Cyclotetrasilenide Ion: A Reversible Redox System of Cyclotetrasilenyl Cation, Radical, and Anion

Abstract

Alkali-metal derivatives of cyclotetrasilenide (1−) were obtained by the treatment of cyclotetrasilenylium ion (1+) or cyclotetrasilenyl radical (1.) with Li, Na, and KC8 in diethyl ether. X-ray crystallographic analysis of 1− Li+ suggests that it has a cyclotetrasilene structure with a Si=Si bond in the ring, and that the lithium cation interacts with the three silicon atoms in the four-membered-ring skeleton. The ion 1− is readily oxidized to 1. and 1+; this is a reversible chemical redox system.