Facing the Challenges of Borderline Oxidation State Assignments Using State-of-the-Art Computational Methods

Gimferrer, Martí; Mynsbrugge, Jeroen Van der; Bell, Alexis T.; Salvador, P.; Head‐Gordon, Martin

doi:10.1021/acs.inorgchem.0c02405

“…A threshold of 60% in the atomic population was used to decide whether the electron pair is assigned to the TM or not. Recently, some of us 35 described an extension to the method, loosening the weight of the aforementioned threshold in the OS determination, to allow the possibility of covalent assignment (split between two atoms/fragments), and introducing a confidence measure for the assignment (either ionic or covalent) of each electron pair.…”

Section: Introductionmentioning

confidence: 99%

“…In that work 35 we observed that for some of the most challenging systems such as TMcarbenes, the LOBA method struggled to reach the accepted OS. Careful inspection of the localized orbitals indicated that the first step of the procedure, namely the orbital localization, was not always producing orbitals one could easily relate to a Lewis structure.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Oxidation State Localized Orbitals: A Method for Assigning Oxidation States Using Optimally Fragment-Localized Orbitals and a Fragment Orbital Localization Index

Gimferrer

¹

,

Salvador

²

,

Head‐Gordon

³

2021

J. Chem. Theory Comput.

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Oxidation states represent the ionic distribution of charge in a molecule, and are significant in tracking redox reactions and understanding chemical bonding. While e↵ective algorithms already exist based on formal Lewis structures, as well as using localized orbitals, they exhibit di↵erences in challenging cases where e↵ects such as redox non-innocence are at play. Given a density functional theory (DFT) calculation with chosen total charge and spin multiplicity, this work reports a new approach to obtaining fragment-localized orbitals that is termed oxidation state localized orbitals 1 (OSLO), together with an algorithm for assigning the oxidation state using the OSLOs and an associated fragment orbital localization index (FOLI). Evaluating the FOLI requires fragment populations, and for this purpose a new version of the intrinsic atomic orbital (IAO) scheme is introduced in which the IAOs are evaluated using a reference minimal basis formed from on-the-fly superposition of atomic density (IAO-AutoSAD) calculations in the target basis set, and at the target level of theory. The OSLO algorithm is applied to a range of challenging cases including high valent metal oxide complexes, redox non-innocent NO and dithiolate transition metal complexes, a range of carbene-containing TM complexes, and other examples including the potentially inverted ligand field in [Cu(CF 3 ) 4 ] . Across this range of cases, OSLO produces generally satisfactory results. Furthermore, in borderline cases, the OSLOs and associated FOLI values provide direct evidence of the emergence of covalent interactions between fragments that nicely complements existing approaches.

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“…The EOS analysis has been recently used to assign oxidation states in a number of nontrivial molecules. 95,[117][118][119][120][121] In this work, we have employed APOST3D (dev. ver.…”

Section: Methodsmentioning

confidence: 99%

How Many Electrons Holds a Molecular Electride?

Sitkiewicz¹,

Ramos‐Cordoba²,

Luis³

et al. 2021

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0

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<div> <div> <div> <p>Electrides are very peculiar ionic compounds where electrons occupy the anionic positions. In a crystal lattice, these isolated electrons often group forming channels or surfaces, furnishing electrides with a plethora of traits with promising technological applications. Despite their huge potential, thus far, only a few stable electrides have been produced because of the intricate synthesis they entail. Due to the difficulty in assessing the presence of isolated electrons, the characterization of electrides also poses some serious challenges. In fact, their properties are expected to depend on the arrangement of these electrons in the molecule. Among the criteria that we can use to characterize electrides, the presence of a non-nuclear attractor (NNA) of the electron density is both the rarest and the most salient feature. Therefore, a correct description of the NNA is crucial to determine the properties of electrides. In this paper, we analyze the NNA and the surrounding region of nine molecular electrides with the goal of determining the number of isolated electrons that are held in the electride. We have seen that the correct description of a molecular electride hinges on the electronic structure method employed for the analyses. In particular, one should employ a basis set with sufficient flexibility to describe the region close to the NNA and a density functional approximation that does not suffer from large delocalization errors. Finally, we have classified these nine molecular electrides according to the most likely number of electrons that we can find in the NNA. We believe this classification highlights the strength of the electride character and will prove useful in the design of new electrides.</p> </div> </div> </div>

show abstract

“…The EOS analysis has been recently used to assign oxidation states in a number of nontrivial molecules. 95,[117][118][119][120][121] In this work, we have employed APOST3D (dev. ver.…”

Section: Methodsmentioning

confidence: 99%

How Many Electrons Holds a Molecular Electride?

Sitkiewicz¹,

Ramos‐Cordoba²,

Jm³

et al. 2021

Preprint

0

View full text Add to dashboard Cite

<div> <div> <div> <p>Electrides are very peculiar ionic compounds where electrons occupy the anionic positions. In a crystal lattice, these isolated electrons often group forming channels or surfaces, furnishing electrides with a plethora of traits with promising technological applications. Despite their huge potential, thus far, only a few stable electrides have been produced because of the intricate synthesis they entail. Due to the difficulty in assessing the presence of isolated electrons, the characterization of electrides also poses some serious challenges. In fact, their properties are expected to depend on the arrangement of these electrons in the molecule. Among the criteria that we can use to characterize electrides, the presence of a non-nuclear attractor (NNA) of the electron density is both the rarest and the most salient feature. Therefore, a correct description of the NNA is crucial to determine the properties of electrides. In this paper, we analyze the NNA and the surrounding region of nine molecular electrides with the goal of determining the number of isolated electrons that are held in the electride. We have seen that the correct description of a molecular electride hinges on the electronic structure method employed for the analyses. In particular, one should employ a basis set with sufficient flexibility to describe the region close to the NNA and a density functional approximation that does not suffer from large delocalization errors. Finally, we have classified these nine molecular electrides according to the most likely number of electrons that we can find in the NNA. We believe this classification highlights the strength of the electride character and will prove useful in the design of new electrides.</p> </div> </div> </div>

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Facing the Challenges of Borderline Oxidation State Assignments Using State-of-the-Art Computational Methods

Cited by 34 publications

References 42 publications

Oxidation State Localized Orbitals: A Method for Assigning Oxidation States Using Optimally Fragment-Localized Orbitals and a Fragment Orbital Localization Index

Oxidation State Localized Orbitals: A Method for Assigning Oxidation States Using Optimally Fragment-Localized Orbitals and a Fragment Orbital Localization Index

How Many Electrons Holds a Molecular Electride?

How Many Electrons Holds a Molecular Electride?

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