Thomas Brietzke, Wulfhard Mickler, Alexandra Kelling, Uwe Schilde, Hans-Jörg Krüger, Hans‐Jürgen Holdt

• AbstractRuthenium(II) complexes [Ru(L‐N4Me2)(dape)](PF6)2 {[1](PF6)2}, [Ru(L‐N4Me2)(tape)](PF6)2 {[2](PF6)2}, and [{Ru(L‐N4Me2)}2(μ‐tape)](PF6)4 {[3](PF6)4} were synthesized in two reaction steps by first reacting [Ru(DMSO)4Cl2] with tetraazamacrocyclic ligand N,N′‐dimethyl‐2,11‐diaza[3.3](2,6)‐pyridinophane (L‐N4Me2) in ethanol under microwave irradiation to the intermediate [Ru(L‐N4Me2)Cl2], which was subsequently, without further isolation, reacted with 1,12‐diazaperylene (dape) or 1,6,7,12‐tetraazaperylene (tape). X‐ray structures of [Ru(L‐N4Me2)(dape)](PF6)2, [Ru(L‐N4Me2)(tape)](PF6)2·acetone, and [{Ru(L‐N4Me2)}2(μ‐tape)](ClO4)4·MeCN were determined. The UV/Vis absorption spectra of [1](PF6)2, [2](PF6)2, and [3](PF6)4 in acetonitrile display intense low‐energy dπ(Ru)→π* (dape or tape) MLCT absorption bands centered at 579, 637, and 794 nm, respectively. Reversible metal oxidations for the bimetallic complex [{Ru(L‐N4Me2)}2(μ‐tape)]4+ ([3]4+) are detected at 1.69 and 1.28 V vs. SCE. The potential difference ΔE = 410 mV and the intervalence‐charge‐transfer (IVCT) transition at 2472 nm indicate a high degree of electronic interaction between the two ruthenium ions mediated through the tape bridging ligand. All three complexes, [1]2+, [2]2+, and [3]4+, were characterized by UV/Vis spectroelectrochemistry. The monooxidized and monoreduced states, [1]3+, [2]3+, [3]5+, and [1]+, [2]+, [3]3+, are accessible by reversible one‐electron oxidation and one‐electron reduction processes, respectively, as documented by the observation of several stable isosbestic points in the spectral progressions. The second reduction in each complex and the second oxidation in [3]4+ prove to be irreversible in these spectroelectrochemical experiments. Monoreduced species [1]+, [2]+, and [3]3+ yield EPR signals indicating that the unpaired electron is mainly centered on the “large surface” ligands dape or tape.