Metal-Metal Bonded Diruthenium Unit Axial-Capped by Di-tert-butylphenolate:[Ru_2(O_2CCH_3)_2(t-Busal-R'py)_2]~-(t-Busal-R'py~2-= N-(R'-2-pyridyl)-2-oxido-3,5-di-tert-butylbenzylaminato;R' = H,4-Me,and 5-Me)

摘要

Three diruthenium compounds,[Na(18-crown-6)(thf)_2][Ru_2(O_2CCH_3)_2(t-Busalpy)_2](1),[K(18-crown-6)(thf)_2]-[Ru_2(O_2CCH_3)_2(t-Busal-4-Mepy)_2](2),and [K(18-crown-6)(thf)(H_2O)][K(18-crown-6)(thf)(MeO)][Ru_2(O_2CCH_3)_2-(t-Busal-5-Mepy)_2](3)(18-crown-6 = 1,4,7,10,13,16-hexaoxocyclooctadecane;18-crown-6-ether),have been synthesized by the ligand substitution reaction of Ru_2(O_2CCH_3)_4Cl with newly prepared tridentate bridging/chelating ligands,N-(2-pyridyl)-2-oxido-3,5-di-tert-butylbenzylaminato(t-Busalpy~(2-)),N-(4-methyl-2-pyridyl)-2-oxido-3,5-di-tert-butyl-benzylaminato(t-Busal-4-Mepy~(2-)),and N-(5-methyl-2-pyridyl)-2-oxido-3,5-di-tert-butylbenzylaminato(t-Busal-5-Mepy~(2-)),respectively,and isolated using [Na(18-crown-6)]~+ or [K(18-crown-6)]~+ as the counter cation.The structural features of the anionic parts are very similar to those of the previously synthesized family of [Ru_2(O_2CCH_3)_2-(5-Rsalpy)_2]~-(R = H,Me,Cl,Br,and NO_2);two acetate and two t-Busal-R'py~(2-)ligands are respectively located around the Ru_2 unit in a trans fashion,where the t-Busal-R'py~(2-)ligand acts as a tridentate ligand having both bridging and chelating characters to form the M-M bridging/axial-chelating mode.Their Ru-Ru bonded core with an electronic configuration of sigma~2pi~4delta~2(pi*delta*)(pi*delta*)~3 is axial-capped by the di-r-butylphenolate groups of the t-Busal-R'py~(2-)ligands,and experiences multi-redox properties:a one-electron reduction to Ru_2~(4+)and two one-electron oxidations to Ru_2~(6+)followed by Ru_2~(7+),in addition to t-Busal-R'py~(2-)ligand-centered redox.The strong electron-donating ability of the ?-butyl groups compared with the other R-groups leads to negative shifts of the redox potentials according to the Hammett law.