9-Fluorenone acts as a metal-free and additive-free photocatalyst for the selective oxidation of primary and secondary alcohols under visible light. With this photocatalyst, a plethora of alcohols such as aliphatic, heteroaromatic, aromatic, and alicyclic compounds has been converted to the corresponding carbonyl compounds using air/oxygen as an oxidant. In addition to these, several steroids have been oxidized to the corresponding carbonyl compounds. Detailed mechanistic studies have also been achieved to determine the role of the oxidant and the photocatalyst for this oxidation.

A mild protocol has been developed using polymeric carbon nitrides (PCN) as metal-free heterogeneous photocatalyst to convert olefins into the corresponding carbonyls which even can be applied in the gram scale synthesis using direct solar energy.

The endothermic reverse water-gas shift reaction (rWGS) for direct CO hydrogenation to CO is an attractive approach to carbon utilization. However, direct CO hydrogenation with molecular catalysts generally gives formic acid instead of CO as a result of the selectivity of CO insertion into M-H bonds. Based on the photochemical inversion of this selectivity, several synthetic pathways are presented for CO selective CO reduction with a nickel pincer platform including the first example of a photodriven rWGS cycle at ambient conditions.

Hydrierung S. Schneider et al. präsentieren in der Zuschrift auf S. 14690 ff. eine reverse Wassergas‐Shift‐Reaktion, die durch ein molekulares Nickelhydrid vermittelt wird. Diese durch Licht angetriebene Reaktion verläuft unter Umgebungsbedingungen.

The endothermic reverse water‐gas shift reaction (rWGS) for direct CO2 hydrogenation to CO is an attractive approach to carbon utilization. However, direct CO2 hydrogenation with molecular catalysts generally gives formic acid instead of CO as a result of the selectivity of CO2 insertion into M−H bonds. Based on the photochemical inversion of this selectivity, several synthetic pathways are presented for CO selective CO2 reduction with a nickel pincer platform including the first example of a photodriven rWGS cycle at ambient conditions.