Hafnium(Iii) Iodide

Hafnium(III) iodide
Names
	IUPAC name Hafnium triiodide
Identifiers
CAS Number	13779-73-2 ;
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
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

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

Preparation

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 I_3.2–3.3 and Hf I_3.0–3.5 reported.^[3]^[4]

Structure and bonding

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

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

↑ William M. Haynes, ed (2013). CRC Handbook of Chemistry and Physics (93rd ed.). CRC Press. p. 4–66. ISBN 978-1466571143.
↑ ^2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 965. ISBN 978-0-08-037941-8.
↑ ^3.0 ^3.1 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.
↑ 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.
↑ ^5.0 ^5.1 Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. pp. 418–419. ISBN 978-0-19-965763-6.
↑ 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.

HI																	He
LiI	BeI₂											BI₃	CI₄	NI₃	I₂O₄, I₂O₅, I₄O₉	IF, IF₃, IF₅, IF₇	Ne
NaI	MgI₂											AlI₃	SiI₄	PI₃, P₂I₄	S	ICl, ICl₃	Ar
KI	CaI₂	Sc	TiI₄	VI₃	CrI₃	MnI₂	FeI₂	CoI₂	NiI₂	CuI	ZnI₂	Ga₂I₆	GeI₂, GeI₄	AsI₃	Se	IBr	Kr
RbI	SrI₂	YI₃	ZrI₄	NbI₅	Mo	Tc	Ru	Rh	Pd	AgI	CdI₂	InI₃	SnI₄, SnI₂	SbI₃	TeI₄	I	Xe
CsI	BaI₂		HfI₄	TaI₅	W	Re	Os	Ir	Pt	AuI	Hg₂I₂, HgI₂	TlI	PbI₂	BiI₃	Po	AtI	Rn
Fr	RaI₂		Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Nh	Fl	Mc	Lv	Ts	Og
		↓
		La	Ce	Pr	Nd	Pm	SmI₂	Eu	Gd	TbI₃	Dy	Ho	Er	Tm	Yb	Lu
		Ac	ThI₄	Pa	UI₃, UI₄	Np	Pu	Am	Cm	Bk	Cf	EsI₃	Fm	Md	No	Lr

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Original source: https://en.wikipedia.org/wiki/Hafnium(III) iodide. Read more

[1] William M. Haynes, ed (2013). CRC Handbook of Chemistry and Physics (93rd ed.). CRC Press. p. 4–66. ISBN 978-1466571143.

[G&E-2] 2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 965. ISBN 978-0-08-037941-8.

[Struss-3] 3.0 ^3.1 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.

[Clark-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.

[Wells-5] 5.0 ^5.1 Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. pp. 418–419. ISBN 978-0-19-965763-6.

[Dahl-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(IV)	HfC HfBr₄ HfCl₄ HfF₄ HfI₄ Hf(C₅H₇O₂)₄ HfO₂ HfSiO₄ HfS₂ Ta₄HfC₅