Hafnium(III) iodide

Names
IUPAC name

Hafnium triiodide

Identifiers

CAS Number

* 13779-73-2 Y

3D model (JSmol)

* Interactive image

PubChem CID

* 161242838 charge error

InChI

* InChI=1S/Hf.3HI/h;3*1H/q+3;;;/p-3

Key: VAFXHNPAMHBKMS-UHFFFAOYSA-K

SMILES

* [I-].[I-].[I-].[Hf+3]

Properties

Chemical formula

| HfI3
Molar mass | 559.20 g·mol−1
Appearance  | black crystals[1]
Melting point | decomposes
Related compounds

Other anions

| Hafnium(III) chloride
Hafnium(III) bromide

Other cations

| Titanium(III) iodide
Zirconium(III) iodide

Related compounds

| Hafnium(IV) iodide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Infobox references

Chemical compound

Hafnium(III) iodide is an inorganic compound of hafnium and iodine with the formula Hf I3. It is a black solid.[2]

## Preparation[edit]

Like other group 4 trihalides, hafnium(III) iodide can be prepared from hafnium(IV) iodide by high-temperature reduction with hafnium metal, although incomplete reaction and contamination of the product with excess metal often occurs.[2]

3 Hf I4 \+ Hf → 4 Hf I3

Other metals can be used as the reducing agent, for example aluminium. The product is often nonstoichiometric, with the compositions Hf I3.2–3.3 and Hf I3.0–3.5 reported.[3][4]

## Structure and bonding[edit]

Hafnium(III) iodide adopts the same crystal structure as zirconium(III) iodide.[5] This is very similar to the β-TiCl3 structure.[2] The structure is based on hexagonal close packing of iodide ions with one third of the octahedral interstices occupied by Hf3+ ions.[2] It consists of parallel chains of face-sharing {HfI6} octahedra.[5]

Hafnium(III) iodide has a lower magnetic moment than is expected for the d1 metal ion Hf3+, indicating non-negligible Hf–Hf bonding.[2] The Hf–Hf separation was originally reported to be 3.295 Å,[6] but a subsequent study of nonstoichiometric hafnium(III) iodide indicated a lower symmetry structure.[3]

## Reactivity[edit]

Like the chloride and bromide, hafnium(III) iodide is a powerful enough reducing agent to reduce water and therefore does not have any aqueous chemistry.[2]

## References[edit]

1. ^ William M. Haynes, ed. (2013). CRC Handbook of Chemistry and Physics (93rd ed.). CRC Press. p. 4–66. ISBN 978-1466571143.
2. ^ a b c d e f Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 965\. ISBN 978-0-08-037941-8.
3. ^ a b Struss, Arthur W.; Corbett, John D. (1969). "Lower halides of hafnium. Nonstoichiometric hafnium triiodide phase". Inorg. Chem. 8 (2): 227–232. doi:10.1021/ic50072a009.
4. ^ Clark, R. J. H.; Bradley, D. C.; Thornton, P. (2013). The Chemistry of Titanium, Zirconium and Hafnium Pergamon Texts in Inorganic Chemistry. Elsevier. p. 432\. ISBN 978-1-4831-5921-8.
5. ^ a b Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. pp. 418–419. ISBN 978-0-19-965763-6.
6. ^ Dahl, Lawrence F.; Chiang, Tao-I; Seabaugh, Pyrtle W.; Larsen, Edwin M. (1964). "Structural Studies of Zirconium Trihalides and Hafnium Triiodide". Inorg. Chem. 3 (9): 1236–1242. doi:10.1021/ic50019a008.

* v
* t
* e

Hafnium compounds

Hf(II)|

* HfB2

Hf(III)|

* HfI3

Hf(IV)|

* HfC
* HfBr4
* HfCl4
* HfF4
* HfI4
* Hf(C5H7O2)4
* Hf(OSO2CF3)4
* HfO2
* Hf(NO3)4
* HfSiO4
* HfS2
* La2Hf2O7
* Ta4HfC5
* CHf2N

* v
* t
* e

Salts and covalent derivatives of the iodide ion

| HI
+H |  |  |  | He

|
|
|
|

LiI | BeI2 | BI3
+BO3 | CI4
+C | NI3
NH4I
+N | I2O4
I2O5
I4O9 | IF
IF3
IF5
IF7 | Ne
NaI | MgI2 | AlI
AlI3 | SiI4 | PI3
P2I4

PI5 | S2I2 | ICl
ICl3 | Ar
KI | CaI2 |  | ScI3 | TiI2
TiI3
TiI4 | VI2
VI3 | CrI2
CrI3 | MnI2 | FeI2
FeI3 | CoI2 | NiI2
-Ni | CuI | ZnI2 | GaI
GaI3 | GeI2
GeI4
+Ge | AsI3
As2I4
+As | Se  | IBr
IBr3 | Kr
RbI
RbI3 | SrI2 |  | YI3 | ZrI3
ZrI4 | NbI4
NbI5 | MoI2
MoI3 | TcI3 | RuI3 | RhI3 | PdI2 | AgI | CdI2 | InI
InI3 | SnI2
SnI4 | SbI3
+Sb | TeI4
+Te | I− | Xe
CsI
CsI3 | BaI2 |  | LuI3 | HfI3
HfI4 | TaI4
TaI5 | WI2
WI3 | ReI3
ReI
4 | OsI
OsI2
OsI3 | IrI3
IrI
4 | PtI2 | AuI
AuI3 | Hg2I2
HgI2 | TlI
TlI3 | PbI2 | BiI3 | PoI2
PoI4 | AtI | Rn
Fr  | RaI2 |  | Lr  | Rf  | Db  | Sg  | Bh  | Hs  | Mt  | Ds  | Rg  | Cn  | Nh  | Fl  | Mc  | Lv  | Ts  | Og
| ↓  |  |
| LaI2
LaI3 | CeI2
CeI3 | PrI2
PrI3 | NdI2
NdI3 | PmI3 | SmI2
SmI3 | EuI2
EuI3 | GdI2
GdI3 | TbI3 | DyI2
DyI
3 | HoI3 | ErI3 | TmI3 | YbI2
YbI3
AcI3 | ThI4 | PaI4
PaI5 | UI3
UI4 | NpI3 | PuI3 | AmI2
AmI3 | CmI3 | BkI
3 | CfI

CfI
3 | EsI3 | Fm  | Md  | No
*[CID]: Compound ID
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