An 1H and 13C NMR study of pentane-2,4-dione tellurium(II) compounds; chemical shifts, 125Te1H and 125Te13C couplings

1H and 13C NMR data are reported for pentane-2,4-dione tellurium(II) compounds which contain a 6-membered tellurane ring bearing methyl or ethyl substituents. The 125TeCH coupling constants are particularly interesting in that they are highly stereospecific, viz. ∼60 Hz and 0–8 Hz for equatorial and axial protons, respectively, in the chair conformation. 1J(TeC) and 2J(TeCC) couplings lie in the ranges 118–146 Hz and 44–49 Hz, respectively. Geminal HCH couplings in these compounds (9–11 Hz) are lower than analogous values in tellurane or in cyclohexane-1,3-diones.