# Binuclear Acetoniminato Derivatives of Iron and Chromium Carbonyls: A Theoretical Study

## TL;DR

This study uses theoretical methods to explore the structures and stability of iron and chromium compounds with acetoniminato ligands.

## Contribution

The paper identifies energetically preferred structures for binuclear iron and chromium carbonyl derivatives with acetoniminato ligands.

## Key findings

- The (Me2C=N)2Fe2(CO)6 structure is energetically preferred for iron systems with bridging ligands.
- Chromium systems prefer a structure with a 2,3-diazabutadiene ligand bonded to chromium moieties.
- Tetracarbonyl iron systems favor a structure where one ligand bonds via its C=N double bond.

## Abstract

The structures and energetics of binuclear acetoniminato
metal
carbonyl derivatives of the types (Me2CN)2Fe2(CO)
n
and (Me2CN)2Cr2(CO)
n
have been investigated by density functional theory. The (Me2CN)2Fe2(CO)6 structure,
with bridging Me2CN ligands using only their nitrogen
atoms to bridge an FeFe bond related to experimentally known
species, as well as a related (Me2CN)2Cr2(CO)8 structure, appear to be energetically
preferred. Among carbonyl-richer systems, the iron system energetically
prefers a {Me2CNC­(O)}2Fe2(CO)6 structure with bridging Me2CNC­(O)
ligands, whereas the chromium system energetically prefers a structure
with a 2,3-diazabutadiene ligand having each nitrogen atom bonded
to a Cr­(CO)5 moiety. Preferred structures for systems with
fewer CO groups include the tetracarbonyl (Me2CN)2Fe2(CO)4 in which one of the bridging
Me2CN uses its CN double bond to bond to
an iron atom, as well as (Me2CN)2Cr2(CO)
n
(n = 7,
6) structures with chromium–chromium multiple bonds bridged
by Me2CN groups.