Reactions of tetracarbonyihydridoferrate(0) with acetylenes in aprotic solvents: (1—3-η-acryloyl)tricarbonylferrates and tricarbonyl(1—3-η-prop-2-en-1-ylidene)iron complexes

Abstract

The ion [FeH(CO)₄]^– reacts with acetylenes, HCCCOR (R = OMe, Me, or H) or MeO₂CCCCO₂Me, to give [ Fe(η³- H R¹CCR²CO)(CO)₃]³(3) by trans addition of the hydride to the acetylenic bond. Protonation of (3) gives [Fe(η-HR¹CCR²H)(CO)₄](5) by an intramolecular decarbonylation reaction. Methylation of (3a; R¹= H, R²= CO₂Me) and (3b; R^I= R²= CO₂Me) with SFO₂(OMe) or [OMe₃][BF₄] gives [Fe{η³-C(OMe)C(CO₂Me){CH₂}(CO)₃](6a) and [Fe{η³-trans-C(OMe)C(CO₂Me)C(CO₂Me)H}(CO)₃](6b). Oxidation of (6a) and (6b) with pyridine /N-oxide gives [Fe{η-H₂CC(CO₂Me)₂}(CO)₃(py)](7a) and [Fe{η-H(MeCO₂)CC(CO₂Me)₂}-(CO)₃(py)](7b), respectively.