H NMR of the α,α′-bipyridine and o-phenanthroline adducts of n-butyltin trichloride

¹H NMR spectra of the α,α′-bipyridine adduct of n-BuSnCl₃ indicated the non-equivalence of the two pyridine rings. In particular the signals of the proton on the carbon atom adjacent to the two nitrogen atoms were widely separated. Similar spectral behavior was observed in the o-phenanthroline adduct. These adducts therefore are concluded to have the n-butyl group lying on the N---Sn---N plane of the hexacoordinated complexes. The configurational rearrangement of these adducts was markedly accelerated in the presence of excess n-BuSnCl₃.