Stability Dependence on Redox–active Site Structure in Free Catechol‐ or Hydroquinone–substituted Polypyridylruthenium(II) Complexes

Abstract

Polypyridylruthenium(II) complexes with redox-active, structurally isomeric catechol or hydroquinone units were newly prepared to examine the structure-stability relationships in the redox-active sites. A marked difference based on the structure of the active site was confirmed with respect to the formation of the oxidized forms, i. e. the quinone complexes: only the para-isomer was completely converted into the corresponding quinone form. The conversion of Ru II to Ru III was not observed. Redox-mediated interconversion between the hydroquinone and para-quinone units is also reported.

Manganese(I) Diimine(tricarbonyl) Complexes with a Redox-active Free Catechol Unit: Redox-induced Molecular Conversion of Catechol to Quinone by Electrochemical Redox Reactions on the Complex

“…In addition, the bond parameters (Mn-C, Mn-N, Mn-Br, C-O lengths and Mn-C-O angles in Table 2) of 1 and the reference complex were similar to those reported for other fac-[MnBr(CO) 3 (N^N)]-type complexes (N^N = bidentate polypyridyl ligands). [28][29][30][31][32][33][34][35][36] For the catechol unit in 1, the C-OH bond lengths (1.379(7) and 1.357(8) ¡; ¡ = 10 ¹10 m) were similar to those of a previously reported similar complex ([MnBr(CO) 3 (dpc)]; 1.362(2) and 1.367(2) ¡), [37][38][39][40][41] suggesting that the catechol form was retained in 1. This phenomenon was supported by the data (1.355(4) and 1.367(5) ¡) obtained for the single-bonded methoxy groups (C-OCH 3 ) in the reference complex.…”