Compounds with carbon phosphorus(III) multiple bonds are called phosphaalkenes (RC=PR) and phosphaalkynes (RC≡P). They are similar in structure, but not in reactivity, to imines (RC=NR) and nitriles (RC≡N), respectively. In the compound phosphorine, one carbon atom in benzene is replaced by phosphorus. Species of this type are relatively rare but for that reason are of interest to researchers.  A general method for the synthesis of phosphaalkenes is by 1,2-elimination of suitable precursors, initiated thermally or by base such as DBU, DABCO, or triethylamine:
Thermolysis of MePH generates CH=PMe, an unstable species in the condensed phase.