Synthesis, structure and redox chemistry of 1,2-bis(ruthenocenyl)-ethylene derivatives: a novel structural rearrangement to a (mu-eta(6):eta(6)-pentafulvadiene)diruthenium complex upon two-electron oxidation

摘要

Formylruthenocene, 1-formyl-1',2',3',4',5'-pentamethylruthenocene and 1-formyl-2,3,4,5-tetramethylruthenocene were treated with TiCl4-Zn in thf to afford the corresponding ethylene derivatives trans-1,2-bis(ruthenocenyl)ethylene, trans-1,2-bis(1',2',3',4',5'-pentamethylruthenocenyl)ethylene and trans-1,2-bis(2,3,4,5-tetramethylruthenocenyl)ethylene in excellent yields. Similarly, the dimethyl analogs were obtained from acetylruthenocene and 1-acetyl-1',2',3',4',5'-pentamethylruthenocene in good yields. Cyclic voltammograms of the ethylene complexes showed an irreversible two-electron oxidation wave at significantly lower potential than that of pentamethylruthenocene or ruthenocene. Two-electron chemical oxidation of these complexes with p-benzoquinone-BF3. OEt2 gave stable dicationic (mu-eta(6): eta(6)-pentafulvadiene)diruthenium complexes in moderate yields. The molecular structures of five complexes were determined by X-ray diffraction. [References: 67]