Synthesis of tetraphenylstannacyclopentadienes (stannoles). 2. Derivatives and adducts of 1,1-dihalo-2,3,4,5-tetraphenylstannoles

1,1-Dibromo- and 1,1-diiodo-2,3,4,5-tetraphenyl-1-stannacyclopentadiene, dihalotetraphenylstannoles, XYSnC4(C6H5)4, can be derivatized to form a series of disubstituted products in which X = Y = N3, iso-NCO, iso-SCN, OC(O)CH3, SC(S)N(C2H5)2, N(CH3)2 and P(C6H5)2. Fluorination by KF in acetone results in the X = F, Y = Br or Y = I product only, and lithioamination by LiN(Si(CH3)3)2 yields the X = N(Si(CH3)3)2, Y = Br product only. Attempted synthesis of the dihalostannoles by halogenation of the intermediate tin(II) stannole from 1,4-dilithio-1,2,3,4-tetraphenyl-1,3-butadiene and tin(II) chloride yields only the ring-opened products (4-bromo-1,2,3,4-tetraphenylbutadienyl)tin tribromide or (4-iodo-1,2,3,4-tetraphenylbutadienyl)tin triiodide. Even gentle chlorination of hexaphenylstannole by elemental chlorine cleaves the ring tin-carbon bonds to form cis-cis-1,4-dichloro-1,2,3,4-tetraphenylbutadiene-1,3 and diphenyltin dichloride, while the action of a glacial acetic acid/acetic anhydride mixture yields tetraphenylfuran and diphenyltin diacetate.