Issue 11, 2017

Synthesis of a terminal Ce(iv) oxo complex by photolysis of a Ce(iii) nitrate complex

Abstract

Reaction of [Ce(NR2)3] (R = SiMe3) with LiNO3 in THF, in the presence of 2,2,2-cryptand, results in the formation of the Ce(III) “ate” complex, [Li(2,2,2-cryptand)][Ce(κ2-O2NO)(NR2)3] (1) in 38% yield. Photolysis of 1 at 380 nm affords [Li(2,2,2-cryptand)][Ce(O)(NR2)3] (2), in 33% isolated yield after reaction work-up. Complex 2 is the first reported example of a Ce(IV) oxo complex where the oxo ligand is not supported by hydrogen bonding or alkali metal coordination. Also formed during photolysis are [Li(2,2,2-cryptand)]2[(μ3-O){Ce(μ-O)(NR2)2}3] (3) and [Li(2,2,2-cryptand)][Ce(OSiMe3)(NR2)3] (4). Their identities were confirmed by X-ray crystallography. Complex 4 can also be prepared via reaction of [Ce(NR2)3] with LiOSiMe3 in THF, in the presence of 2,2,2-cryptand. When synthesized in this fashion, 4 can be isolated in 47% yield. To rationalize the presence of 2, 3, and 4 in the reaction mixture, we propose that photolysis of 1 first generates 2 and NO2, via homolytic cleavage of the N–O bond in its nitrate co-ligand. Complex 2 then undergoes decomposition via two separate routes: (1) ligand scrambling and oligomerization to form 3; and, (2) abstraction of a trimethylsilyl cation to form a transient Ce(IV) silyloxide, [CeIV(OSiMe3)(NR2)3], followed by 1e reduction to form 4. Alternatively, complex 4 could form directly via ·SiMe3 abstraction by 2.

Graphical abstract: Synthesis of a terminal Ce(iv) oxo complex by photolysis of a Ce(iii) nitrate complex

Supplementary files

Article information

Article type
Edge Article
Submitted
24 Aug 2017
Accepted
27 Sep 2017
First published
27 Sep 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2017,8, 7873-7878

Synthesis of a terminal Ce(IV) oxo complex by photolysis of a Ce(III) nitrate complex

M. K. Assefa, G. Wu and T. W. Hayton, Chem. Sci., 2017, 8, 7873 DOI: 10.1039/C7SC03715E

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