 4 can be alternatively obtained by reacting 3 with 1 equiv of (CuMes)(4) to demonstrate the stepwise assembly of the Cu(I) alumoxanes.