Rearrangement of a P Butterfly Complex-The Formation of a Homoleptic Phosphorus-Iron Sandwich Complex.

The versatile coordination behavior of the P butterfly complex [{Cp'''Fe(CO) } (μ,η -P )] (1, Cp'''=η -C H Bu ) towards different iron(II) compounds is presented. The reaction of 1 with [FeBr ⋅dme] (dme=dimethoxyethane) leads to the chelate complex [{Cp'''Fe(CO) } (μ ,η -P ){FeBr }] (2), whereas, in the reaction with [Fe(CH CN) ][PF ] , an unprecedented rearrangement of the P butterfly structural motif leads to the cyclo-P moiety in {(Cp'''Fe(CO) ) (μ ,η -P )} Fe][PF ] (3). Complex 3 represents the first fully characterized "carbon-free" sandwich complex containing cyclo-P R ligands in a homoleptic-like iron-phosphorus-containing molecule. Alternatively, 2 can be transformed into 3 by halogen abstraction and subsequent coordination of 1. The additional isolated side products, [{Cp'''Fe(CO) } (μ ,η -P ){Cp'''Fe(CO)}][PF ] (4) and [{Cp'''Fe(CO) } (μ ,η -P ){Cp'''Fe}][PF ] (5), give insight into the stepwise activation of the P butterfly moiety in 1.