Iodine monofluoride is an interhalogen compound of iodine and fluorine with formula IF. It is a chocolate-brown solid that decomposes at 0 °C,^[1] disproportionating to elemental iodine and iodine pentafluoride:

Iodine monofluoride

Names
IUPAC name Iodine monofluoride
Other names Iodine fluoride
Identifiers
CAS Number	13873-84-2 Y
3D model (JSmol)	Interactive image
ChemSpider	123150 Y
PubChem CID	139637
CompTox Dashboard (EPA)	DTXSID50160764
InChI InChI=1S/FI/c1-2 Y Key: PDJAZCSYYQODQF-UHFFFAOYSA-N Y InChI=1/FI/c1-2 Key: PDJAZCSYYQODQF-UHFFFAOYAT
SMILES FI
Properties
Chemical formula	IF
Molar mass	145.903 g/mol
Appearance	unstable brown solid
Melting point	−45 °C (−49 °F; 228 K)
Related compounds
Other anions	Iodine monochloride Iodine monobromide Astatine monoiodide
Other cations	Chlorine monofluoride Bromine monofluoride
Related compounds	Iodine trifluoride Iodine pentafluoride Iodine heptafluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

5 IF → 2 I₂ + IF₅

However, its molecular properties can still be precisely determined by spectroscopy: the iodine-fluorine distance is 190.9 pm and the I−F bond dissociation energy is around 277 kJ mol⁻¹. At 298 K, its standard enthalpy change of formation is Δ_fH° = −95.4 kJ mol⁻¹, and its Gibbs free energy is Δ_fG° = −117.6 kJ mol⁻¹.

It can be generated, albeit only fleetingly, by the reaction of the elements at −45 °C in CCl₃F:

I₂ + F₂ → 2 IF

It can also be generated by the reaction of iodine with iodine trifluoride at −78 °C in CCl₃F:

I₂ + IF₃ → 3 IF

The reaction of iodine with silver(I) fluoride at 0 °C also yields iodine monofluoride:

I₂ + AgF → IF + AgI