Chlorobis(dppe)iron hydride

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.^[1]

Chlorobis(dppe)iron hydride

Names
IUPAC name Chlorohydridobis(bis-1,2-(diphenylphosphino)ethane)iron(II)
Identifiers
CAS Number	32490-70-3
3D model (JSmol)	Interactive image
PubChem CID	165365653
CompTox Dashboard (EPA)	DTXSID001045863
InChI InChI=1S/2C26H24P2.ClH.Fe.H/c2*1-5-13-23(14-6-1)27(24-15-7-2-8-16-24)21-22-28(25-17-9-3-10-18-25)26-19-11-4-12-20-26;;;/h2*1-20H,21-22H2;1H;;/q;;;+1;/p-1 Key: NSXBDVRBULAONI-UHFFFAOYSA-M
SMILES Cl[FeH-4]56([P+](c1ccccc1)(c2ccccc2)CC[P+]5(c3ccccc3)c4ccccc4)[P+](c1ccccc1)(c2ccccc2)CC[P+]6(c3ccccc3)c4ccccc4
Properties
Chemical formula	C52H49ClFeP4
Molar mass	889.09
Appearance	red-violet solid
Melting point	195 °C (383 °F; 468 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Structure

The complex exhibits octahedral molecular geometry. The chloride and hydride ligands are mutually trans.^[2] 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:^[3]

FeCl₂ + 2 dppe + Na[BH₄] → NaCl + ½ B₂H₆ + HFeCl(dppe)₂

"Top-view" of the structure of 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:^[4]

HFeCl(dppe)₂ + NaBF₄ + N₂ → [HFe(N₂)(dppe)₂]BF₄ + NaCl

HFeCl(dppe)₂ + NaBF₄ + H₂ → [HFe(H₂)(dppe)₂]BF₄ + NaCl

References

1. Morris RH (2008). "Dihydrogen, Dihydride and in Between: Nmr and Structural Properties of Iron Group Complexes". Coord. Chem. Rev. 2252 (21–22): 2381–2394. doi:10.1016/j.ccr.2008.01.010.
2. Lee, J.; Jung, G.; Lee, S. W. Structure of trans-chlorohydridobis(diphenylphosphinoethane)iron(II). Bull. Korean. Chem. 1998, 19, 267. ISSN 0253-2964
3. Giannoccaro, P.; Sacco, A. (1977). "Bis[Ethylenebis(Diphenylphosphine)]-Hydridoiron Complexes". Inorganic Syntheses. Vol. 17. pp. 69–71. doi:10.1002/9780470132487.ch19. ISBN 9780470132487. {{cite book}}: |journal= ignored (help)
4. Bautista MT, Bynum LD, Schauer CK (1996). "Synthesis of η²-Dihydrogen Complex, trans-{Fe(η²-H₂)(H)[1,2-bis(diphenylphosphino)ethane]₂}[BF₄]: An Experiment for an Advanced Inorganic Chemistry Laboratory Involving Synthesis and NMR Properties of an η²-H₂ Complex". Journal of Chemical Education. 73 (10): 988–991. doi:10.1021/ed073p988.