s-Block metal complexes of superbulky (tBu3Si)2N-: a new weakly coordinating anion?

Knüpfer C, Klerner L, Mai J, Langer J, Harder S (2024)

Publication Type: Journal article

Publication year: 2024

Journal

Chemical Science Royal Society of Chemistry

DOI: 10.1039/d3sc06896j

Abstract

Sterically hindered amide anions have found widespread application as deprotonation agents or as ligands to stabilize metals in unusual coordination geometries or oxidation states. The use of bulky amides has also been advantageous in catalyst design. Herein we present s-block metal chemistry with one of the bulkiest known amide ligands: (tBu3Si)2N- (abbreviated: tBuN-). The parent amine (tBuNH), introduced earlier by Wiberg, is extremely resistant to deprotonation (even with nBuLi/KOtBu superbases) but can be deprotonated slowly with a blue Cs+/e- electride formed by addition of Cs0 to THF. (tBuN)Cs crystallized as a separated ion-pair, even without cocrystallized solvent. As salt-metathesis reactions with (tBuN)Cs are sluggish and incomplete, it has only limited use as an amide transfer reagent. However, ball-milling with LiI led to quantitative formation of (tBuN)Li and CsI. Structural characterization shows that (tBuN)Li is a monomeric contact ion-pair with a relatively short N-Li bond, an unusual T-shaped coordination geometry around N and extremely short Li?Me anagostic interactions. Crystal structures are compared with Li and Cs complexes of less bulky amide ligands (iPr3Si)2N- (iPrN-) and (Me3Si)2N- (MeN-). DFT calculations show trends in the geometries and electron distributions of amide ligands of increasing steric bulk (MeN- < iPrN- < tBuN-) and confirm that tBuN- is a rare example of a halogen-free weakly coordinating anion.

Authors with CRIS profile

Christian Knüpfer Lehrstuhl für Anorganische und Metallorganische Chemie Lukas Klerner Lehrstuhl für Anorganische und Metallorganische Chemie Jonathan Mai Lehrstuhl für Anorganische und Metallorganische Chemie Jens Langer Lehrstuhl für Anorganische und Metallorganische Chemie Sjoerd Harder Lehrstuhl für Anorganische und Metallorganische Chemie

How to cite

APA:

Knüpfer, C., Klerner, L., Mai, J., Langer, J., & Harder, S. (2024). s-Block metal complexes of superbulky (tBu3Si)2N-: a new weakly coordinating anion? Chemical Science. https://doi.org/10.1039/d3sc06896j

MLA:

Knüpfer, Christian, et al. "s-Block metal complexes of superbulky (tBu3Si)2N-: a new weakly coordinating anion?" Chemical Science (2024).

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