Dirhodium Paddlewheel with Functionalized Carboxylate Bridges: New Building Block for Self-Assembly and Immobilization on Solid Support

详细信息    查看全文

• 作者：D. Krishna Kumar ; Alexander S. Filatov ; Margaret Napier ; Jinyu Sun ; Evgeny V. Dikarev ; Marina A. Petrukhina
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：April 16, 2012
• 年：2012
• 卷：51
• 期：8
• 页码：4855-4861
• 全文大小：339K
• 年卷期：v.51,no.8(April 16, 2012)
• ISSN：1520-510X

文摘

A new dirhodium(II,II) paddlewheel complex, [Rh₂(O₂CC₆H₄COOC₂H₅)₄] (1), has been synthesized using a predesigned functionalized carboxylate, namely, 4-(ethoxycarbonyl)benzoate. The target product has been crystallized from the acetone solution and structurally characterized as a bis-acetone adduct, [Rh₂(O₂CC₆H₄COOC₂H₅)₄(OCMe₂)₂]路C₆H₁₄ (2). By utilizing the ability of dangling ester groups to coordinate to open axial ends of neighboring dirhodium units, 1 can self-assemble to form 2D networks upon crystallization from solutions of noncoordinating solvents such as chlorobenzene and chloroform. The resulting [Rh₂(O₂CC₆H₄COOC₂H₅)₄]路2C₆H₅Cl (3) and [Rh₂(O₂CC₆H₄COOC₂H₅)₄]路2CHCl₃ (4) products have microporous solid state structures with the pores filled with the corresponding disordered solvent molecules. Notably, 3 and 4 represent unique examples of 2D extended frameworks based on dirhodium tetracarboxylate paddlewheel units devoid of any exogenous ligands. In solution, the dangling ends of carboxylate bridges of 1 have been successfully utilized for condensation reaction with the selected solid support, benzylamine-functionalized polystyrene, allowing successful heterogenization of dirhodium units through the equatorial covalent attachment to the substrate. The resulting solid product was tested as a catalyst in the cyclopropanation reaction of styrene with methyl phenyldiazoacetate to show good yields and diastereoselectivity.