Side‐On Bonded Beryllium Dinitrogen Complexes

Abstract

The preparation and spectroscopic identification of the complexes NNBe(η2‐N2) and (NN)2Be(η2‐N2) and the energetically higher lying isomers Be(NN)2 and Be(NN)3 are reported. NNBe(η2‐N2) and (NN)2Be(η2‐N2) are the first examples of covalently side‐on bonded N2 adducts of a main‐group element. The analysis of the electronic structure using modern methods of quantum chemistry suggests that NNBe(η2‐N2) and (NN)2Be(η2‐N2) should be classified as π complexes rather than metalladiazirines.

Spectroscopic Characterization of the Synergistic Mechanism of Ruthenium–Lithium Hydrides for Dinitrogen Cleavage

“…Orbital 2 involves back-donation of a π orbital from the occupied 4d orbital of Ru to the antibonding π orbitals of N 2 . Previous studies pointed out that π back-donation would weaken the strong NN bond and was crucial for its further activation . As both σ donation and π back-donation of the 1B structure can weaken the NN bond, while only π back-donation of the 1A structure weakens the NN bond, the side-on structure (1B) is reasonably supported to contain a more activated N 2 ligand than the end-on structure (1A) in accordance with the N–N bond order of 1B.…”

“…However, current industrial ammonia production via the conventional Haber–Bosch process requires harsh operating conditions (673–773 K, 100–300 bar), which actually constitutes >1% of the world’s annual energy production. The efficient activation and transformation of dinitrogen under mild conditions is one of the formidable challenges in chemistry and has been actively pursued for more than a century. − The reduction of N 2 to NH 3 is generally mediated by transition metals because they possess unoccupied and occupied d orbitals with suitable orbital energies and symmetries, which can bind to N 2 via synergistic σ donation and π back-donation. − Transition metal–nitrogen interactions play an important role in catalytic ammonia production, which can be seen as the initial step of the complex sequential chemical activation of dinitrogen.…”

C–O Bond Activation in Mononuclear Lanthanide Oxocarbonyl Complexes OLn(η2-CO) (Ln = La, Ce, Pr, and Nd)

“…An EDA-NOCV analysis with alternative reference fragments has been carried out to distinguish the above two types of bonding. According to the theory of EDA-NOCV method, the best choice of fragments to describe the bonding situations is determined by the calculations that give the smallest energy term Δ E orb , − because the least alteration of the electronic charge distribution is required to yield the electronic structure of the molecule. In addition, the EDA-NOCV analysis is expected to provide conceptual interpretations on the interaction nature for the bonding fragments.…”

Intermediates of Carbon Monoxide Oxidation on Praseodymium Monoxide Molecules: Insights from Matrix-Isolation IR Spectroscopy and Quantum-Chemical Calculations

“…Note that the answer will shape the bonding situations of the two interacting fragments. To address the above question, an EDA-NOCV analysis with alternative reference fragments is carried out because of its ability to determine the most appropriate bonding fragments by giving the minimum orbital interactions Δ E orb . − In addition, the EDA-NOCV method has been proven to provide detailed insight into the interaction nature of the bonding fragments. Table presents a numerical comparison of the EDA-NOCV calculation results for the two intermediates using neutral or ionic fragments.…”