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-iPr2C6H3; R = Me, Et) with (CuMes)4 afforded the Cu­(I) alumoxane [LAl­(R)­OCu·MesCu]2 (R = Me, 1; Et, 2). Using the aluminum-dihydroxide
LAl­(OH)2 as the precursor, the dimeric [LAl­(OH)­OCu·MesCu]2 (3) 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 (4) was formed, where two residual Mes groups are located at the neighboring
position on each of the two (OCu·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.

将β-二亚胺基铝单氢氧化物（β-diketiminato aluminum-monohydroxide）与β-二亚胺基铝二氢氧化物分别与四聚体(CuMes)₄（其中Mes代表2,4,6-三甲基苯基，即2,4,6-Me₃C₆H₂）反应，以制备带有Al–O–Cu结构单元的一价铜（Cu(I)）配合物。所有上述配合物均通过元素分析、核磁共振波谱与单晶X射线衍射进行了结构表征。以铝单氢氧化物LAlR(OH)（其中L=HC[C(Me)N(Ar)]₂；Ar=2,6-二异丙基苯基，即2,6-iPr₂C₆H₃；R为甲基、乙基）与(CuMes)₄进行反应，得到了一价铜铝氧烷配合物[LAl(R)OCu·MesCu]₂（R为甲基时记为1，乙基时记为2）。以铝二氢氧化物LAl(OH)₂为反应前驱体，可分离得到二聚体配合物[LAl(OH)OCu·MesCu]₂（3），该配合物的每个铝中心均带有一个活性羟基基团。当LAl(OH)₂与(CuMes)₄在70℃下进行反应时，会生成八核一价铜二聚体配合物[LAl(OCu·MesCu)₂]₂（4），其中两个残留的Mes基团分别位于两个(OCu·MesCu)₂四元环的相邻位置上。配合物4也可通过将3与1当量的(CuMes)₄反应制得，这一结果验证了一价铜铝氧烷配合物的分步组装过程。