Functionally Altered Ruthenaindenes with Electron-Rich and Electron-Poor Substituents

A series of ruthenaindene complexes containing electron-donating and -withdrawing groups were synthesized and characterized. The ruthenaindenes were synthesized from ruthenium butenynyl complexes which were formed by the treatment of Me2Ru­(PMe3)4 with 1,4-diaryl-1,3-butadiynes in methanol. Electrochemistry of the metal center in ruthenaindenes showed that the complexes with electron-donating groups on the aromatic ring have significantly lower oxidation potentials in comparison to complexes with electron-withdrawing groups. Even though the substitution of the aromatic ring with electron-donating/-withdrawing groups is remote from the metal center, the electronic properties of the substituents are relayed effectively to the metal center, indicating that the metal center in the ruthenaindenes is quite intimately embedded into the organic aromatic framework.