The terminal zirconium phosphinidene complex Cp(2)Zr(PR*)(PMe(3)) (R* = C6H2-2,4,6-t-Bu(3)) 2 has been synthesized in high yield, and its reactivity has been investigated. The compound Cp(2)ZrMe(PHR*) 1 is unstable with respect to the loss of methane; in the presence of PMe(3) this reaction yielded 2. Reactions of 2 with benzophenone, benzaldehyde, or isophthalaldehyde produced phosphaalkenes PhCH=PR* 3, Ph(2)C=PR* 4, and 1,3-C6H2(CH=PR*)(2) 5, respectively. PhN=C=PR* 6 resulted from the reaction of 2 with phenyl isothiocyanate while the use of cyclohexanone afforded the enolate Cp(2)Zr(PHR*)(OC6H9) 7. Phosphinidene group transfer also took place in reactions of 2 with the appropriate organic dihalide or epoxide. In this way phosphaalkenes CH2=PR* 8 and CHCl=PR* 9, phosphirane (CH(2)CH(2)PR*) 10, phospholane 1,2-C6H4(CH(2)PR*)(2) 11 and substituted phosphiranes (CH2CH)(CHCH2-PR*) 12, CH2C(CCH(2)PR*) 13, (PhCHCH(Ph)PR*) 15, and trans-(PhCHCH(2)PR*) 16 were synthesized. The use of propylene oxide yielded the enolate Cp(2)Zr(PHR*)(OCH2CH=CH2) 17. Similar reactions of 2 with heavier group 14 dihalides and sulfides furnished Cp(2)Zr(PR*(SiMe(2)Cl))Cl 18, PR*(SiMe(2)Cl)(2) 19, (Me(2)GeCl)(2) PR* 20, (Me(2)GePR*)(2) 21, (t-Bu(2)SnPR*)(2) 22, and (Me(2)SnPR*)(2) 23. Intramolecular phosphinidene transfer occurred in reactions of 2 with benzonitrile and dicyclohexylcarbodiimide, giving Cp(2)Zr(PMe(3))(NC(Ph)(PR*)) 25 and Cp(2)Zr(N(Cy))(2)C=PR* 26, respectively. Crystallographic data are reported for compounds 22, 25b, and 26.