Abstract
It is well known that alkynyl groups have unique reactivities and are employed as pi-spacers. Although they are expected as an effective substituent for disilenes in terms of molecular transformation or construction of novel pi conjugated system, very few disilenes bearing alkynyl groups have been reported so far. We report here the first syntheses of 1,2-bis(trimethylsilylethynyl)disilenes as stable compounds and their structures and properties.
Reduction of dichlorosilanes 2 with lithium naphthalenide in THF at -78 C afforded the corresponding 1,2-bis(trimethylsilyl)ethynyldisilenes 1a and 1b as stable yellow crystals in 18 and 23%, respectively. In their UV-vis spectra, the absorption maxima of 1a and 1b appeared at 434 and 437 nm, respectively, which correspond to the pi-pi* transitions of the disilene moieties. MO calculations of 1 strongly indicated the conjugation between the Si=Si and CC moieties.
