Noninnocence of Indigo: Dehydroindigo Anions as Bridging Electron-Donor Ligands in Diruthenium Complexes

作者：Mondal Prasenjit; Chatterjee Madhumita; Paretzki Alexa; Beyer Katharina; Kaim Wolfgang^*; Lahiri Goutam Kumar^*

来源：Inorganic Chemistry, 2016, 55(6): 3105-3116.

DOI：10.1021/acs.inorgchem.6b00038

Complexes of singly or doubly deprotonated indigo (H(2)Ind) with one or two [Ru(pap)(2)](2+) fragments (pap = 2-phenyl-azopyridine) have been characterized experimentally [molecular structure, voltammetry, electron paramagnetic resonance (EPR), and UV-vis-near-IR spectroelectrochemistry] and by-time-dependent density functional theory calculations. The compound [Ru(pap)(2)(HInd(-))]ClO4 ([1]ClO4) was found to contain an intramolecular NHO hydrogen bond, whereas [{Ru(pap)(2)}(2)(mu-Ind(2-))](ClO4)(2) ([2](ClO4)(2)), isolated as the meso diastereoisomer with near-IR absorptions at 1162 and 991 nm, contains two metals 'bridged at 6.354 angstrom distance by the bischelating indigo dianion.. The spectroelectrochemical study of multiple reversible reduction and oxidation processes of 2(n)(n = 4+, 3+, 2+, 1+, 0, 17, 2, 3, 4) reveals the stepwise addition of electrons to the terminal pi-accepting pap ligands, whereas the oxidations occur predominantly at the. anionic indigo ligand, producing an EPA-identified indigo radical intermediate and revealing the suitability of deprotonated indigo as a sigma and pi-donating biSchelating bridge.

• 出版日期2016-3-21