Nitrogen fixation and transformation with main group elements

Abstract

In this tutorial, we introduced the fundamental aspects of nitrogen fixation, summarized the recent progresses with main group elements and tried to make clear the clue for further developments.

Reductive activation of N2 using a calcium/potassium bimetallic system supported by an extremely bulky diamide ligand

“…This lack of reactivity arises from the extremely strong triple bond of the non-polar molecule (bond dissociation energy = 944 kJ mol −1 ), and its large HOMO–LUMO energy gap (10.82 eV). 1 Despite this, nature has found a number of ways to transform N 2 to bio-available molecules; for example the conversion of N 2 to NH 3 by nitrogenase. 2 Moreover, the artificial production of more than 200 million tonnes/annum of ammonia from N 2 and H 2 is achieved using heterogeneous d-block metal catalysts in the Haber–Bosch process.…”

“…boron) compound, was not reported until 2018, by Braunschweig and co-workers. 1,6 Similarly, and although elemental lithium is well known to react with N 2 to give Li 3 N under ambient conditions, 7 the only solely s-block metal complex to effect coordination and activation of N 2 in solution was described by Harder and co-workers in 2021. 8,9 This was achieved by reducing a solution of an extremely bulky β-diketiminato calcium iodide complex, under an N 2 atmosphere, with 5% w/w K/KI, 10 yielding complexes 1 , after treatment with cyclic ether donors (Fig.…”

The development of catalysts for electrochemical nitrogen reduction toward ammonia: theoretical and experimental advances

“…85,86 As Lewis acids, main-group elements with empty p-orbitals can accept lone-pair electrons from N 2 via a Lewis acid-base interaction; at the same time, a p-electron backdonation process involving partially occupied p-orbitals can activate N 2 . 87 As a representative main-group metal, Sn has emerged as a potential electrocatalyst for the eNRR due to its advantages of natural abundance, low cost, and environmental friendliness. 88,89 In addition, Sn has relatively low HER activity, which helps to suppress the competing HER, improving the NH 3 yield and FE of the eNRR.…”

Single-Atom Low-Valent Alkaline-Earth-Metal Catalysts for Electrochemical Nitrogen Reduction with an Acceptance–Backdonation Mechanism

“…23−26 However, the NRR performance and underlying reduction mechanism of low-valent s-block metals are elusive. 25,27 Therefore, it is of great interest to design low-valent AEMbased SACs for NRR and clarify the activation and reduction mechanism toward N 2 molecules.…”

“…Recently, s-block AEM-based SACs, such as Mg and Ca, have been synthesized in graphene framework, graphene nanoribbons, doped carbon substrate, and so on, which show excellent catalytic activity for oxygen reduction, − while their application in the NRR has been rarely reported. Moreover, the investigation of low-valent AEMs has attracted extensive attention in recent years because of their special structure, high reactivity, and strong reducing ability toward reactants, such as Na + and inert N 2 . − However, the NRR performance and underlying reduction mechanism of low-valent s-block metals are elusive. , Therefore, it is of great interest to design low-valent AEM-based SACs for NRR and clarify the activation and reduction mechanism toward N 2 molecules.…”