skip to main content

Attention:

The NSF Public Access Repository (PAR) system and access will be unavailable from 11:00 PM ET on Friday, December 13 until 2:00 AM ET on Saturday, December 14 due to maintenance. We apologize for the inconvenience.


Search for: All records

Creators/Authors contains: "Cheisson, Thibault"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. The separation and purification of niobium and tantalum, which co-occur in natural sources, is difficult due to their similar physical and chemical properties. The current industrial method for separating Ta/Nb mixtures uses an energy-intensive process with caustic and toxic conditions. It is of interest to develop alternative, fundamental methodologies for the purification of these technologically important metals that improve upon their environmental impact. Herein, we introduce new Ta/Nb imido compounds: M( t BuN)(TriNOx) (1-M) bound by the TriNOx 3− ligand and demonstrate a fundamental, proof-of-concept Ta/Nb separation based on differences in the imido reactivities. Despite the nearly identical structures of 1-M, density functional theory (DFT)-computed electronic structures of 1-M indicate enhanced basic character of the imido group in 1-Ta as compared to 1-Nb. Accordingly, the rate of CO 2 insertion into the MN imido bond of 1-Ta to form a carbamate complex (2-Ta) was selective compared to the analogous, unobserved reaction with 1-Nb. Differences in solubility between the imido and carbamate complexes allowed for separation of the carbamate complex, and led to an efficient Ta/Nb separation ( S Ta/Nb = 404 ± 150) dependent on the kinetic differences in nucleophilicities between the imido moieties in 1-Ta and 1-Nb. 
    more » « less
  2. null (Ed.)
    The reactivity of alkali metal capped Ce( iv ) imido compounds [M(DME) 2 ][CeNAr F (TriNOx)] ( 1-M with M = K, Rb, Cs and Ar F = 3,5-bis(trifluoromethyl)phenyl) with CO 2 and organic isocyanates has been evaluated. 1-Cs reacted with CO 2 to yield an organocarbamate complex. Reaction of 1-K and 1-Rb with organic isocyanates yielded organoureate Ce( iv ) complexes. 
    more » « less