The reliability of DFT methods to predict electronic structures and minimum energy crossing point for [Fe<sup>IV</sup>O](OH)<sub>2</sub> models: A comparison study with MCQDPT method

Liu, Kun; Li, Yu‐Xue; Su, Jia-Ling; Wang, Bin

doi:10.1002/jcc.23535

Cited by 6 publications

(2 citation statements)

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“…For a two-state reaction, the minimum energy crossing point (MECP) between potential energy surface (PES) of different spin states must be located to calculate the reaction barrier. In the present work, the MECPs were located with the code developed by Harvey and co-workers . In organometallic chemistry, B3LYP is widely used in two-state mechanistic studies .…”

Section: Models and Methodsmentioning

confidence: 99%

General Reaction Mode of Hypervalent Iodine Trifluoromethylation Reagent: A Density Functional Theory Study

Lin

Liu

et al. 2015

ACS Catal.

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The mechanisms of trifluoromethylation with hypervalent iodine trifluoromethylation reagent (Togni's reagent 1) have been comprehensively studied by density functional theory (DFT) calculations. The results show that there are two general reaction modes for reagent 1: (I) Mode-A, acting as a CF 3• free radical source. When one-electron reductants are available in the reaction system, such as Cu I , Fe II , TEMPONa, or electron-rich lithium enolate, 1 will be reduced via single-electron transfer (SET) and give out CF 3• free radical concertedly. In the Cu I -catalyzed trifluoromethylation of terminal olefins, Cu I promotes the homo-cleavage of the F 3 C−I bond in 1 via SET to produce Cu II species and CF 3• free radical. Then the CF 3• free radical attacks the olefin, leading to trifluoromethyl alkyl radical intermediate. Subsequently, the Cu II species act as a one-electron oxidant oxidizing the alkyl radical to carbocation intermediate, and the following deprotonation leads to the final product. Other mechanisms, such as formation of F 3 C−Cu III species via oxidative addition, formation of allylic radical intermediate, were considered and excluded. (II) Mode-B, acting as a CF 3 + cation source. 1 can be activated by a Lewis acid such as Zn II and becomes more inclined to undergo an S N 2 type nucleophilic attack at the CF 3 group by nucleophiles (pentanol in this work). For substrates studied in this paper, such as the lithium enolate, pentanol, and sodium 2,4,6-trimethylphenolate, the competition between their reducibility and nucleophilicity determines the reaction mode of regent 1.

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Section: Models and Methodsmentioning

confidence: 99%

General Reaction Mode of Hypervalent Iodine Trifluoromethylation Reagent: A Density Functional Theory Study

Lin

Liu

et al. 2015

ACS Catal.

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“…This program can be obtained from the authors upon request. The early version of this program has been used successfully to search the MECP. − …”

Section: Methodsmentioning

confidence: 99%

Toward Understanding the Decomposition of Carbonyl Diazide (N₃)₂C═O and Formation of Diazirinone cycl-N₂CO: Experiment and Computations

Zeng

et al. 2015

J. Phys. Chem. A

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Carbonyl diazide, (N3)2CO (I), is a highly explosive compound. The isolation of the substance in a neat form was found to provide unique access to two other high-energy molecules, namely, N3-NCO (III) and cycl-N2CO (IV), among the decomposition products of (I). To understand the underlying reaction mechanism, the decomposition reactions including the thermal conversion of two conformers of (I) were revisited, and the potential energy surface (PES) was computationally explored by using the methods of B3LYP/6-311+G(3df) and CBS-QB3. The most stable syn-syn structure (I) readily converts into the syn-anti conformer (ΔHexptl = 1.1 ± 0.5 kcal mol(-1)), which undergoes decomposition in two competing pathways: a concerted path to N3-NCO (III) or a stepwise route to (III) via the nitrene intermediate N3C(O)N (1)(II). The calculated activation barriers (Ea) are almost the same (∼33 kcal mol(-1), B3LYP/6-311+G(3df)). Further decomposition of (III) occurs through a concerted fragmentation into 2 N2 + CO with a moderate Ea of 22 kcal mol(-1), and this process is compared to the isoelectronic species N3-N3 → 3 N2 (Ea = 17 kcal mol(-1)) and OCN-NCO → N2 + 2 CO (61 kcal mol(-1)). No low-energy pathway leading to (IV) was found on the singlet PES. However, the intervention of triplet ground-state (3)(II) from the initially generated (1)(II) through an intersystem crossing (ISC) offers a likely approach to (IV); that is, (3)(II) can decompose in a concerted process (Ea = 30 kcal mol(-1)) by eliminating one N2 to yield the disfavored OCNN (3)(VI). A careful intrinsic reaction coordinate analysis and a combined energy scan of the N-C-N angle reveals a bifurcation point on this triplet PES, which allows a spin crossover to the singlet PES along the reaction coordinate and eventually leads to the formation of the metastable diazirinone (IV).

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Theoretical reflections on the structural polymorphism of the oxygen-evolving complex in the S2 state and the correlations to substrate water exchange and water oxidation mechanism in photosynthesis

Guo

et al. 2017

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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The structural polymorphism of the oxygen-evolving complex is of great significance to photosynthetic water oxidation. Employing density functional theory calculations, we have made further advisement on the interconversion mechanism of O5 transfer in the S state, mainly focusing on the potentiality of multi-state reactivity and spin transitions. Then, O5 protonation is proven impossible in S for irreversibility of the interconversion, which serves as an auxiliary judgment for the protonation state of O5 in S. Besides, the structural polymorphism could also be archived by alternative mechanisms involving Mn3 ligand exchange, one of which with Mn3(III) makes sense to substrate water exchange in S, although being irresponsible for the derivations of the observed EPR signals. During the water exchange, high-spin states would prevail to facilitate electron transfer between the ferromagnetically coupled Mn centers. In addition, water exchange in S could account for the closed-cubane structure as the initial form entering S at cryogenic temperatures. With regard to water oxidation, the structural flexibility and variability in both S and S guarantee smooth W2-O5 coupling in S, according to the substrate assignments from water exchange kinetics. Within this theoretical framework, the new XFEL findings on S-S can be readily rationalized. Finally, an alternative mechanistic scenario for OO bond formation with ·OH radical near O4 is presented, followed by water binding to the pivot Mn4(III) from O4 side during S-S. This may diversify the substrate sources combined with the Ca channel in water delivery for the forthcoming S-cycle.

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The reliability of DFT methods to predict electronic structures and minimum energy crossing point for [Fe^IVO](OH)₂ models: A comparison study with MCQDPT method

Cited by 6 publications

References 49 publications

General Reaction Mode of Hypervalent Iodine Trifluoromethylation Reagent: A Density Functional Theory Study

General Reaction Mode of Hypervalent Iodine Trifluoromethylation Reagent: A Density Functional Theory Study

Toward Understanding the Decomposition of Carbonyl Diazide (N₃)₂C═O and Formation of Diazirinone cycl-N₂CO: Experiment and Computations

Theoretical reflections on the structural polymorphism of the oxygen-evolving complex in the S2 state and the correlations to substrate water exchange and water oxidation mechanism in photosynthesis

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The reliability of DFT methods to predict electronic structures and minimum energy crossing point for [FeIVO](OH)2 models: A comparison study with MCQDPT method

Cited by 6 publications

References 49 publications

General Reaction Mode of Hypervalent Iodine Trifluoromethylation Reagent: A Density Functional Theory Study

General Reaction Mode of Hypervalent Iodine Trifluoromethylation Reagent: A Density Functional Theory Study

Toward Understanding the Decomposition of Carbonyl Diazide (N3)2C═O and Formation of Diazirinone cycl-N2CO: Experiment and Computations

Theoretical reflections on the structural polymorphism of the oxygen-evolving complex in the S2 state and the correlations to substrate water exchange and water oxidation mechanism in photosynthesis

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Product

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About

The reliability of DFT methods to predict electronic structures and minimum energy crossing point for [Fe^IVO](OH)₂ models: A comparison study with MCQDPT method

Toward Understanding the Decomposition of Carbonyl Diazide (N₃)₂C═O and Formation of Diazirinone cycl-N₂CO: Experiment and Computations