The phosphorus analogue of piperidine (phosphacyclohexane, II) has been prepared and characterized by NMR. The proton on phosphorus appears as a broad triplet of triplets (Jaa= 12· 0 Hz; Jae= 2· 5). These couplings require the proton to be axial. No evidence for the presence of an equatorial isomer was obtained. The spectrum of phosphacyclohexane 1- sulfide (III) leads to similar conclusions. For phosphacyclohexane methiodide (IV), ...
