Structures of the Pentaphenylcyclopentadienyl Radical, (Pentaphenylcyclopentadienyl)tin(IV) Trichloride, and Bromo(chloro)bis(tetrahydrofuran)tin(II):  Products of the Reaction of C₅Ph₅X with SnX₂ (X = Cl, Br)

The reaction of SnCl 2 with C 5 Ph 5 Cl produces C 5 Ph 5 SnCl 3 ( 1 ) in an oxidative-addition reaction, while the pentaphenylcyclopentadienyl radical, C 5 Ph 5 •, ( 2 ) is obtained in the reactions of C 5 Ph 5 Br with SnCl 2 or SnBr 2 in diethyl ether/tetrahydrofuran (THF). In the reaction of SnCl 2 with C 5 Ph 5 Br, one of the tin halide products was shown to be SnBrCl(THF) 2 ( 3 ). The molecular structures of compounds 1 − 3 were determined by X-ray crystallography. Tin compound 1 is σ-bonded to the cyclopentadienyl ring; the radical 2 features a planar C 5 ring, and the structure of 3 consists of SnBrCl units coordinated by two THF molecules with an apparent stereochemical activity of the tin lone pair.