Insertion of aliphatic 1-alkynes such as tert-butylacetylene, 1-hexyne or 1,6-heptadiyne into the Pt–H bond of the heterobimetallic hydride complex [(OC) 3 Fe{Si(OMe) 3 }(μ-dppm)Pt(H)(PPh 3 )] (1) (dppm=Ph 2 PCH 2 PPh 2 ) leads to the formation of an isomeric mixture of μ-vinylidene complexes [(OC) 3 Fe{μ-CC(H)R}(μ-dppm)Pt(PPh 3 )] (2a: R=tert-Bu, 2b: R=n-Bu, 2c: R=(CH 2 ) 3 –CCH) and dimetallacyclopentenones [(OC) 2 Fe{μ-C(=O)CRCH}(μ-dppm)Pt(PPh 3 )] (3a: R=tert-Bu, 3b: R=n-Bu, 3c: R=(CH 2 ) 3 –CCH). The molecular structures of 2a and 3c have been determined by single-crystal X-ray diffraction.