Isocyanide Ligation Enables Electrochemical Ammonia Formation in a Synthetic Cycle for N Fixation.

Transition-metal-mediated splitting of N to form metal nitride complexes could constitute a key step in electrocatalytic nitrogen fixation, if these nitrides can be electrochemically reduced to ammonia under mild conditions. The envisioned nitrogen fixation cycle involves several steps: N binding to form a dinuclear end-on bridging complex with appropriate electronic structure to cleave the N bridge followed by proton/electron transfer to release ammonia and bind another molecule of N. The nitride reduction and N splitting steps in this cycle have differing electronic demands that a catalyst must satisfy.

Facile conversion of ammonia to a nitride in a rhenium system that cleaves dinitrogen.

Rhenium complexes with aliphatic PNP pincer ligands have been shown to be capable of reductive N splitting to nitride complexes. However, the conversion of the resulting nitride to ammonia has not been observed. Here, the thermodynamics and mechanism of the hypothetical N-H bond forming steps are evaluated through the reverse reaction, conversion of ammonia to the nitride complex.

Electronic and Spin-State Effects on Dinitrogen Splitting to Nitrides in a Rhenium Pincer System.

Bimetallic nitrogen (N) splitting to form metal nitrides is an attractive method for N fixation. Although a growing number of pincer-supported systems can bind and split N, the precise relationship between the ligand properties and N binding/splitting remains elusive. Here we report the first example of an N-bridged rhenium(III) complex, [(-PPyrr)ReCl](μ-η:η-N) (PPyrr = [2,5-(CHPBu)CHN]).

Luminescence of Lanthanide Complexes with Perfluorinated Alkoxide Ligands.

Four groups of rare-earth complexes, comprising 11 new compounds, with fluorinated O-donor ligands ([K(THF)][Ln(OCF)(THF)] (; Ln = Ce, Nd), [K](THF)[Ln(OCF)(THF)] (; Ln = Eu, Gd, Dy), [K(THF)][Ln(pin)(THF)] (; Ln = Ce, Nd), and [K(THF)][Ln(pin)(THF)] (; Ln = Eu, Gd, Dy, Y) have been synthesized and characterized. Single-crystal X-ray diffraction data were collected for all compounds except . Species , , and are uncommon examples of six-coordinate (Eu, Gd, Dy, and Y) and seven-coordinate (Ce and Nd) Ln centers in all-O-donor environments.