Synthesis of Tetraphenylstannacyclopentadienes (Stannoles). I. Alkylation of 1,1-Dihalostannoles Leading to Lithium 1,1-Di-h1-cyclopentadienyl-1-halo-2,3,4,5-tetraphenylstannole, an (R4SnX)-Anion with Pseudorotating Axial- and Equatorial-Fluxional h1-Cyclopentadienyl Groups.
OKLAHOMA UNIV NORMAN DEPT OF CHEMISTRY
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1,1-Dibromo- and 1,1-diiodo-2,3,4,5-tetraphenylstannacyclopentadiene dibromo- and diiodostannole formed from controlled phenyltin cleavage of hexaphenylstannole by elemental bromine and iodine, respectively, undergo conventional alkylation by methyllithium to form the expected 1,1-dimethylstannole, but treatment with excess lithium or thallium cyclopentadiene yields cubic crystals whose analytical data agree with the formulation XC5H52SnC4C4H54M where XBr, MLi, Tl and where XI, MLi. Infrared nu asym and nu sym Sn-Br absorptions in the starting dibromostannole are replaced by a single feature at 225cm in the XBr products, and absorptions in the 3000 and 1595-695 cm-1 region specify the h1-cyclopentadiene nature of the C5H5Sn unit. Only slight broadening of the fluxional C5H5 resonances is observed on cooling to -100 C however, the two resonances of equal intensity undergo reversible collapse to a single, unshifted peak at 90 deg for XBr and 100 C for XI.
- Organic Chemistry