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Article

A Disilapentalene and a Stable Diradical from the Reaction of a Dilithiosilole with a Dichlorocyclopropene

Supporting Info

Irina S. Toulokhonova,^† Thomas C. Stringfellow,^† Sergei A. Ivanov,^† Artem Masunov,^‡ and Robert West*^†

Contribution from the Organosilicon Research Center, Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, and T-12 Theoretical Division, Los Alamos National Lab, Los Alamos, New Mexico 87544

J. Am. Chem. Soc., 2003, 125 (19), pp 5767–5773

DOI: 10.1021/ja020763h

Publication Date (Web): April 16, 2003

†

University of Wisconsin.

‡

Los Alamos National Lab.

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, west@chem.wisc.edu

Abstract

The reaction of 1,1-dilithio-2,3,4,5-tetraphenylsilole (1) with 1,1-dichloro-2,3-diphenylcyclopropene (2) leads to the novel 1,4-disila-1,4-dihydropentalene (4), as well as an exceptionally stable diradical for which the structure 3 is suggested. The diradical is unreactive toward water, methanol, and chloroform; upon heating it transforms into 4. Structure 3 for the paramagnetic species is proposed on the basis of EPR data and theoretical calculations. The trans−trans isomer of diradical 3 was calculated to be more stable than its cis−cis isomer. The strong and stable EPR signal in the reaction mixture is probably due to the trans−trans isomer of diradical 3 in the triplet state. A reaction scheme describing the formation of 3 and 4 is presented.