Cyclopentadienyliron dicarbonyl iodide

Cyclopentadienyliron dicarbonyl iodide is an organoiron compound with the formula (C₅H₅)Fe(CO)₂I. It is a dark brown solid that is soluble in common organic solvents. (C₅H₅)Fe(CO)₂I, or FpI as it is often known, is an intermediate for the preparation of other organoiron compounds such as in ferraboranes.

Cyclopentadienyliron dicarbonyl iodide

Identifiers
CAS Number	12078-28-3 Y
3D model (JSmol)	Interactive image
ChemSpider	35466814
ECHA InfoCard	100.155.006
EC Number	626-622-8
PubChem CID	138114916
InChI InChI=1S/C5H5.2CO.Fe.HI/c1-2-4-5-3-1;2*1-2;;/h1-5H;;;;1H/p-1 Key: XPSYTVVYYIGNSG-UHFFFAOYSA-M
SMILES [C-]#[O+].[C-]#[O+].C1=C[CH]C=C1.[Fe].[I-]
Properties
Chemical formula	C7H5FeIO2
Molar mass	303.864 g·mol−1
Appearance	Black crystalline solid (density = 2.374 g/cm3)
Melting point	119 °C (246 °F; 392 K)
Structure
Space group	Cs
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H312, H332
Safety data sheet (SDS)	Here
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Preparation

Cyclopentadienyliron dicarbonyl iodide is synthesized by the reaction of cyclopentadienyliron dicarbonyl dimer with I₂:^[1]

Cp₂Fe₂(CO)₄ + I₂ → 2 CpFe(CO)₂I

It was first reported by Pauson and Hallam.^[2]

Structure

The compound has C_s symmetry, with a mirror plane intersecting one carbon of the Cp ring as well as the iron and iodide centre. The compound adopts a piano stool structure: the cyclopentadienyl ligand is the "seat" and three other ligands are "legs". Such compounds are members of the half-sandwich family of compounds, which is a subgroup of the metallocenes. X-ray crystallography shows the following features: Fe-Cp centroid = 1.72, Fe-I = 2.61, and Fe-CO = 1.78 Å.^[3]

Electron counting of this iron(II) complex indicates that (C₅H₅)Fe(CO)₂I is an 18-electron complex: using the neutral method there are 8 electrons from the iron, 5 electrons from the cyclopentadienyl anion, 2 electrons from each of the carbonyls, and 1 electron from the iodide.

References

1. King, R. B.; Stone, F. G. A "Cyclopentadienyl Metal Carbonyls and some Derivatives" Inorg. Synth. 1963, volume 7, pp. 99-115. doi:10.1002/9780470132388.ch31
2. B. F. Hallam, P. L. Pauson "Ferrocene Derivatives. Part III. Cyclopentadienyliron Carbonyls" J. Chem. Soc. 1956, pp. 3031-3037.
3. Zeller, M.; Lazich, E.; Hunter, A. D. (2003). "Dicarbonyl(η⁵-cyclopentadienyl)iodoiron(II)". Acta Crystallographica Section E. 59 (10): m914–m915. doi:10.1107/S1600536803019950.