Inhibition of Alkali Metal Reduction of 1‐Adamantanol by London Dispersion Effects

Mears, Kristian L.; Stennett, Cary R.; Fettinger, James C.; Vasko, Petra; Power, Philip P.

doi:10.1002/ange.202201318

Cited by 6 publications

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References 38 publications

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“…Interestingly, our synthetic routes to the anticipated monosubstituted alkali metal 1-adamantoxide (MOAd 1 , M = Li, Na, and K) afforded the three-coordinate species [M(OAd 1 )(HOAd 1 ) 2 ] (Figure 16). 84 The significance of this result illustrates the first example of LD interactions limiting the reduction potential of alkali metals, despite excess metal being employed. Energy decomposition analysis of this complex showed that the Ad 1 fragments afford significant dispersion stabilization (and are therefore good DED ligands): approximately one-third of the calculated total bonding energies could be assigned to dispersion effects within this molecule.…”

Section: Designing Enhanced Ld Effects In Hydrocarbon Ligandsmentioning

confidence: 79%

Beyond Steric Crowding: Dispersion Energy Donor Effects in Large Hydrocarbon Ligands

Mears

Power

2022

Acc. Chem. Res.

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Conspectus Interactions between sterically crowded hydrocarbon-substituted ligands are widely considered to be repulsive because of the intrusion of the electron clouds of the ligand atoms into each other’s space, which results in Pauli repulsion. Nonetheless, there is another interaction between the ligands which is less widely publicized but is always present. This is the London dispersion (LD) interaction which can occur between atoms or molecules in which dipoles can be induced instantaneously, for example, between the H atoms from the ligand C–H groups. These LD interactions are always attractive, but their effects are not as widely recognized as those of the Pauli repulsion despite their central role in the formation of condensed matter. Their relatively poor recognition is probably due to the relative weakness (ca. 1 kcal mol–1) of individual H···H interactions owing to their especially strong distance dependence. In contrast, where there are numerous H···H interactions, a collective LD energy equaling several tens of kcal mol–1 may ensue. As a result, in some molecules the latent importance of the LD attraction energies emerges and assumes a prominence that can overshadow the Pauli effects (e.g., in the stabilization of high-oxidation-state transition-metal alkyls, inducing disproportionation reactions, or in the stabilization of otherwise unstable bonds). Despite being known for over a century, the accurate quantification of individual H···H LD effects in molecular species is a relatively recent phenomenon and at present is based mainly on modified DFT calculations. A few leading reviews summarized these earlier studies of the C–H···H–C LD interactions in organic molecules, and their effects on the structures and stabilities were described. LD effects in sterically crowded inorganic and organometallic molecules have been recognized. The author’s interest in these LD effects arose fortuitously over a decade ago during research on sterically crowded heavier main-group element carbene analogues and two-coordinate, open-shell (d1–d9) transition-metal complexes where counterintuitive steric effects were observed. More detailed explanations of these effects were provided by dispersion-corrected DFT calculations in collaboration with the groups of Tuononen and Nagase (see below). This Account describes our development of these initial results for other inorganic molecular classes. More recently, the work has led us to move to the planned inclusion of dispersion effects in ligands to stabilize new molecular types with theoretical input from the groups of Vasko and Grimme (see below). Our approach sought to use what Grimme has described as dispersion effect donor (DED) groups (i.e., spatially close-lying, densely packed substituents either as ligands (e.g., −C6H2-2,4,6-Cy3, Cy = cyclohexyl) or as parts of ligands (e.g., a Cy substituent) that produce relatively large dispersion energies to stabilize these new compounds. We predict that the future design of sterically crowding hydrocarbon ligands will include the ...

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Section: Designing Enhanced Ld Effects In Hydrocarbon Ligandsmentioning

confidence: 79%

Beyond Steric Crowding: Dispersion Energy Donor Effects in Large Hydrocarbon Ligands

Mears

Power

2022

Acc. Chem. Res.

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Towards Hexagonal Planar Nickel: A Dispersion‐Stabilised Tri‐Lithium Nickelate

et al. 2022

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Advancing the understanding of lithum nickelate complexes, here we report a family of homoleptic organonickelate complexes obtained by reacting Ni-(COD) 2 and lithium aryl-acetylides in the presence of the bidentate donor TMEDA. These compounds represent rare examples of low-valent transition-metals supported solely by organolithium ligands. Whilst the solid-state structures indicate a hexagonal planar geometry around Ni 0 with NiÀ Li bonds, bonding analysis via QTAIM, NCI, NBO and ELI methods reveals that the NiÀ Li interactions are repulsive in nature, characterising these complexes as tri-coordinated. London dispersion forces between TMEDA and the organic substituents on nickel are found to play a crucial role in the stabilisation and thus isolation of these complexes. Preliminary reactivity studies demonstrate that the homoleptic lithium nickelates undergo stoichiometric cross-coupling with PhI to give dinickel clusters containing both anionic acetylide and neutral alkyne ligands.

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London Dispersion Effects in a Distannene/Tristannane Equilibrium: Energies of their Interconversion and the Suppression of the Monomeric Stannylene Intermediate

et al. 2023

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Reaction of {LiC6H2−2,4,6‐Cyp3⋅Et2O}2 (Cyp=cyclopentyl) (1) of the new dispersion energy donor (DED) ligand, 2,4,6‐triscyclopentylphenyl with SnCl2 afforded a mixture of the distannene {Sn(C6H2−2,4,6‐Cyp3)2}2 (2), and the cyclotristannane {Sn(C6H2−2,4,6‐Cyp3)2}3 (3). 2 is favored in solution at higher temperature (345 K or above) whereas 3 is preferred near 298 K. Van't Hoff analysis revealed the 3 to 2 conversion has a ΔH=33.36 kcal mol−1 and ΔS=0.102 kcal mol−1 K−1, which gives a ΔG300 K=+2.86 kcal mol−1, showing that the conversion of 3 to 2 is an endergonic process. Computational studies show that DED stabilization in 3 is −28.5 kcal mol−1 per {Sn(C6H2−2,4,6‐Cyp3)2 unit, which exceeds the DED energy in 2 of −16.3 kcal mol−1 per unit. The data clearly show that dispersion interactions are the main arbiter of the 3 to 2 equilibrium. Both 2 and 3 possess large dispersion stabilization energies which suppress monomer dissociation (supported by EDA results).

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Inhibition of Alkali Metal Reduction of 1‐Adamantanol by London Dispersion Effects

Cited by 6 publications

References 38 publications

Beyond Steric Crowding: Dispersion Energy Donor Effects in Large Hydrocarbon Ligands

Beyond Steric Crowding: Dispersion Energy Donor Effects in Large Hydrocarbon Ligands

Towards Hexagonal Planar Nickel: A Dispersion‐Stabilised Tri‐Lithium Nickelate

London Dispersion Effects in a Distannene/Tristannane Equilibrium: Energies of their Interconversion and the Suppression of the Monomeric Stannylene Intermediate

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