NbCl3(dme) provides a convenient gateway into niobium(III) complexes. Due to its d2 configuration, it tends to exhibit Lewis basic behavior towards pi-ligands such as olefins. These types of complexes have found use in reductive couplings of amines and carbonyls, pyrrole synthesis, conversion of aldehydes into 1,2-diols, and reduction of alkynes to cis-alkenes.[1] The complex can be conveniently synthesized via reduction of the niobium(V) precursor with trimethyltin hydride in the presence of dimethoxyethane, according to an air/moisture-free 1992 Inorganic Syntheses procedure.[2]
Notes:
- NbCl3(dme) is an air/moisture sensitive red solid soluble in polar organic solvents. It is stable indefinitely at room temperature when stored in the glovebox.
- NbCl5 starting material is moisture sensitive. It can be prepared from niobium oxide hydrate and thionyl chloride.[3]
- Anhydrous dimethoxyethane can be purchased from chemical vendors (Millipore-Sigma, VWR, Fisher Scientific). It can also be dried with molecular sieves and distilled (to remove inhibitor) prior to use. Dimethoxyethane forms peroxides over time when exposed to air. For a nice list of peroxide-forming routine chemicals, see the document below from University of Louisville:
Peroxide-Forming Chemicals Guide
or a more comprehensive list from UC Santa Cruz:
Classification List of Peroxide Forming Chemicals - Careful when handling tributyltin hydride. It is toxic and readily absorbed upon contact with skin, as expected of organotin compounds.
[1] Roskamp, C. A. Trichloro(1,2-dimethoxyethane)niobium. EROS, 2001. DOI: 10.1002/047084289X.rt202s.
[2] Pedersen, S. F.; Hartung, J. B.; Roskamp, E. J.; Dragovich, P. S. Niobium(III) and (IV) Halide Complexes. Inorg. Synth . 1992, 28, 119–123. DOI: 10.1002/9780470132609.ch28.
[3] Brown, D.; Cavell, R. G. Niobium(V) Chloride and Hexachloroniobates(V). Inorg. Synth. 1967, 9, 88-92.