Cluster chemistry. Part 20. Preparation, X-ray crystal structures, and some reactions of [Fe3(CO)11(CNBut)] and [Fe3(CO)9(µ3-η2-CNBut)]

Abstract

The reaction between [Fe₃(CO)₁₂] and CNBu^t is initiated by Ph₂CO˙^– to give [Fe₃(CO)₁₁(CNBu^t)](1), characterised spectroscopically and by a full X-ray crystal structure analysis. Crystals of (1) are monoclinic, space group P2₁/n with a= 11.586(3), b= 11.819(3), c= 15.949(5)Å, β= 72.33(2)°, and Z= 4. The structure was solved by direct methods and refined to R= 0.025, R′= 0.027 for 1 641 reflections with l > 2.5σ(l). The structure is related to that of the C_2ν isomer of [Fe₃(CO)₁₂] with the CNBu^t ligand occupying an axial position of the unique iron atom. Thermal rearrangement of (1) gives [Fe₃(CO)₉(µ₃-η²-CNBu^t)](2) which contains a triply bridging six-electron-donor CNBu^t group. Reaction of (2) with H^– gives [Fe₃(CO)₉(HCNBu^t)]^– which can be protonated to form [Fe₃H(CO)₉(HCNBu^t)].