Synthesis and properties of stable 1,2-bis(metallocenyl)disilenes: Novel d-π conjugated systems with a Si=Si double bond

Stable 1,2-bis(metallocenyl)disilenes were synthesized for the first time and were characterized by spectroscopic and X-ray crystallographic analyses. On the basis of cyclic voltammograms, (E)-1,2-bis(ferrocenyl)-1,2-bis(2,4,6- triisopropylphenyl)disilene (1a) was found to be a stable five-electron redox system with four steps, while (E)-1,2-bis(ruthenocenyl)-1,2-bis(2,4,6- triisopropylphenyl)disilene (1b) showed four-step redox couples with four electrons. The UV-vis spectra and theoretical calculations for these disilenes suggested that they should be novel d-π conjugated systems containing a disilene unit. In addition, chalcogenation reactions of 1a resulted in the formation of new heterocyclic compounds bearing ferrocenyl units. For example, the first stable 1,2,3,4-dithiadisiletane derivative was obtained by the sulfurization reaction of 1a.