Niobium(IV) Chloride


[13569-70-5]  · Cl4Nb  · Niobium(IV) Chloride  · (MW 234.71) (NbCl4(THF)2)

[61247-55-2]  · C8H16Cl4NbO2  · Niobium(IV) Chloride  · (MW 378.95)

(reductively couples imines and nitriles1)

Physical Data: NbCl4: subl. 200 °C/10-4 mmHg. NbCl4(THF)2: mp 110 °C (dec), yellow crystals.

Solubility: sol ethereal and thioether solvents.

Form Supplied in: not commercially available.

Preparative Method: tetrachlorobis(tetrahydrofuran)niobium is prepared from commercially available niobium(V) chloride in two steps.2

Purification: filter and wash with THF and dry under vacuum.

Handling, Storage, and Precautions: corrosive; moisture sensitive. Use in a fume hood.

Reductive Coupling of N-Silylimines and Nitriles.

Treatment of N-silylimines with niobium(IV) chloride leads to 1,2-diamines (eq 1). The reaction is the nitrogen analog of the pinacol coupling reaction. The reaction produces initially the bis(metal imido) complex, which is hydrolyzed to the corresponding diamine by reaction with aqueous Potassium Hydroxide. Alternatively, reaction of nitriles, Tri-n-butylchlorostannane, and niobium(IV) chloride produces a similar coupling product (eq 2). Both aryl- and alkyl-substituted imines are suitable substrates for the reaction. Predominantly the (±)-isomer is produced in the coupling reaction; however, the selectivity is considerably greater when imines derived from aryl aldehydes are employed in the reaction.

Related Reagents.

Niobium(V) Chloride-Zinc; Samarium(II) Iodide; Titanium(III) Chloride.

1. Roskamp, E. J.; Pedersen, S. F. JACS 1987, 109, 3152.
2. Manzer, L. E. IC 1977, 16, 525.

James W. Herndon

University of Maryland, College Park, MD, USA

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