Chlorobis(dppe)iron hydride is a coordination complex with the formula HFeCl(dppe)2, where dppe is the bidentate ligand 1,2-bis(diphenylphosphino)ethane. It is a red-violet solid. The compound has attracted much attention as a precursor to dihydrogen complexes.
Structure The complex exhibits octahedral molecular geometry. The chloride and hydride ligands are mutually trans.Lee, J.; Jung, G.; Lee, S. W. Structure of trans-chlorohydridobis(diphenylphosphinoethane)iron(II). Bull. Korean. Chem. 1998, 19, 267. The bond distances between the iron metal atom and the coordinating ligands are given by the following: Bond Bond distance Fe-P1 2.238 Fe-P2 2.256 Fe-P3 2.236 Fe-P4 2.255 Fe-Cl 2.404 Fe-H 1.313 Synthesis and reactions The compound is synthesized according to the following idealized reaction: FeCl2 + 2 dppe + Na[BH4] → NaCl + ½ B2H6 + HFeCl(dppe)2
In the course of this conversion, high-spin complex FeCl2(dppe)2 converts to low-spin HFeCl(dppe)2.
The complex HFeCl[(dppe)2 exhibits a number of reactions associated with the remaining Fe-Cl bond. Reaction of the complex with sodium borohydride gives the dihydride complex: HFeCl(dppe)2 + NaBH4 → H2Fe(dppe)2 + NaCl + "BH3"
Removal of chloride using sodium tetrafluorborate under and atmostphere of hydrogen or nitrogen gives the dinitrogen and dihydrogen complexes: HFeCl(dppe)2 + NaBF4 + N2 → [HFe(N2)(dppe)2]BF4 + NaCl HFeCl(dppe)2 + NaBF4 + H2 → [HFe(H2)(dppe)2]BF4 + NaCl
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