# Computational Experiments Probing the Adaptability of the [NCCH2]− Electronic Structure to Various Bonding Environments

## TL;DR

This paper explores how different metals and environments affect the bonding structure of metalated acetonitrile, revealing unexpected electronic flexibility.

## Contribution

The study reveals the adaptability of the [NCCH2]− electronic structure to various bonding environments through DFT and natural bond orbital analyses.

## Key findings

- C-binding is energetically favored in covalent Cu(I) complexes, while lithiated species prefer N-binding.
- N-metalated species can exhibit either ketenimine-like or nitrile-like character depending on the bonding environment.
- External electric fields can induce electronic reorganization in metalated nitriles.

## Abstract

Using combined geometry optimization and electronic analyses, it is examined how metal nature (alkali and Cu(I)), solvation (THF), ligands, and aggregation modulate the N‐ versus C‐bonding balance in metalated acetonitrile. C‐binding is energetically favored in covalent Cu(I) complexes, while lithiated species prefer N‐binding. Surprisingly, N‐metalated species do not all exhibit the expected ketenimine‐like character (C=C=N, lone pair on N), but a nitrile‐like one (C
b
—C≡N, lone pair on C
b
) also emerges from the natural bond orbital analyses. Ketenimines are stabilized by polarizing or covalent M—N bonds, while nitriles are obtained with weakly coordinating cations or in anionic species. Notably, an external electric field can induce a similar electronic reorganization, thus revealing the electronic flexibility of metalated nitriles.

Metalated nitriles are organometallic chameleons in solution, existing as a structural duality of N‐ and C‐metalated species exhibiting specific reactivities. With density functional theory (DFT) calculations and natural bond orbital analyses, it is explored how the metal nature (Li, Na, K, Cs, Cu(I)) and the chemical environment (ligand, solvation) impact this continuum. A divergence between metalation site and formal charge localization is evidenced.© 2026 WILEY‐VCH GmbH