Revisiting the Bonding Model for Gold(I) Species: The Importance of Pauli Repulsion Revealed in a Gold(I)‐Cyclobutadiene Complex

Wong, Zeng Rong; Schramm, Tim K.; Loipersberger, Matthias; Head‐Gordon, Martin; Toste, F. Dean

doi:10.1002/ange.202202019

Cited by 1 publication

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“…The larger Pauli repulsion contribution at TSI syn Au may be rationalized on the basis of the more spatially extended 5d Au compared to the 3d Cu orbitals, as recently highlighted by Toste, Head-Gordon and co-workers. 51 On the other hand, the increased orbital energy stabilization coming from the increased ΔE oi (and in particular ΔE oi 1 ) at TSI syn Cu with respect to TSI syn Au can be explained by analyzing the HOMO (i.e., the main filled molecular orbital of the complexes involved in the Δρ 1 ' component) of the metal−aluminyl complexes at their corresponding transition state structure, as shown in Figure 7.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Mechanistic Study of Alkyne Insertion into Cu–Al and Au–Al Bonds: A Paradigm Shift for Coinage Metal Chemistry

Sorbelli

Belpassi²,

Belanzoni

2022

Inorg. Chem.

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In this work, the mechanism of the insertion reaction of 3-hexyne into Cu−Al and Au−Al bonds in M−aluminyl (M = Cu, Au) complexes is computationally elucidated. The mechanism is found to be radical-like, with the Cu−Al and Au−Al bonds acting as nucleophiles toward the alkyne, and predicts a less efficient reactivity for the gold−aluminyl complex. The proposed mechanism well rationalizes the kinetic (or thermodynamic) control on the formation of the syn (or anti) insertion product into the Cu−Al bond (i.e., dimetallated alkene) which has been recently reported. A comparative analysis of the electronic structure reveals that the reduced reactivity at the gold site�usually showing higher efficiency than copper as a "standard" electrophile in alkyne activation�arises from a common feature, i.e., the highly stable 6s Au orbital. The relativistic lowering of the 6s orbital, making it more suitable for accepting electron density and thus enhancing the electrophilicity of gold complexes, in the gold−aluminyl system is responsible for a less nucleophilic Au−Al bond and, consequently, a less efficient alkyne insertion. These findings demonstrate that the unconventional electronic structure and the electron-sharing nature of the M−Al bond induce a paradigm shift in the properties of coinage metal complexes. In particular, the peculiar radical-like reactivity, previously shown also with carbon dioxide, suggests that these complexes might efficiently insert/activate other small molecules, opening new and unexplored paths for their reactivity.

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Section: ■ Results and Discussionmentioning

confidence: 99%