Reactivity of silyl-substituted heterobimetallic iron–platinum hydride complexes: Part III. Alkyne insertions into the platinum–hydride bond and competition between μ-vinylidene and dimetallacyclopentenone formation

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)3Fe{Si(OMe)3}(μ-dppm)Pt(H)(PPh3)] (1) (dppm = Ph2PCH2PPh2) leads to the formation of an isomeric mixture of μ-vinylidene complexes [(OC)3Fe{μ-Cdouble bond; length as m-dashC(H)R}(μ-dppm)Pt(PPh3)] (2a: R = tert-Bu, 2b: R = n-Bu, 2c: R = (CH2)3–Ctriple bond; length of mdashCH) and dimetallacyclopentenones [(OC)2Fe{μ-C(=O)CRdouble bond; length as m-dashCH}(μ-dppm)Pt(PPh3)] (3a: R = tert-Bu, 3b: R = n-Bu, 3c: R = (CH2)3–Ctriple bond; length of mdashCH). The molecular structures of 2a and 3c have been determined by single-crystal X-ray diffraction.