A zirconacyclopentene incorporating a carboranyl unit 1,2-[Cp2ZrC(Et)=C(Et)]-1,2-C2B10H10 (1), an analogue of well-known zirconacyclopentadienes, was prepared and fully characterized from the reaction of Cp2Zr(mu-Cl)(mu-C2B10H10)Li(OEt2)(2) with EtC OCEt in reflux toluene. Complex I resembles zirconacyclopentadienes in some reactions, and on the other hand, it has unique properties of its own. Many carborane derivatives with interesting structural features such as 1-[Cl(Et)=C(Et)]-1,2-C2B10H11, naphthalocarborane, and 1,2-[C(Et)=C(Et)]-1,2-C2B10H10 can be conveniently prepared from 1. This work shows that 1 provides a very valuable entry point to the synthesis of various kinds of carborane derivatives that can not be prepared by conventional methods.