2 (9). The allenylidene ligand of 4 undergoes the addition of carbodiimides to give iminiumazetidinylidenemethyl derivatives. The reaction with N,N′-dicyclohexylcarbodiimide affords [Os(η 5 -C 5 H 5 ){CHdCC(Ph) 2 N(Cy)+C+NdC(CH 2 ) 4 CH 2 }(CO)(P i Pr 3 )]PF 6 (10), whereas the reaction with N,N′-diisopropylcarbodiimide leads to [Os(η 5 -C 5 H 5 ){CHdCC(Ph) 2 N-( i Pr)+C+NdC(CH 3 ) 2 }(CO)(P i Pr 3 )]PF 6 (11). Complex 4 also reacts with methanol and aniline. The addition of methanol to the allenylidene 4 gives [Os(η 5 -C 5 H 5 ){C(OCH 3 )CHdCPh 2 }(CO)-(P i Pr 3 )]PF 6 (12), which undergoes deprotonation at the CHdCPh 2 group to afford Os(η 5 -C 5 H 5 ){C(OCH 3 )dCdCPh 2 }(CO)(P i Pr 3 ) (13). The addition of aniline leads to [Os(η 5 -C 5 H 5 )-{C(CHdCPh 2 )dNHPh}(CO)(P i Pr 3 )]PF 6 (14). Treatment of 14 with NaOCH 3 gives Os(η 5 -C 5 H 5 ){C(CHdCPh 2 )dNPh}(CO)(P i Pr 3 ) (15). Complexes 4, 7, and 8 have been characterized by X-ray diffraction analysis.