Reactions of group IVB metal dihalides with η1-allyl complexes of η5-cyclopentadienyldicarbonyliron

The reactions of tin(II) chloride in tetrahydrofuran with the η¹-allyl systems, [η⁵-Cp(CO)₂Fe allyll, have been reexamined, and an extension made to SnBr₂ and GeCl₂.dioxan. The insertion compounds, [η⁵-Cp(CO)₂FeMX₂ allyl], which contain the Group IVB element bound to iron, are the major products, but, in the presence of excess metal dihalide, these slowly react to form the trihalometal compounds [η⁵-Cp(CO)₂FeMX₃]. The insertion reactions are inhibited by small amounts of a radical scavenger, and occur initially with allylic rearrangement. In methanol, the process is more complex; an unknown species, possibly an iron-olefin dipolar intermediate, and substantial amounts of trihalometal-iron compounds are formed additionally. A mechanistic scheme for the processes is discussed.