Niobium(III) chloride

Niobium(III) chloride
Identifiers
CAS Number	13569-59-0;
3D model (JSmol)	Interactive image; 1,2-dimethoxyethane complex: Interactive image;
ChemSpider	75410;
PubChem CID	11542954; 1,2-dimethoxyethane complex: 6096194;
	InChI InChI=1S/3ClH.Nb/h31H;/q;;;+3/p-3 Key: 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-3 Key: SBSZUBUHOUKQMN-UHFFFAOYSA-K;
	SMILES [Cl-].[Cl-].[Cl-].[Nb+3]; 1,2-dimethoxyethane complex: COCCOC.Cl[Nb](Cl)Cl;
Properties
Chemical formula	Cl3Nb
Molar mass	199.26 g·mol−1
Appearance	black solid
Density	3.75
Structure[1]
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 [77 °F], 100 kPa).
	Infobox references

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).[2]

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

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:[3]

NbCl₅ + 2 Bu₃SnH + CH₃OCH₂CH₂OCH₃ → NbCl₃(CH₃OCH₂CH₂OCH₃) + 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. 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.[4] The triangles of Nb₃ and pairs Nb₂ in these solid compounds are niobium clusters.

Properties

The colour of niobium trichloride varies depending on the chloride ratio from green for NbCl_2.67 to brown for NbCl_3.13.[1]

Reactions

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

NbCl₃(dimethoxyethane) has received significant attention as a reagent for reductive coupling of carbonyls and imines.[5]

Niobium(III) chloride forms many molecular complexes with tertiary phosphines.[6] It is sold as a 1,2-dimethoxyethane complex.

Niobium(III) chloride, in the form of Nb₂Cl₆ with ligands, is also a metal cluster compound with a double bond between the two niobium atoms. Some known complexes have the following formulae: Nb₂Cl₆(Me₂S)₃, Nb₂Cl₆(PPhMe₂)₄, Nb₂Cl₆[o-(AsMe₂)₂C₆H₄]₂ (diars), Nb₂Cl₆[MeC(CH₂AsMe₂)₃]₂ (triars), Nb₂Cl₆[Ph₂PCH₂CH₂PPh₂]₄ (diphos), Nb₂Cl₆[PhPMe₂]₄, and yet other ligands such as 1,4-dioxane, diethyl ether, or the crown thioether (SC₄H₈)₃ (which is violet).[7]

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References

Gutmann, Viktor (1967). Halogen Chemistry. Elsevier. p. 157. ISBN 978-0-323-14847-4.
Arteaga-Müller, Rocío; Tsurugi, Hayato; Saito, Teruhiko; Yanagawa, Masao; Oda, Seiji; Mashima, Kazushi (2009). "New Tantalum Ligand-Free Catalyst System for Highly Selective Trimerization of Ethylene Affording 1-Hexene: New Evidence of a Metallacycle Mechanism". Journal of the American Chemical Society. 131 (15): 5370–5371. doi:10.1021/ja8100837. PMID 20560633.
Pedersen, Steven F.; Hartung, Jack B.; Roskamp, Eric J.; Dragovich, Peter S. (1992). "Niobium(III) and (IV) Halide Complexes". Inorganic Syntheses. 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.
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.
Hagen, A. P. (2009). Inorganic Reactions and Methods, The Formation of Bonds to Transition and Inner-Transition Metals. John Wiley & Sons. pp. 67–69. ISBN 978-0-470-14550-0.

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[gut-1] Gutmann, Viktor (1967). Halogen Chemistry. Elsevier. p. 157. ISBN 978-0-323-14847-4.

[2] Arteaga-Müller, Rocío; Tsurugi, Hayato; Saito, Teruhiko; Yanagawa, Masao; Oda, Seiji; Mashima, Kazushi (2009). "New Tantalum Ligand-Free Catalyst System for Highly Selective Trimerization of Ethylene Affording 1-Hexene: New Evidence of a Metallacycle Mechanism". Journal of the American Chemical Society. 131 (15): 5370–5371. doi:10.1021/ja8100837. PMID 20560633.

[3] Pedersen, Steven F.; Hartung, Jack B.; Roskamp, Eric J.; Dragovich, Peter S. (1992). "Niobium(III) and (IV) Halide Complexes". Inorganic Syntheses. 28. pp. 119–123. doi:10.1002/9780470132609.ch28. ISBN 9780470132609.

[4] Cotton, F. Albert; Wilkinson, Geoffrey (1966). Advanced Inorganic Chemistry: A Comprehensive Text. John Wiley. p. 927.

[5] 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.

[6] 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.

[7] Hagen, A. P. (2009). Inorganic Reactions and Methods, The Formation of Bonds to Transition and Inner-Transition Metals. John Wiley & Sons. pp. 67–69. ISBN 978-0-470-14550-0.