AN ELECTRON SPIN RESONANCE STUDY OF THE EFFECT OF THE CYCLOPENTADIENYL LIGAND ON THE PROPERTIES OF TIN(III) RADICALS AND THEIR ADDITION PRODUCTS

Article abstract of DOI:10.1016/S0022-328X(00)92578-6

A series of cyclopentadienyltin(III) radicals have been prepared by the reaction: Bu4-nCpnSn <*> Bu3-nCpnSn-radical+Cp-radical.The substitution reactions of these radicals with alkyl bromides, and their addition reactions with ethylene, biacetyl, 3,6-di-t-butyl-1,2-benzoquinone, and nitrocompounds, have been studied by ESR spectroscopy.The apparent reactivity decreases as the number of Cp ligands increases, and in this, and in the ESR parameters of the Sn^(IV) adducts which are formed, the Cp ligands resemble chloro groups rather than alkyl groups.This is supportedby the quadrupole splitting which is observed in the Moessbauer spectra of alkylcyclopentadienyl tin compounds.In η¹-Sn^(IV) compounds this effect may be ascribed to carbon-metal hyper-conjugation (?-?-interaction), but as yet there is no evidence whether CpSn^(III) radicals are ?(η¹) or ?(η^2-5) bonded.