Synthesis and Characterization of Dibenzoheterocycle‐Bridged Dinuclear Ruthenium Alkynyl and Vinyl Complexes

Abstract

A series of dinuclear ruthenium alkynyl and vinyl complexes bridged by carbazole, dibenzofuran, dibenzothiophene, and fluorenone have been prepared, and some representative molecular structures have been determined. The electrochemical and spectroscopic properties of the compounds were explored by cyclic voltammetry (CV), square-wave voltammetry (SWV), and in situ infrared and UV/Vis/near-IR spectroelectrochemical methods. The electrochemical results

Redox‐Active Tetraruthenium Macrocycles Built from 1,4‐Divinylphenylene‐Bridged Diruthenium Complexes

“…Relative metal/bridging ligand contributions to the redox orbitals critically depend on the torsions around the Ru−alkenyl and the alkenyl−arylene bonds. The formation of the radical cations 1‐OBu + and 2‐H + is also accompanied by the development of a highly intense electronic transition at about 7500 cm −1 (1330 nm) resulting from a π→π* SOMO−1→SOMO (β‐HOSO→β‐LUSO) transition within the open‐shell diruthenium divinylphenylene chromophore –,,,,. This band bleaches on further oxidation to the corresponding dications…”

“…Hence, their neutral forms are virtually transparent at wavelengths above 580 nm (X=terminal anionic ligand) or 400 nm (X=bidentate monoanionic ligand), while their radical cations exhibit intense absorptions in the visible (Vis) and deep in the near infrared (NIR). The corresponding dications finally absorb strongly at the borderline between the Vis and the NIR ,,,,. It was our hope that coordination cages or metallamacrocycles comprising such entities and more complex architectures resulting from their ordered assembly would maintain or even amplify the favorable properties of these building blocks with the added prospect of paramagnetic behavior in states where the individual divinylphenylene‐bridged diruthenium sides exist in open‐shell electron configurations.…”

Electronically Strongly Coupled Divinylheterocyclic‐Bridged Diruthenium Complexes

“…As observed for complexes with large bridge contributions to the "redox-orbitals" the separation between the individual redoxe vents DE8' increases with increasing electronrichness of the bridge, which in turn better stabilizes the oneelectron-oxidized product. [26,27] For example, the group of Liu [72] found the same trend of increasing DE8',w hen they investigated as eries of dibenzoheterocycle-bridged divinyl ruthenium complexes (dichloromethane, [nBu 4 N][PF 6 ]a ss upporting electrolyte; [ 3,7-…”

Conformational Tuning of the Intramolecular Electronic Coupling in Molecular‐Wire Biruthenium Complexes Bridged by Biphenyl Derivatives

“…In contrast, the solvent polarityh as no influence on the MLCT transitions (6304 cm À1 for 4a + + and 6109 cm À1 for 4b + + ). [67,68] The observed width at half-height ), which implies partially delocalized behavioro ft he MV system. [43] By comparison of the IVCT transitions, it was found that the IVCT band for 4a + + is slightly more intense (e = 802) than that of 4b + + (e= 500).…”