SYNTHESIS AND CHARACTERIZATION OF DILITHIUM 1,2-DISILAACENAPHTHENEDIIDE

Reaction of 1,2-dichloro-1,2-diisopropyl-1,2-disilaacenaphthene (1) with excess lithium resulted in formation of the corresponding dilithium 1,2-disilaacenaphthenediide (2) as the 1,2-dilithiodisilane. On treatment with methyl iodide and methanol, 2 was converted into the corresponding 1,2-dimethyl- and 1,2-dihydro-1,2-disilaacenaphthene derivatives, respectively. NMR spectroscopic analysis and theoretical investigation strongly support the dilithiodisilane structure (2a) in which the negative charge is localized on the silicon. atom and one lithium atom interacts with one silicon atom, respectively. The measurement of the Si-Li coupling at low temperature shows that a Si-Li bond has a partial covalency.