Jump to main content
Jump to site search

Issue 42, 2020

1,2-Addition and cycloaddition reactions of niobium bis(imido) and oxo imido complexes

Author affiliations

Abstract

The bis(imido) complexes (BDI)Nb(NtBu)2 and (BDI)Nb(NtBu)(NAr) (BDI = N,N′-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate; Ar = 2,6-diisopropylphenyl) were shown to engage in 1,2-addition and [2 + 2] cycloaddition reactions with a wide variety of substrates. Reaction of the bis(imido) complexes with dihydrogen, silanes, and boranes yielded hydrido-amido-imido complexes via 1,2-addition across Nb-imido π-bonds; some of these complexes were shown to further react via insertion of carbon dioxide to give formate-amido-imido products. Similarly, reaction of (BDI)Nb(NtBu)2 with tert-butylacetylene yielded an acetylide-amido-imido complex. In contrast to these results, many related mono(imido) Nb BDI complexes do not exhibit 1,2-addition reactivity, suggesting that π-loading plays an important role in activating the Nb–N π-bonds toward addition. The same bis(imido) complexes were also shown to engage in [2 + 2] cycloaddition reactions with oxygen- and sulfur-containing heteroallenes to give carbamate- and thiocarbamate-imido complexes: some of these complexes readily dimerized to give bis-μ-sulfido, bis-μ-iminodicarboxylate, and bis-μ-carbonate complexes. The mononuclear carbamate imido complex (BDI)Nb(NAr)(N(tBu)CO2) (12) could be induced to eject tert-butylisocyanate to generate a four-coordinate terminal oxo imido intermediate, which could be trapped as the five-coordinate pyridine or DMAP adduct. The DMAP adducted oxo imido complex (BDI)NbO(NAr)(DMAP) (16) was shown to engage in 1,2-addition of silanes across the Nb-oxo π-bond; this represents a new reaction pathway in group 5 chemistry.

Graphical abstract: 1,2-Addition and cycloaddition reactions of niobium bis(imido) and oxo imido complexes

Supplementary files

Article information


Submitted
23 Jun 2020
Accepted
28 Sep 2020
First published
09 Oct 2020

This article is Open Access
All publication charges for this article have been paid for by the Royal Society of Chemistry

Chem. Sci., 2020,11, 11613-11632
Article type
Edge Article

1,2-Addition and cycloaddition reactions of niobium bis(imido) and oxo imido complexes

J. I. Fostvedt, L. N. Grant, B. M. Kriegel, A. H. Obenhuber, T. D. Lohrey, R. G. Bergman and J. Arnold, Chem. Sci., 2020, 11, 11613 DOI: 10.1039/D0SC03489D

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.


Social activity

Search articles by author

Spotlight

Advertisements