Metal-Ligand Cooperative Synthesis of Benzonitrile by Electrochemical Reduction and Photolytic Splitting of Dinitrogen.

Thermal nitrogen fixation relies on strong reductants to overcome the extraordinarily large N-N bond energy. Photochemical strategies that drive N fixation are scarcely developed. Here, the synthesis of a dinuclear N -bridged complex is presented upon reduction of a rhenium(III) pincer platform.

Mechanism of Chemical and Electrochemical N Splitting by a Rhenium Pincer Complex.

A comprehensive mechanistic study of N activation and splitting into terminal nitride ligands upon reduction of the rhenium dichloride complex [ReCl(PNP)] is presented (PNP = N(CHCHP tBu)). Low-temperature studies using chemical reductants enabled full characterization of the N-bridged intermediate [{(PNP)ClRe}(N)] and kinetic analysis of the N-N bond scission process. Controlled potential electrolysis at room temperature also resulted in formation of the nitride product [Re(N)Cl(PNP)].

Photochemically Driven Reverse Water-Gas Shift at Ambient Conditions mediated by a Nickel Pincer Complex.

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.

A Terminal Osmium(IV) Nitride: Ammonia Formation and Ambiphilic Reactivity.

Low-valent osmium nitrides are discussed as intermediates in nitrogen fixation schemes. However, rational synthetic routes that lead to isolable examples are currently unknown. Here, the synthesis of the square-planar osmium(IV) nitride [OsN(PNP)] (PNP=N(CH2 CH2 P(tBu)2 )2 ) is reported upon reversible deprotonation of osmium(VI) hydride [Os(N)H(PNP)](+) .