Charge distribution in Mn(salen) complexes

Teixeira, Filipe; Mosquera, Ricardo A.; Melo, André; Freire, Cristina; Cordeiro, M. Natália D. S.

doi:10.1002/qua.24604

Cited by 14 publications

(33 citation statements)

References 48 publications

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“…However, the fact that the salen ligand assumes a slightly bent conformation [28] and the effect of axial coordination by a donor ligand may alter this outcome. A triplet (two unpaired d electrons) or a singlet (no unpaired electrons) ground state may therefore be a viable hypotheses [29][30][31]. Table 2 shows the relative gas-phase energies of the lowest-energy singlet, triplet and quintuplet states of different non-oxo Mn(III) complexes, determined using different DFT functionals and basis sets.…”

Section: Ground State Spin Multiplicity Of Mn(salen) Speciesmentioning

confidence: 99%

“…On the other hand, manganese(V) (usually found in oxo-Mn(salen) species) has a 3d 2 configuration that allows one to postulate either a triplet or a singlet ground state. Again, the electronic structure of the Mn(V) atom will be influenced by the non-planarity of the salen ligand, the presence of the oxo-ligand and also the eventual presence of an axial ligand [11,23,31]. Because oxo-Mn(salen) complexes are extremely reactive, the absence of reliable experimental data has attracted the attention of many theoretical researchers.…”

Section: Ground State Spin Multiplicity Of Mn(salen) Speciesmentioning

confidence: 99%

“…This is partly compensated by some studies that benchmark their findings across a large number of density functionals [17,31,34,133] (and eventually, other theoretical methods [23,34,35,134]). Moreover, most works accessing the performance of B3LYP acknowledge its limitations when applied to transition metal chemistry.…”

Section: Weaknessesmentioning

confidence: 99%

“…On the other hand, the great majority of works comparing between experiment and theoretical predictions use B3LYP. One possible explanation may come from the work by Teixeira et al [31], where, despite changes in the energy ordering of the different spin states of Mn(salen) complexes, the effective atomic charges provided by a natural population analysis of these complexes vary very little with respect to the level of theory used in the energy calculation. These results are further corroborated by a topological analysis of the electron density using Bader's Quantum Theory of Atoms In Molecules (QTAIM) [31].…”

Section: Weaknessesmentioning

confidence: 99%

“…One possible explanation may come from the work by Teixeira et al [31], where, despite changes in the energy ordering of the different spin states of Mn(salen) complexes, the effective atomic charges provided by a natural population analysis of these complexes vary very little with respect to the level of theory used in the energy calculation. These results are further corroborated by a topological analysis of the electron density using Bader's Quantum Theory of Atoms In Molecules (QTAIM) [31]. Since the distribution of the electron density governs a great number of physical properties, it is likely that the limitations of B3LYP may be negligible in many cases.…”

Section: Weaknessesmentioning

confidence: 99%

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Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations

Teixeira

Cordeiro

2016

Catalysts

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Abstract:The importance of epoxides as synthetic intermediates in a number of highly added-value chemicals, as well as the search for novel and more sustainable chemical processes have brought considerable attention to the catalytic activity of manganese and iron complexes towards the epoxidation of alkenes using non-toxic terminal oxidants. Particular attention has been given to Mn(salen) and Fe(porphyrin) catalysts. While the former attain remarkable enantioselectivity towards the epoxidation of cis-alkenes, the latter also serve as an important model for the behavior of cytochrome P450, thus allowing the exploration of complex biological processes. In this review, a systematic survey of the bibliographical data for the theoretical studies on Mn-and Fe-catalyzed epoxidations is presented. The most interesting patterns and trends are reported and finally analyzed using an evaluation framework similar to the SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis performed in enterprise media, with the ultimate aim to provide an overview of current trends and areas for future exploration.

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Section: Ground State Spin Multiplicity Of Mn(salen) Speciesmentioning

confidence: 99%

Section: Ground State Spin Multiplicity Of Mn(salen) Speciesmentioning

confidence: 99%

Section: Weaknessesmentioning

confidence: 99%

Section: Weaknessesmentioning

confidence: 99%

Section: Weaknessesmentioning

confidence: 99%

See 3 more Smart Citations

Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations

Teixeira

Cordeiro

2016

Catalysts

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Exploring rare chemical phenomena using fractional nuclear charges: Thecis‐effect in N₂F₂

Teixeira

Melo

Cordeiro

2018

Int J of Quantum Chemistry

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The so called cis-effect, in which the cis form of an ethylenic compound is more stable than its trans-isomer, is a good example of a rare phenomenon described only for a few isomeric pairs. In this work, a novel approach to the study of this rare effect is attempted by changing the nuclear charges of the fluoride and nitrogen in cis-and trans-N 2 F 2 . This allowed the survey of a large number of isomeric pairs composed sharing the same molecular topology, while varying the electronegativity of selected atoms. The results show an increasing stabilization of the cis-isomers when increasing the electronegativity of the fluoride atoms, in line with the accepted zeitgeist linking this effect to the electronegativity of the peripheral groups. However, a similar behavior was also found when varying the nuclear charge of the nitrogen atoms. This prompted a more in-depth look at the electronic structure of these compounds, gathering descriptors from Bader's Quantum Theory of Atoms in Molecules. A descriptive linear model was derived from these descriptors using a two-stage stepwise linear regression. Further inspection of the model linked the destabilization of the trans-isomers with a deviation from the idealized trigonal planar geometry predicted by the Valence Shell Electron Pair Repulsion model. This tendency was explained by an increase in the ionic character of the NAF bonds. Furthermore, the current model suggests that the Coulombic repulsion between the two peripheral atoms in the cis-isomers prevents such large deviations from the idealized geometry, thus, contributing to their relative stabilization. The qualitative rules governing the cis-effect in N 2 F 2 were further tested on other compounds with a similar bond topology. K E Y W O R D Scis-effect, fractional nuclear charge, QTAIM | I N T R O D U C T I O NThe development of novel two-dimensional materials has greatly expanded, from the carbon-centered development of graphene applications into an ever-expanding world where new materials using the most common elements on the periodic table are being developed. [1] Among these new materials, boron nitride is one of the most common, yielding interesting applications in electronics [2] and medicine, [3] and re-kindling the interest for nitrogen chemistry. At the same time, azo compounds such as azobenzene play an important role as a stabilizer in polymers and liquid crystal applications. [4] Difluorodiazene (dinitrogen fluoride, N 2 F 2 ) is a lesser known member of the diazene family, remarkable for the fact that cis-difluorodiazene (1, in Figure 1) is considerably more stable than its trans-isomer (2, in Figure 1). [5] This phenomenon was first reported by Craig et al. [6] in the 1970s and is shared with a number of ethylene derivatives, such as 1,2-difluoroethene (CHFCHF), and 1,2-dichloroethene. These compounds share a common feature thatwere E trans and E cis correspond to the energy of the trans-and cis-isomers, respectively. Nevertheless, this so-called cis-effect is much more prominent in the case of N 2...

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Water‐Encapsulated Ni(II) Salphen‐Type Host Complexes: Experimental and Theoretical Analysis of Potentially Bioactive Quasi‐Isostructural Polymorphs

2017

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In this study, we report the formation of two quasi-isostructural polymorphs (a and b) of a Ni(II) salphen-type Schiff base complex using solvent evaporation technique. The polymorphs are inclusion compounds with guest water molecules exhibiting similar spectroscopic and thermal characteristics. Single crystal XRD (X-ray Diffraction) analyses reveal the subtle differences in packing and supramolecular interactions which are quantified using Hirshfeld and 2D finger print analyses. Electrostatic potential analysis shows significant difference in potential distribution in the two molecules. The compositional analysis of the frontier orbitals and differences among the atomic charge distribution of the polymorphs are established using DFT (Density Functional Theory) calculations. Apart from highlighting the strength of encapsulation, DFT study substantiates the formation of inclusion compounds through single point energy calculations. Effects of inherent differences in the polymorphs on potential biological activity are probed using in silico molecular docking with B-DNA and Human Serum Albumin (HSA). The a form shows superior bioactivity while b form excels in water encapsulation.[a] Dr.

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Charge distribution in Mn(salen) complexes

Cited by 14 publications

References 48 publications

Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations

Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations

Exploring rare chemical phenomena using fractional nuclear charges: Thecis‐effect in N₂F₂

Water‐Encapsulated Ni(II) Salphen‐Type Host Complexes: Experimental and Theoretical Analysis of Potentially Bioactive Quasi‐Isostructural Polymorphs

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Charge distribution in Mn(salen) complexes

Cited by 14 publications

References 48 publications

Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations

Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations

Exploring rare chemical phenomena using fractional nuclear charges: Thecis‐effect in N2F2

Water‐Encapsulated Ni(II) Salphen‐Type Host Complexes: Experimental and Theoretical Analysis of Potentially Bioactive Quasi‐Isostructural Polymorphs

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Exploring rare chemical phenomena using fractional nuclear charges: Thecis‐effect in N₂F₂