# Divergent Organomagnesium Reactivity of Rigid, Dinucleating Naphthyridine Ligands: Backbone Changes with Big Impact

## TL;DR

This paper explores how small changes in ligand structure significantly affect the reactivity and stability of organomagnesium complexes.

## Contribution

The study reveals how ligand architecture influences steric strain and reactivity in dimagnesium complexes.

## Key findings

- Amide-based ligands reduce steric strain around the Mg2Cl2 core.
- Secondary amine ligands form stable complexes, while amide ligands trigger radical reactions.
- Ligand architecture profoundly impacts coordination chemistry and reactivity.

## Abstract

We report the synthesis and characterization of two naphthyridine-based
ligands bearing pendant secondary amine and amide donors, respectively.
We additionally report their deprotonation chemistry and reactivity
with dialkylmagnesium and Grignard reagents. The Grignard reactions
yield structurally distinct LMg2Cl2·(THF)
n
complexes, with the amide-based
complex exhibiting reduced steric strain from the ligand around the
Mg2Cl2 core. Comparison of the steric profiles
of the LMg2Cl2·(THF)
n
complexes reveals that this reduced steric strain
stems from the difference in binding modes of the ligands, which in
the amide case points the bulk of sterically demanding substituents
away from the Mg2Cl2 core. Reactivity of the
ligands with Mg­(n-Bu)2 shows divergent
outcomes: the secondary amine-based ligand forms the LMg2(n-Bu)2·(THF)2 complex cleanly, whereas the amide-based ligand produces
paramagnetic species via Mg–C homolysis, triggering radical
reactivity that results in ligand butylation and dimerization. These
findings underscore the unique steric and electronic features of dimagnesium
complexes supported by rigid, dinucleating naphthyridine ligands,
highlighting how variations in ligand architecture can profoundly
influence coordination chemistry and reactivity.