The reaction of 1,2-bis(N,N-dimethylaminochloro-phosphanyl)-1,2-dicarba-closo-dodecaborane(12) and lithiated phenylacetylene gives a five-membered dihydrophosphole derivative with an exocyclic phosphanyl group. This unexpected reaction opens new possibilities for the synthesis of carbaborane-containing phosphorus heterocycles. P,P'-alkynylated 1,2-bis(phosphanyl)-1,2-dicarba-closo-dodecaborane(12)s are obtained from alkynylchlorophosphanes and dilithiated carbaborane. This new class of alkynes can be used for future applications in cyclizations and polymerizations.