Despite the continuing popularity of radical reactions in organic synthesis, much remains to be explored in this area. Herein, we describe how spatiotemporal control can be exerted over the formation and reactivity of divergent exchangeable formamide radicals using nickel complexes with a semiconductor material (TiO<sub>2</sub>) under irradiation from near-UV–Vis light. Depending on the bipyridine ligand used and the quantity of the nickel complex that is hybridized on or nonhydridized over the TiO<sub>2</sub> surface, these radicals selectively undergo substitution reactions at the carbon center of carbon–bromine bonds that proceed via three different pathways. As the scalable production of formamides from CO<sub>2</sub> does not produce salt waste, these methods could add a new dimension to the search for carbon neutrality through the indirect incorporation of CO<sub>2</sub> into organic frameworks.
Synthesis
and characterisation of one trinuclear copper complex, ([Cu<sub>3</sub>L<sub>3</sub>O]ClO<sub>4</sub>)
(<b>1</b>) and one nickel complex ([Ni(L'H)<sub>2</sub>(dmso)<sub>2</sub>](ClO<sub>4</sub>)<sub>2</sub>)
(<b>2</b>) with Schiff base ligands: (3Z)-3-((Z)-(1-(thiophen-2-yl)ethylidene)hydrazono)butan-2-one
oxime (LH) and 1-(pyridin-2-yl)ethylidene)hydrazono)butan-2-one
oxime (L<sup>'</sup>H). <b>1</b> shows high catecholase activity and has also been tested as a
catalyst for the synthesis of benzylimine. <b>2 </b> shows phenoxazinone synthase activity.
A robust tetrameric nickel complex [Ni4((Oal−)2L-Me)4(s)4] (s = solvent) with cubane-like Ni4O4 core topology identified as the efficient catalyst for the diastereoselective cyclopropanation of aromatic heterocycles.
The availability of polymorphs of metallic complexes provides an opportunity to reveal the relationship between crystal packing and catalytic activity. Herein, we immobilize two stable concomitant polymorphs (green NiL2-G and...
The reaction of N-heteroaromatic compounds, such as 2-aryl-pyrrole, benzimidazole, imidazole, indole, and pyrazole derivatives, with alkynes in the presence of a catalytic amount of a nickel complex results in C–H/N–H oxidative annulation.
Synthesis, oligomerization and catalytic studies of a redox-active Ni4-cubane: a detailed mechanistic investigation
