Niobium(III) chloride - Misplaced Pages

Niobium(III) chloride
Identifiers
CAS Number	13569-59-0
3D model (JSmol)	Interactive image 1,2-dimethoxyethane complex: Interactive image
ChemSpider	75410
ECHA InfoCard	100.033.608
EC Number	236-985-0
PubChem CID	11542954 1,2-dimethoxyethane complex: 6096194
CompTox Dashboard (EPA)	DTXSID3065536
InChI InChI=1S/3ClH.Nb/h31H;/q;;;+3/p-3Key: VPDYSPXEGTXWEU-UHFFFAOYSA-K 1,2-dimethoxyethane complex: InChI=1S/C4H10O2.3ClH.Nb/c1-5-3-4-6-2;;;;/h3-4H2,1-2H3;31H;/q;;;;+3/p-3Key: SBSZUBUHOUKQMN-UHFFFAOYSA-K
SMILES ... 1,2-dimethoxyethane complex: COCCOC.Cl(Cl)Cl
Properties
Chemical formula	Cl₃Nb
Molar mass	199.26 g·mol
Appearance	black solid
Density	3.75
Structure
Crystal structure	hexagonal
Space group	P3m1
Lattice constant	a = 6.744, c = 12.268
Formula units (Z)	2
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references

Chemical compound

Niobium(III) chloride also known as niobium trichloride is a compound of niobium and chlorine. The binary phase NbCl₃ is not well characterized but many adducts are known.

Synthesis

Structure of NbCl₃(dimethoxyethane)(3-hexyne).

Nb₃Cl₈ is produced by reduction of niobium(V) chloride with hydrogen, or just by heating.

Salt-free reduction of dimethoxyethane solution of NbCl₅ with 1,4-disilyl-cyclohexadiene in the presence of 3-hexyne produces the coordination complex NbCl₃(dimethoxyethane)(3-hexyne):

NbCl₅ + C₆H₆(SiMe₃)₂ + C₂Et₂ + dme → NbCl₃(dme)(C₂Et₂) + C₆H₆ + 2 Me₃SiCl

An impure dimethoxyethane (dme) adduct of niobium trichloride was produced by reduction of a dme solution of niobium pentachloride with tributyltin hydride:

NbCl₅ + 2 Bu₃SnH + MeOCH₂CH₂OMe → NbCl₃(MeOCH₂CH₂OMe) + 2 Bu₃SnCl

Structure

Nb₃Cl₈ has a hexagonal close packed array of chloride ions. Triangles of niobium occur in octahedral spaces in the chloride array. The compositions with higher chloride have some niobium atoms missing from the structure, creating vacancies and giving rise to nonstoichiometric compounds. NbCl₄ has this pattern of vacancies stretched until the niobium atoms are in pairs rather than triangles. So NbCl₃ can be considered as a solid solution of Nb₃Cl₈ and Nb₂Cl₈.

The colour of niobium trichloride varies depending on the niobium:chloride ratio. NbCl_2.67 is green, while NbCl_3.13 is brown.

Reactions

When heated to over 600 °C niobium trichloride disproportionates to niobium metal and niobium pentachloride.

Adducts

NbCl₃(dimethoxyethane) has received significant attention as a reagent for reductive coupling of carbonyls and imines. It is sold as a 1,2-dimethoxyethane complex. Nb(III) adducts are also known for 1,4-dioxane and diethyl ether.

Niobium(III) chloride forms a series of compounds with the formula Nb₂Cl₆L_x with Nb=Nb double bond. With tertiary phosphines and arsines, the complexes are edge-share bioctahedra, e.g., Nb₂Cl₆(PPhMe₂)₄. Thioethers form adducts with one bridging thioether (R₂S). These face-sharing bioctahedra have the formula Nb₂X₆(R₂S)₃ (X = Cl, Br).

References

^ Gutmann, Viktor (1967). Halogen Chemistry. Elsevier. p. 157. ISBN 978-0-323-14847-4.
Tsurugi, Hayato; Mashima, Kazushi (2019). "Salt-Free Reduction of Transition Metal Complexes by Bis(trimethylsilyl)cyclohexadiene, -dihydropyrazine, and -4,4′-bipyridinylidene Derivatives". Accounts of Chemical Research. 52 (3): 769–779. doi:10.1021/acs.accounts.8b00638. PMID 30794373. S2CID 73505603.
Pedersen, Steven F.; Hartung, Jack B.; Roskamp, Eric J.; Dragovich, Peter S. (1992). "Niobium(III) and (IV) Halide Complexes". Inorganic Syntheses. Vol. 28. pp. 119–123. doi:10.1002/9780470132609.ch28. ISBN 9780470132609.
Cotton, F. Albert; Wilkinson, Geoffrey (1966). Advanced Inorganic Chemistry: A Comprehensive Text. John Wiley. p. 927.
Kakeya, Masaki; Fujihara, Takashi; Nagasawa, Akira (2006). "Di-μ-chloro-μ-(dimethyl sulfide)-bis[dichloro(dimethyl sulfide)niobium(III)]". Acta Crystallographica Section E. 62 (3): m553 – m554. Bibcode:2006AcCrE..62M.553K. doi:10.1107/S1600536806005149.
Roskamp, Carrie A.; Roskamp, Eric J. (2001). "Trichloro(1,2-dimethoxyethane)niobium". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt202s. ISBN 0471936235.
Sharma, Sangeeta; Vermani, O. P.; Narula, A. K. (January 1996). "Synthesis and Structural Studies of Complexes of Niobium(III) Chloride with Ditertiary Phosphines". Indian Journal of Chemistry, Section A. 35A (1). ISSN 0975-0975.