title: Dirhodium paddlewheel with functionalized carboxylate bridges: new building block for self-assembly and immobilization on solid support.
abstract: A new dirhodium(II,II) paddlewheel complex, [Rh(2)(O(2)CC(6)H(4)COOC(2)H(5))(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, [Rh(2)(O(2)CC(6)H(4)COOC(2)H(5))(4)(OCMe(2))(2)]·C(6)H(14) (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 [Rh(2)(O(2)CC(6)H(4)COOC(2)H(5))(4)]·2C(6)H(5)Cl (3) and [Rh(2)(O(2)CC(6)H(4)COOC(2)H(5))(4)]·2CHCl(3) (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.
authors.affiliation: Department of Chemistry, University at Albany, 1400 Washington Avenue, Albany, New York 12222, USA.
authors.forename: D Krishna
authors.initials: DK
authors.lastname: Kumar
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Filatov
authors.forename: Margaret
authors.initials: M
authors.lastname: Napier
authors.forename: Jinyu
authors.initials: J
authors.lastname: Sun
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Dikarev
authors.forename: Marina A
authors.initials: MA
authors.lastname: Petrukhina