Unique bis-eta(5)/eta(1) bonding in a dianionic germole. Synthesis and structural characterization of the dilithium salt of the 2,3,4,5-tetraethyl germole dianion

Reaction of 1,1-dichloro-TEGeCp (TEGeCp = 2,3,4,5-tetraethyl-1-germacyclope ntadiene) with excess Li in tetrahydrofuran (THF) at room;temperature gave [TEGeCp2-]. 2[Li+] quantitatively. X-ray structure determination of this ge rmole dianion shows three Lithium cations around one germole ring in eta(1) , eta(5), and eta(5) sites to give the composition [eta(5)-Li . TMEDA][eta( 5)-Li](1/2)[eta(1)-Li](1/2)[Et4C4Ge] (TMEDA = N,N,N',N'-tetramethylethylene diamine). Nearly equal C-C bond distances in the Et4C4Ge ring indicate a de localized pi-system. Reactions of this germole dianion with trimethylchloro silane provided 1,1-bis(trimethylsilyl)-TEGeCp, in high yields.