Structural Insights into Active Catalyst Structures and Oxidative Addition to (Biaryl)phosphine−Palladium Complexes via Density Functional Theory and Experimental Studies

2007 ◽  
Vol 26 (9) ◽  
pp. 2183-2192 ◽  
Author(s):  
Timothy E. Barder ◽  
Mark R. Biscoe ◽  
Stephen L. Buchwald
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Active Catalyst ◽  
Experimental Studies ◽  
Oxidative Addition ◽  
Palladium Complexes ◽  
Functional Theory ◽  
Structural Insights

scholarly journals Influence of Varying Functionalization on the Peroxidase Activity of Nickel(II)–Pyridine Macrocycle Catalysts: Mechanistic Insights from Density Functional Theory

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 52
Author(s):  
Jerwin Jay E. Taping ◽  
Junie B. Billones ◽  
Voltaire G. Organo
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Density Functional ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Stoichiometric Ratio ◽  
Functional Theory ◽  
Pendant Arm ◽  
Spin Singlet

Nickel(II) complexes of mono-functionalized pyridine-tetraazamacrocycles (PyMACs) are a new class of catalysts that possess promising activity similar to biological peroxidases. Experimental studies with ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), substrate) and H2O2 (oxidant) proposed that hydrogen-bonding and proton-transfer reactions facilitated by their pendant arm were responsible for their catalytic activity. In this work, density functional theory calculations were performed to unravel the influence of pendant arm functionalization on the catalytic performance of Ni(II)–PyMACs. Generated frontier orbitals suggested that Ni(II)–PyMACs activate H2O2 by satisfying two requirements: (1) the deprotonation of H2O2 to form the highly nucleophilic HOO−, and (2) the generation of low-spin, singlet state Ni(II)–PyMACs to allow the binding of HOO−. COSMO solvation-based energies revealed that the O–O Ni(II)–hydroperoxo bond, regardless of pendant arm type, ruptures favorably via heterolysis to produce high-spin (S = 1) [(L)Ni3+–O·]2+ and HO−. Aqueous solvation was found crucial in the stabilization of charged species, thereby favoring the heterolytic process over homolytic. The redox reaction of [(L)Ni3+–O·]2+ with ABTS obeyed a 1:2 stoichiometric ratio, followed by proton transfer to produce the final intermediate. The regeneration of Ni(II)–PyMACs at the final step involved the liberation of HO−, which was highly favorable when protons were readily available or when the pKa of the pendant arm was low.

A Density Functional Theory Study of Coniferyl Alcohol Intermonomeric Cross Linkages in Lignin - Three-Dimensional Structures, Stabilities and the Thermodynamic Control Hypothesis

Holzforschung ◽  
2003 ◽  
Vol 57 (2) ◽  
pp. 150-164 ◽  
Author(s):  
B. Durbeej ◽  
L.A. Eriksson
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Structural Features ◽  
Density Functional Theory Study ◽  
Thermodynamic Control ◽  
Functional Theory ◽  
Quantitative Correlation ◽  
Control Hypothesis

Summary Density functional theory methods are utilized to investigate structural features and stabilities of the most common lignin dimerization products. It is found that intra-molecular hydrogen bonding acts as a stabilizing force in the lowest-energy conformer(s) of several different dimeric lignin structures. Furthermore, the calculations show that the hypothesis of thermodynamic control of monolignol dimerization accounts for some of the results obtained in experimental studies aimed at determining the ratios of intermonomeric linkages. A quantitative correlation between experimentally observed ratios and calculated relative energies cannot, however, be pointed out.

Differences in chemical properties and reactivity patterns of mono- and dioxomanganese(V) porphyrins as revealed by density functional theory

2013 ◽  
Vol 17 (10) ◽  
pp. 954-963 ◽  
Author(s):  
Sam P. de Visser
Keyword(s):  
Density Functional Theory ◽  
Ligand Exchange ◽  
Density Functional ◽  
Experimental Studies ◽  
Chemical Properties ◽  
Hydrogen Atom Abstraction ◽  
Functional Theory ◽  
Orbital Interactions ◽  
Catalytic Potential ◽  
Unique Mechanism

Recent experimental studies of Liu and Groves (J. Am. Chem. Soc. 2010; 132: 12847) on dioxomanganese(V) porphyrin complexes implicated substrate halogenation in good yield. Currently, little is known of this unique mechanism, therefore to gain understanding on the halogenation mechanism and the chemical features of this oxidant we decided to do a computational (density functional theory) study. We show that the dioxomanganese(V) complex has considerably different molecular (valence) orbitals as compared to monooxomanganese(V) porphyrin due to mixing of the metal 3d orbitals with 2p orbitals on both oxygen atoms. This results in a set of three pairs of orbitals of which the bonding and nonbonding pairs are doubly occupied and the antibonding orbitals are vacant. As a consequence, the bonding character along the Mn–O bond is less in dioxomanganese(V) as compared to monooxomanganese(V) complexes and therefore this bond can formally be described as a double bond rather than a triple bond. The differences in orbital interactions and orbital energies also affect the intrinsic chemical properties of the oxidants, such as the electron affinity and pKa values, which result in enhanced catalytic potential for dioxomanganese(V) porphyrin. Our calculations predict a halogenation mechanism in line with that proposed by experiment with an initial hydrogen atom abstraction followed by ligand exchange and halogen transfer.

The Influence of Ni(II) and Co(II) Adsorptions in the Anomalous Behavior of Co-Ni Alloys: Density Functional Theory and Experimental Studies

2017 ◽  
Vol 2 (5) ◽  
pp. 1826-1834 ◽  
Author(s):  
Jorge Vazquez-Arenas ◽  
Guadalupe Ramos-Sanchez ◽  
Rene H. Lara ◽  
Issis Romero-Ibarra ◽  
M. Eng. Francisco Almazan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Experimental Studies ◽  
Anomalous Behavior ◽  
Functional Theory ◽  
Ni Alloys

Octahedral perfluoroalkyl complexes of Ir(III) formed by oxidative addition of perfluoroalkyl iodides to Ir(acac)(CO)2

2009 ◽  
Vol 87 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Hui Huang ◽  
N Raluca Hurubeanu ◽  
Cheryl J Bourgeois ◽  
Sue-Mei Cheah ◽  
Jian Yuan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Quantitative Estimation ◽  
Oxidative Addition ◽  
Thermodynamic Control ◽  
Functional Theory ◽  
X Ray ◽  
Trans Addition ◽  
Very High

Oxidative addition of primary, secondary, or benzylic perfluoroalkyl iodides (RF–I) to the phosphine free Ir(I) precursor Ir(acac)(CO)2 1 (acac = 2,4-pentanedionato) proceeds smoothly to afford octahedral Ir(III) products Ir(acac)(I)(RF)(CO)2, A combination of X-ray crystallographic studies and solution spectroscopy shows that these products are the result of overall trans-addition of the C–I bond to iridium, probably a result of thermodynamic control; evidence for a kinetic product resulting from net cis-addition is obtained in one case. Treatment of the Ir(III) compounds with AgOTf (Tf = CF3SO3) illustrates that the iodo ligand is replaced by triflate with retention of stereochemistry at Ir. The resulting triflate complexes are inert to displacement by H2O or H2. The Ir(III) products exhibit very high CO stretching frequencies in the IR, indicating that the CO ligands may be non-classical. A quantitative estimation of the degree of backbonding to the CO ligands in these compounds, and a comparison of the π-acceptor properties of CO and fluoroalkyl ligands, is made using an approach based on Density Functional Theory (DFT) and Natural Bond Orbital analyses.Key words: iridium, fluoroalkyl, oxidation, carbonyl, DFT.

scholarly journals Application of Density Functional Theory in Coordination Chemistry: A Case Study of Group 13 Monohalide as a Ligand

2021 ◽  
Author(s):  
Thayalaraj Christopher Jeyakumar ◽  
Francisxavier Paularokiadoss
Keyword(s):  
Density Functional Theory ◽  
Coordination Chemistry ◽  
Density Functional ◽  
Experimental Studies ◽  
Theoretical Studies ◽  
Dft Methods ◽  
Functional Theory ◽  
Group 13 ◽  
Metal Bonding

The chemistry of Group 13 Monohalide is of great interest due to its isoelectronic relationship with carbon monoxide and dinitrogen. In recent years, theoretical and experimental studies have been evolved on the group-13 atom-based diatomic molecules as a ligand. The synthetic, characterisation and reactivity of various metal complexes have been well discussed in recent reviews. The nature of the metal bonding of these ligands of various types has been explained in addition by the variety of theoretical studies (using DFT methods) such as FMO and EDA. This chapter has a comprehensive experimental and theoretical study of group 13 monohalides as a ligand in coordination chemistry.

scholarly journals Skin Sensitization Calculation, Topical anti-inflammatory effect and DFT Study of New Indole-Hydrazone

2019 ◽  
Vol 9 (6) ◽  
pp. 43-46
Author(s):  
Kamel Mokhnache ◽  
Ahlem Karbab ◽  
EL-Khamsa Soltani ◽  
Soraya Madoui ◽  
Hanane Khither ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Experimental Studies ◽  
Skin Sensitization ◽  
Mice Model ◽  
Functional Theory ◽  
Anti Inflammatory ◽  
Inflammatory Effect

A new indol-hydrazone (IH); N'-[(E)-(5-bromo-1H- indol-3-yl) methylidene] pyridine-4-carbohydrazide was selected for theoretical and experimental studies. Molecular structure proprieties were investigated using density functional theory (DFT) via B3LYP/6-31G (d,p), skin sensitization prediction was carried out using Pred Skin software program. The obtained results demonstrate the reactivity of IH with Energy gap (Δ) of 0.0579 a.u, low sensitizer effect towards human skin with probability of 60 %, and an excellent topical anti-inflammatory effect against xylen-induced ear odema in mice model with inhibition percentages of 81.48%. Keyword: Hydrazone, skin sensitization, Topical, Anti-inflammatory.

scholarly journals Theoretical investigation on the effect of the ligand on bis-silylation of C(sp)–C(sp) by Ni complexes

RSC Advances ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 1005-1010
Author(s):  
Li Hui ◽  
He Yuhan ◽  
Wang Jiaqi
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Transition Metal ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Active Catalyst ◽  
Organic Ligand ◽  
Organic Complex ◽  
Functional Theory ◽  
Rate Determining Step

Density functional theory (DFT) is used to study the bis-silylation of alkynes catalyzed by a transition metal nickel–organic complex; the active catalyst, the organic ligand, the reaction mechanism, and rate-determining step are discussed in this paper.

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