Photoswitchable Metal-Mediated Catalysis: Remotely Tuned Alkene and Alkyne Hydroborations

A photochromic dithienylethene-annulated N-heterocyclic carbene (NHC)–Rh(I) complex was synthesized and found to undergo reversible electrocyclic ring closure upon alternate exposure to UV (λirr 313 nm) and visible (λirr >500 nm) radiation. Under ambient light, the Rh catalyst efficiently promote...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:Organometallics 2013-05, Vol.32 (10), p.3121-3128
Hauptverfasser: Neilson, Bethany M, Bielawski, Christopher W
Format: Artikel
Sprache:eng
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:A photochromic dithienylethene-annulated N-heterocyclic carbene (NHC)–Rh(I) complex was synthesized and found to undergo reversible electrocyclic ring closure upon alternate exposure to UV (λirr 313 nm) and visible (λirr >500 nm) radiation. Under ambient light, the Rh catalyst efficiently promoted the hydroboration of alkenes and alkynes with pinacolborane. However, upon UV irradiation to effect a photocyclization within the NHC ligand, the catalytic activity was reduced by up to an order of magnitude. The disparity in the rates was used to photoswitch the rates of a series of hydroboration reactions, thus demonstrating the first examples of photomodulating a transition-metal catalyst by tuning its electronic properties. The rate attenuation observed under UV irradiation was attributed to inhibition of the rate-determining reductive elimination step arising from a decrease in electron-donating ability of the photocyclized NHC ligated to the Rh center.
ISSN:0276-7333
1520-6041
DOI:10.1021/om400348h