Synthesis and spectroscopic studies of some novel bicyclic organotin compounds

Abstract

A number of new bicyclic organotin compounds have been synthesised by treating the corresponding organic halide with (trialkyl- or triarylstannyl)sodium in liquid ammonia. syn-7-Bromo-2-norbornene yielded mainly the anti-7-trimethyltin derivative when treated with (trimethylstannyl)sodium, but gave a tricyclic compound on reaction with (triphenylstannyl)sodium. anti-7-Bromobenzonorbornadiene gave a syn/anti mixture of the trimethylstannyl analogue together with that appeared to be a tricyclic derivative. 7-Chloro-2,5-norbornadiene readily gave the coreresponding 7-triphenylstannyl compound, but its trimethyltin analogue was formed only with difficulty and was unstable. The compounds were characterised by the PMR spectra, and the mechanism of formation is discussed. The addition of trimethyltin hydride to 2,5-norbornadiene resulted in a mixture of exo and endo-5-norbornenyl derivativevs. 13C NMR, Mössbauer and infrared spectroscopy were used in a search for donor-acceptor interactions between the tin atom and CC double bonds situated in stereochemically favourable positions, viz. 7-(trimethyl- and triphenylstannyl)-2,5-norbornadiene, and also endo-5-(trimethylstannyl)-2-norbenene. None of the spectroscopic techniques used revealed any evidence for this effect.