In the last decade, much attention has been focused on the anions and dianions of siloles [1] and germoles, [1f, 2] which are heavier congeners of the cyclopentadienyl anion.[3] The degree of aromaticity of silolyl anions depends on the substituent, [1b,f] while the germolyl anions do not show aromaticity because the negative charge is localized on the germanium atom. [1f, 2a,2c] In contrast, the negative charges in the dianions of siloles and germoles are significantly delocalized in the C 4 M (M = Si, Ge) ring and they were concluded to be aromatic. [1d-f, 2b,2d,2e, 4] The aromatic delocalization in these dianions was evidenced by NMR studies, calculations, and Xray crystal structural analyses, which showed no alternation of the CÀC bonds within the ring. In contrast to the wellinvestigated mono-and dianions of siloles and germoles, neither mono-nor dianions of stannoles had been reported before we undertook a study of such species a few years ago.

The first syntheses of mono- and dianions of stannole were accomplished by transmetallation or reduction of the novel bi(1,1-stannole).

The synthesis of stannole anions bearing various substituents on the tin atom is described. The reduction of hexaphenylstannole by the proper amount of lithium gave 1,2,3,4,5‐pentaphenylstannole anion 1. The reaction of 1 with 1,n‐dihaloalkanes (n = 1, 3, 4, 5, 6) gave the corresponding 1,n‐bis(1‐stannacyclopentadien‐1‐yl)alkanes. In contrast, the reaction of 1 with 1,2‐dihaloalkanes gave the 1,1′‐bistannole. The reactions of stannole dianion 3 with an equimolar amount of bulky alkyl, aryl, silyl, and stannyl halides gave the corresponding stannole anions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

In the last decade, much attention has been focused on the anions and dianions of siloles [1] and germoles, [1f, 2] which are heavier congeners of the cyclopentadienyl anion.[3] The degree of aromaticity of silolyl anions depends on the substituent, [1b,f] while the germolyl anions do not show aromaticity because the negative charge is localized on the germanium atom. [1f, 2a,2c] In contrast, the negative charges in the dianions of siloles and germoles are significantly delocalized in the C 4 M (M = Si, Ge) ring and they were concluded to be aromatic. [1d-f, 2b,2d,2e, 4] The aromatic delocalization in these dianions was evidenced by NMR studies, calculations, and Xray crystal structural analyses, which showed no alternation of the CÀC bonds within the ring. In contrast to the wellinvestigated mono-and dianions of siloles and germoles, neither mono-nor dianions of stannoles had been reported before we undertook a study of such species a few years ago.

Reaction of tert-butylchloride with the stannole dianion first and simply prepared by the reduction of 1,1,2,3,4,5-hexaphenylstannole with lithium in ether gave 1-tert-butylstannole anion which was characterized by 1H, 13C, 119Sn, and 7Li NMR spectra and whose reactivities were investigated.