Photolytic activation of late-transition-metal-carbon bonds and their reactivity toward oxygen
File(s)
Accepted version
Supporting information
Author(s)
Type
Journal Article
Abstract
The photolytic activation of palladium(II) and platinum(II) complexes [M(BPI)(R)] (R = alkyl, aryl) featuring the 1,3-bis(2-pyridylimino)isoindole (BPI) ligand has been investigated in various solvents. In the absence of oxygen, the formation of chloro complexes [M(BPI)Cl] is observed in chlorinated solvents, most likely due to the photolytic degradation of the solvent and formation of HCl. The reactivity of the complexes toward oxygen has been studied both experimentally and computationally. Excitation by UV irradiation (365 nm) of the metal complexes [Pt(BPI)Me] and [Pd(BPI)Me] leads to distortion of the square-planar coordination geometry in the excited triplet state and a change in the electronic structure of the complexes that allows the interaction with oxygen. TD-DFT computational studies suggest that, in the case of palladium, the Pd(III) superoxide intermediate [Pd(BPI)(κ1-O2)Me] is formed and, in the case of platinum, the Pt(IV) peroxide intermediate [Pt(BPI)(κ2-O2)Me]. For alkyl complexes where metal–carbon bonds are sufficiently weak, the photoactivation leads to the insertion of oxygen into the metal–carbon bond to generate alkylperoxo complexes: for example [Pd(BPI)OOMe], which has been isolated and structurally characterized. For stronger M–C(aryl) bonds, the reaction of [Pt(BPI)Ph] with O2 and light results in a Pt(IV) complex, tentatively assigned as the peroxo complex [Pt(BPI)(κ2-O2)Ph], which in chlorinated solvents reacts further to give [Pt(BPI)Cl2Ph], which has been isolated and characterized by scXRD. In addition to the facilitation of oxygen insertion reactions, UV irradiation can also affect the reactivity of other components in the reaction mixture, such as the solvent or other reaction products, which can result in further reactions. Labeling studies using [Pt(BPI)(CD3)] in chloroform have shown that photolytic reactions with oxygen involve degradation of the solvent.
Date Issued
2021-12-08
Date Acceptance
2021-12-01
Citation
Organometallics, 2021, 40 (24), pp.4077-4091
ISSN
0276-7333
Publisher
American Chemical Society
Start Page
4077
End Page
4091
Journal / Book Title
Organometallics
Volume
40
Issue
24
Copyright Statement
Copyright © 2021 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in [JournalTitle], after peer review and technical editing by the publisher. To access the final edited and published work see [insert hyperlinked DOI, see ACS Articles on Request https://pubs.acs.org/page/4authors/benefits/index.html#articles-request]
Identifier
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Subjects
Science & Technology
Physical Sciences
Chemistry, Inorganic & Nuclear
Chemistry, Organic
Chemistry
HX-REDUCTIVE-ELIMINATION
MOLECULAR-OXYGEN
OXIDATIVE ADDITION
DIOXYGEN INSERTION
PINCER COMPLEXES
O-2 ACTIVATION
C-C
PLATINUM(II)
MECHANISM
ALKYL
Publication Status
Published
Date Publish Online
2021-12-08