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

Article abstract of DOI:10.1021/ic50224a060

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-tetraphenyl-1,3-butadiene and diphenyltin(IV) dichloride, while the action of a glacial acetic acid-acetic anhydride mixture yields tetraphenylfuran and diphenyltin(IV) diacetate. The dihalostannoles form neutral adducts with pyridine, 2,2′-bipyridyl, and 1,10-phenanthroline and the double salt [XSnC₄(C₆H₅)₄·terpy] ⁺[X₂YSnC₄(C₆H₅) ₄]^- from 2,2′,2″-terpyridine where X = Y = Br, I = F, and Y = I. The structures of the substituted stannoles and the adducts of the dihalostannoles are discussed on the basis of tin-119m Mo?ssbauer and infrared spectroscopic evidence.