ic2c00174_si_001.pdf (7.98 MB)
Gold-Aluminyl and Gold-Diarylboryl Complexes: Bonding and Reactivity with Carbon Dioxide
journal contribution
posted on 2022-05-05, 22:06 authored by Diego Sorbelli, Elisa Rossi, Remco W.A. Havenith, Johannes E.M.N. Klein, Leonardo Belpassi, Paola BelanzoniThe unconventional
carbon dioxide insertion reaction of a gold-aluminyl
[tBu3PAuAl(NON)] complex has been recently shown
to be related to the electron-sharing character of the Au–Al
bond that acts as a nucleophile and stabilizes the insertion product
through a radical-like behavior. Since a gold-diarylboryl [IPrAuB(o-tol)2] complex with similar reactivity features
has been recently reported, in this work we computationally investigate
the reaction of carbon dioxide with [LAuX] (L = phosphine, N-heterocyclic
carbene (NHC); X = Al(NON), B(o-tol)2)
complexes to get insights into the Al/B anionic and gold ancillary
ligand effects on the Au–Al/B bond nature, electronic structure,
and reactivity of these compounds. We demonstrate that the Au–Al
and Au–B bonds possess a similar electron-sharing nature, with
diarylboryl complexes displaying a slightly more polarized bond as
Au(δ+)–B(δ–). This
feature reduces the radical-like reactivity toward CO2,
and the Al/B anionic ligand effect is found to favor aluminyls over
boryls, despite the greater oxophilicity of B. Remarkably, the ancillary
ligand of gold has a negligible electronic trans effect on the Au–X
bond and only a minor impact on the formation of the insertion product,
which is slightly more stable with carbene ligands. Surprisingly,
we find that the modification of the steric hindrance at the carbene
site may exert a sizable control over the reaction, with more sterically
hindered ligands thermodynamically disfavoring the formation of the
CO2 insertion product.
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nhc ); xau ( δau – al3 sub2 subsimilar reactivity featuresdiarylboryl complexes displayingaluminyl [< supb bond nature supsharing naturepolarized bonddiarylboryl complexessteric hindrancesizable controlsimilar electronsharing characterrecently shownrecently reportedminor impactlike behavioripraub (<insertion productheterocyclic carbenegreater oxophilicityget insightsfeature reducesfavor aluminylselectronic structurecomputationally investigatecarbon dioxidecarbene ligandsb anionicancillary ligand