The Experts below are selected from a list of 230013 Experts worldwide ranked by ideXlab platform
Luis R. Domingo - One of the best experts on this subject based on the ideXlab platform.
-
Unravelling the strain-promoted [3+2] cycloaddition reactions of phenyl azide with cycloalkynes from the molecular electron density theory perspective
New Journal of Chemistry, 2020Co-Authors: Luis R. Domingo, Nivedita AcharjeeAbstract:The strain-promoted [3+2] cycloaddition (SP-32CA) reactions of phenyl azide with a series of five strained cycloalkynes C5–C9 have been studied within molecular electron density theory (MEDT) at the MPWB1K/6-311G(d,p) Computational Level. These zwitterionic type SP-32CA reactions take place through a one-step mechanism, with activation enthalpies in acetonitrile between −4.2 and 19.9 kcal mol−1. An excellent linear correlation between the decrease in activation enthalpies and the ring size of this series of cycloalkynes can be established. The present study shows that the highly strained cycloalkynes C5 and C6 experience a different chemical reactivity than less strained cycloalkynes C7–C9, caused by the noticeable electrophilic character of the former ones. The present MEDT study permits establishing that the loss of the cycloalkyne strain along the reaction path together with easy depopulation of the C–CC–C bonding region along these SP-32CA reactions, and not “less distortion of the 1,3-dipole in the transition state geometry”, as has been suggested, is responsible for the kinetics and thermodynamics of these SP-32CA reactions.
-
a molecular electron density theory investigation of the molecular mechanism regioselectivity stereoselectivity and chemoselectivity of cycloaddition reaction between acetonitrile n oxide and 2 5 dimethyl 2h 1 2 3 diazarsole
Theoretical Chemistry Accounts, 2020Co-Authors: Abdellah Zeroual, Mar Riosgutierrez, Mohammed Salah, Habib El Alaoui El Abdallaoui, Mohamed El Ghozlani, Mohammed El Idrissi, Anas Ouled Aitouna, Luis R. DomingoAbstract:The cycloaddition reactions (32CA) of acetonitrile N-oxide and 2,5-dimethyl-2H-[1,2,3]diazarsole 1 have been examined employing the molecular electron density theory through DFT calculations at the B3LYP/6-31G ++(d,p) Computational Level. Investigation of the relative energies related to the competitive ortho and meta reaction paths demonstrates a high chemo-, stereo- and regioselectivity for this 32CA reaction in clear conformity with the experimental results. The topological study of the electron localisation function of the certain points of the IRC associated with the construction of the As–C and C–O single bonds shows a zwitterionic-type structure. The 32CA reaction takes place via a two-stage one-step mechanism initialised with the formation of the As–C single bond.
-
a molecular electron density theory study of the synthesis of spirobipyrazolines through the domino reaction of nitrilimines with allenoates
Molecules, 2019Co-Authors: Luis R. Domingo, Fatemeh Ghodsi, Mar RiosgutierrezAbstract:The reaction of diphenyl nitrilimine (NI) with methyl 1-methyl-allenoate yielding a spirobipyrazoline has been studied within molecular electron density theory (MEDT) at the MPWB1K/6-311G(d) Computational Level in dichloromethane. This reaction is a domino process that comprises two consecutive 32CA reactions with the formation of a pyrazoline intermediate. Analysis of the relative Gibbs free energies indicates that both 32CA reactions are highly regioselective, the first one being also completely chemoselective, in agreement with the experimental outcomes. The geometries of the TSs indicate that they are associated to asynchronous bond formation processes in which the shorter distance involves the C1 carbon of diphenyl NI. Despite the zwitterionic structure of diphenyl NI, the appearance of a pseudoradical structure at the beginning of the reaction path, with a very low energy cost, suggests that the 32CA reaction between diphenyl NI, a strong nucleophile, and the allenoate, a moderate electrophile, should be mechanistically considered on the borderline between pmr-type and cb-type 32CA reactions, somewhat closer to the latter.
-
an investigation of the molecular mechanism chemoselectivity and regioselectivity of cycloaddition reaction between acetonitrile n oxide and 2 5 dimethyl 2h 1 2 3 diazaphosphole a medt study
Journal of Chemical Sciences, 2019Co-Authors: Abdellah Zeroual, Mar Riosgutierrez, Mohammed Salah, Habib El Alaoui El Abdallaoui, Luis R. DomingoAbstract:The [3+2] cycloaddition (32CA) reactions of acetonitrile N-oxide with 2,5-dimethyl-2H-[1,2,3]diazaphosphole has been studied using the Molecular Electron Density Theory (MEDT) through DFT calculations at the B3LYP/6-31G(d,p) Computational Level. Analysis of the relative free energies associated with the competitive ortho and meta reaction paths shows high chemo- and regioselectivity for this 32CA reaction in clear agreement with the experimental outcomes. The topological analysis of the electron localization function (ELF) of the selected points of the IRC associated with the formation of the P-C and C-O single bonds indicates a zwitterionic type structure. The 32CA reaction takes place through a two-stage one-step mechanism initialized with the formation of the P-C single bond. The mechanism, the chemo-, and regioselectivity of the [3+2] cycloaddition (32CA) reaction between ethylnitrile oxide and 2,5-dimethyl-2H-[1,2,3]diazaphosphole, have been theoretically studied at the DFT/ B3LYP/6-31(d,p) Computational Level. DFT calculations account for the total chemo- and regioselectivity in total conformity with the experimental results.
-
A Molecular Electron Density Theory Study of the Chemoselectivity, Regioselectivity, and Diastereofacial Selectivity in the Synthesis of an Anticancer Spiroisoxazoline derived from α-Santonin
'MDPI AG', 2019Co-Authors: Luis R. Domingo, Mar Ríos-gutiérrez, Nivedita AcharjeeAbstract:The [3 + 2] cycloaddition (32CA) reaction of an α-santonin derivative, which has an exocyclic C⁻C double bond, with p-bromophenyl nitrile oxide yielding only one spiroisoxazoline, has been studied within the molecular electron density theory (MEDT) at the MPWB1K/6-311G(d,p) Computational Level. Analysis of the conceptual density functional theory (CDFT) reactivity indices and the global electron density transfer (GEDT) account for the non-polar character of this zwitterionic-type 32CA reaction, which presents an activation enthalpy of 13.3 kcal·mol−1. This 32CA reaction takes place with total ortho regioselectivity and syn diastereofacial selectivity involving the exocyclic C⁻C double bond, which is in complete agreement with the experimental outcomes. While the C⁻C bond formation involving the β-conjugated carbon of α-santonin derivative is more favorable than the C⁻O one, which is responsible for the ortho regioselectivity, the favorable electronic interactions taking place between the oxygen of the nitrile oxide and two axial hydrogen atoms of the α-santonin derivative are responsible for the syn diastereofacial selectivity
José Elguero - One of the best experts on this subject based on the ideXlab platform.
-
rivalry between regium and hydrogen bonds established within diatomic coinage molecules and lewis acids bases
ChemPhysChem, 2020Co-Authors: Goar Sanchezsanz, Ibon Alkorta, Cristina Trujillo, José ElgueroAbstract:A theoretical study of the complexes formed by Ag 2 and Cu 2 with different molecules, XH (FH, ClH, OH 2 , SH 2 , HCN, HNC, HCCH, NH 3 and PH 3 ) that can act as hydrogen bond donors (Lewis acids) or regium bond acceptors (Lewis bases) were carried out at the CCSD(T)/CBS Computational Level. In addition, the heteronuclear diatomic coinage molecules (AuAg, AuCu, and AgCu) have also been considered. With the exception of some of the hydrogen bonded complexes with FH, the regium bonded binary complexes are more stable. The AuAg and AuCu molecules show large dipole moments that weaken the RB bonds with Au and favours those through the Ag and Cu atoms respectively.
-
Hydrogen vs. Halogen Bonds in 1-Halo-Closo-Carboranes.
Materials, 2020Co-Authors: Ibon Alkorta, José Elguero, Josep M. Oliva-enrichAbstract:A theoretical study of the hydrogen bond (HB) and halogen bond (XB) complexes between 1-halo-closo-carboranes and hydrogen cyanide (NCH) as HB and XB probe has been carried out at the MP2 Computational Level. The energy results show that the HB complexes are more stable than the XBs for the same system, with the exception of the isoenergetic iodine derivatives. The analysis of the electron density with the quantum theory of atoms in molecules (QTAIM) shows the presence of a unique intermolecular bond critical point with the typical features of weak noncovalent interactions (small values of the electron density and positive Laplacian and total energy density). The natural energy decomposition analysis (NEDA) of the complexes shows that the HB and XB complexes are dominated by the charge-transfer and polarization terms, respectively. The work has been complemented with a search in the CSD database of analogous complexes and the comparison of the results, with those of the 1-halobenzene:NCH complexes showing smaller binding energies and larger intermolecular distances as compared to the 1-halo-closo-carboranes:NCH complexes.
-
The influence of halogen bonds on tautomerism: the case of 3-mercapto-1,2-azoles (pyrazoles, isoxazoles, isothiazoles)
Structural Chemistry, 2015Co-Authors: Marta Marín-luna, Ibon Alkorta, José ElgueroAbstract:DFT calculations at the B3LYP/6-311++G(d,p) Computational Level have been carried out on three tautomeric pairs of 3-mercapto-1,2-azoles (pyrazoles, isoxazoles, and isothiazoles) to study the effect of halogen bonds (XBs) on the position of the equilibrium. As halogen bond donors, we have selected Br_2, Cl_2, BrCl, ClF and BrF and compare them with HF as a hydrogen bond donor. Several linear relationships were found between binding energies of different halogen bond donors. The main conclusion of this study is that the XB inverts the tautomeric equilibrium while an HB does not.
-
theoretical study of the mutarotation of erythrose and threose acid catalysis
Carbohydrate Research, 2013Co-Authors: Luis Miguel Azofra, Ibon Alkorta, José ElgueroAbstract:Abstract The acid catalysis of the mutarotation mechanism in the two aldotetroses, d -erythrose and d -threose, has been studied at B3LYP/6-311++G(d,p) Computational Level in gas phase and in solution employing the PCM–water model. The open-chain, the furanose and the connecting TS structures have been characterized. To study the enhancing effect of acid groups on the electrophilicity of the carbonyl carbon atom, four situations have been considered: (i) a classical Lewis acid as BH 3 ; (ii) a classical hard-Pearson acid as Na + ; (iii) classical Bronsted acids as H + and H 3 O + ; and (iv) a combined strategy using H 3 O + and one bridge-H 2 O molecule as assistant in the proton transfer process. All the acidic groups reduce the activation energy with exception of the Na + , which can act, in some cases, as inhibitor. It is greatly reduced by the presence of Bronsted acids (iii) and through the combined strategy (iv). For this last mechanism, the electronic activation energies are between 12 and 43 kJ mol −1 in vacuum and between 13 and 25 kJ mol −1 in water solution, through the use of the PCM model.
-
a theoretical study of the neutral and the double charged cation of cyclo 8 pyrrole and its interaction with inorganic anions
Central European Journal of Chemistry, 2009Co-Authors: Ibon Alkorta, Fernando Blanco, José ElgueroAbstract:A theoretical study of the complexation of cyclo[8]pyrrole dication, 2, and the corresponding system in neutral form, 3, with six anionic molecules has been carried out up to the B3LYP/6–311++G(2d,2p) Computational Level. The effect of the water solvation has been taken into account by means of the PCM method. The gas phase results correspond to the very large interaction energies expected for the interaction of molecules of opposite charge. In all the complexes, the analysis of the electron density by means of the Atoms In Molecules (AIM) methodology shows the presence of eight intermolecular interactions between the individual molecules. The results, using the water solvent model, indicate that the 2:SO42− complex is more stable than the 2:NO3−, in agreement with experimental results.
Mar Riosgutierrez - One of the best experts on this subject based on the ideXlab platform.
-
a molecular electron density theory investigation of the molecular mechanism regioselectivity stereoselectivity and chemoselectivity of cycloaddition reaction between acetonitrile n oxide and 2 5 dimethyl 2h 1 2 3 diazarsole
Theoretical Chemistry Accounts, 2020Co-Authors: Abdellah Zeroual, Mar Riosgutierrez, Mohammed Salah, Habib El Alaoui El Abdallaoui, Mohamed El Ghozlani, Mohammed El Idrissi, Anas Ouled Aitouna, Luis R. DomingoAbstract:The cycloaddition reactions (32CA) of acetonitrile N-oxide and 2,5-dimethyl-2H-[1,2,3]diazarsole 1 have been examined employing the molecular electron density theory through DFT calculations at the B3LYP/6-31G ++(d,p) Computational Level. Investigation of the relative energies related to the competitive ortho and meta reaction paths demonstrates a high chemo-, stereo- and regioselectivity for this 32CA reaction in clear conformity with the experimental results. The topological study of the electron localisation function of the certain points of the IRC associated with the construction of the As–C and C–O single bonds shows a zwitterionic-type structure. The 32CA reaction takes place via a two-stage one-step mechanism initialised with the formation of the As–C single bond.
-
a molecular electron density theory study of the synthesis of spirobipyrazolines through the domino reaction of nitrilimines with allenoates
Molecules, 2019Co-Authors: Luis R. Domingo, Fatemeh Ghodsi, Mar RiosgutierrezAbstract:The reaction of diphenyl nitrilimine (NI) with methyl 1-methyl-allenoate yielding a spirobipyrazoline has been studied within molecular electron density theory (MEDT) at the MPWB1K/6-311G(d) Computational Level in dichloromethane. This reaction is a domino process that comprises two consecutive 32CA reactions with the formation of a pyrazoline intermediate. Analysis of the relative Gibbs free energies indicates that both 32CA reactions are highly regioselective, the first one being also completely chemoselective, in agreement with the experimental outcomes. The geometries of the TSs indicate that they are associated to asynchronous bond formation processes in which the shorter distance involves the C1 carbon of diphenyl NI. Despite the zwitterionic structure of diphenyl NI, the appearance of a pseudoradical structure at the beginning of the reaction path, with a very low energy cost, suggests that the 32CA reaction between diphenyl NI, a strong nucleophile, and the allenoate, a moderate electrophile, should be mechanistically considered on the borderline between pmr-type and cb-type 32CA reactions, somewhat closer to the latter.
-
an investigation of the molecular mechanism chemoselectivity and regioselectivity of cycloaddition reaction between acetonitrile n oxide and 2 5 dimethyl 2h 1 2 3 diazaphosphole a medt study
Journal of Chemical Sciences, 2019Co-Authors: Abdellah Zeroual, Mar Riosgutierrez, Mohammed Salah, Habib El Alaoui El Abdallaoui, Luis R. DomingoAbstract:The [3+2] cycloaddition (32CA) reactions of acetonitrile N-oxide with 2,5-dimethyl-2H-[1,2,3]diazaphosphole has been studied using the Molecular Electron Density Theory (MEDT) through DFT calculations at the B3LYP/6-31G(d,p) Computational Level. Analysis of the relative free energies associated with the competitive ortho and meta reaction paths shows high chemo- and regioselectivity for this 32CA reaction in clear agreement with the experimental outcomes. The topological analysis of the electron localization function (ELF) of the selected points of the IRC associated with the formation of the P-C and C-O single bonds indicates a zwitterionic type structure. The 32CA reaction takes place through a two-stage one-step mechanism initialized with the formation of the P-C single bond. The mechanism, the chemo-, and regioselectivity of the [3+2] cycloaddition (32CA) reaction between ethylnitrile oxide and 2,5-dimethyl-2H-[1,2,3]diazaphosphole, have been theoretically studied at the DFT/ B3LYP/6-31(d,p) Computational Level. DFT calculations account for the total chemo- and regioselectivity in total conformity with the experimental results.
-
a dft study of the conversion of ptaquiloside a bracken fern carcinogen to pterosin b in neutral and acidic aqueous medium
ChemistrySelect, 2017Co-Authors: Mar Riosgutierrez, Luis R. Domingo, Miguel E AlonsoamelotAbstract:The conversion of ptaquiloside (PtQ), a bracken fern (Pteridium aquilinum) carcinogen, to pterosin B (PtB), which is involved in the underlying mechanisms of PtQ genotoxicity and carcinogenicity, has been theoretically studied in aqueous neutral (AN) and acid (AA) media, using DFT methods at the PCM(water)-B3LYP/6-31G(d)//B3LYP/6-31G(d) Computational Level. The β-elimination of glucose in AN and four reactive channels (A-D) defined by as many protonation sites in PtQ were calculated. Activation enthalpy decreases (from 42.0 to 12.6 kcal mol−1) in AA relative to AN suggesting protic catalysis. The most favoured channel A started with protonation of the tertiary O15 hydroxyl of PtQ and SN1 water release with strong stabilisation by the spirocyclopropane ring. Natural population analysis and electron localisation function analysis showed significant electron depopulation of vicinal C−C bonds and the remarkable leaving character of the quaternary carbon, which enhanced the nucleophilic attack of water on the distal methylenes while the glucose fragment was retained. This intermediate was unstable, degrading rapidly to a stable PtB-glucose-water-H+ molecular complex whose calculated electronic spectrum (λmax=271.5 nm) matched the value of an intermediate reported earlier with a different structure. PtQ-dienone, long assumed as the carcinogenic form of PtQ, is not formed in AA but only and unfavourably so in protonated form assisted by one molecule of water.
-
understanding the domino reaction between 1 diazopropan 2 one and 1 1 dinitroethylene a molecular electron density theory study of the 3 2 cycloaddition reactions of diazoalkanes with electron deficient ethylenes
RSC Advances, 2017Co-Authors: Luis R. Domingo, Mar Riosgutierrez, Saeedreza EmamianAbstract:The reaction between 1-diazopropan-2-one and 1,1-dinitroethylene has been studied using the Molecular Electron Density Theory (MEDT) at the B3LYP/6-31G(d,p) Computational Level. This reaction comprises two domino processes initialised by a common [3 + 2] cycloaddition (32CA) reaction yielding a 1-pyrazoline, which participates in two competitive reaction channels. Along channel I, 1-pyrazoline firstly tautomerises to a 2-pyrazoline, which by a proton abstraction and spontaneous loss of nitrite anion yields the final pyrazole, while along channel II, the thermal extrusion of the nitrogen molecule in 1-pyrazoline gives a very reactive diradical intermediate which quickly yields the final gem-dinitrocyclopropane. Analysis of the conceptual DFT reactivity indices permits an explanation of the participation of 1-diazopropan-2-one in polar 32CA reactions. A Bonding Evolution Theory (BET) study along the more favourable regioisomeric reaction path associated to the 32CA reaction allows an explanation of its molecular mechanism. The present MEDT study sheds light on these complex domino reactions as well as on the participation of diazoalkanes in polar 32CA reactions towards strong electrophilic ethylenes via a two-stage one-step mechanism.
Habib El Alaoui El Abdallaoui - One of the best experts on this subject based on the ideXlab platform.
-
a molecular electron density theory investigation of the molecular mechanism regioselectivity stereoselectivity and chemoselectivity of cycloaddition reaction between acetonitrile n oxide and 2 5 dimethyl 2h 1 2 3 diazarsole
Theoretical Chemistry Accounts, 2020Co-Authors: Abdellah Zeroual, Mar Riosgutierrez, Mohammed Salah, Habib El Alaoui El Abdallaoui, Mohamed El Ghozlani, Mohammed El Idrissi, Anas Ouled Aitouna, Luis R. DomingoAbstract:The cycloaddition reactions (32CA) of acetonitrile N-oxide and 2,5-dimethyl-2H-[1,2,3]diazarsole 1 have been examined employing the molecular electron density theory through DFT calculations at the B3LYP/6-31G ++(d,p) Computational Level. Investigation of the relative energies related to the competitive ortho and meta reaction paths demonstrates a high chemo-, stereo- and regioselectivity for this 32CA reaction in clear conformity with the experimental results. The topological study of the electron localisation function of the certain points of the IRC associated with the construction of the As–C and C–O single bonds shows a zwitterionic-type structure. The 32CA reaction takes place via a two-stage one-step mechanism initialised with the formation of the As–C single bond.
-
an investigation of the molecular mechanism chemoselectivity and regioselectivity of cycloaddition reaction between acetonitrile n oxide and 2 5 dimethyl 2h 1 2 3 diazaphosphole a medt study
Journal of Chemical Sciences, 2019Co-Authors: Abdellah Zeroual, Mar Riosgutierrez, Mohammed Salah, Habib El Alaoui El Abdallaoui, Luis R. DomingoAbstract:The [3+2] cycloaddition (32CA) reactions of acetonitrile N-oxide with 2,5-dimethyl-2H-[1,2,3]diazaphosphole has been studied using the Molecular Electron Density Theory (MEDT) through DFT calculations at the B3LYP/6-31G(d,p) Computational Level. Analysis of the relative free energies associated with the competitive ortho and meta reaction paths shows high chemo- and regioselectivity for this 32CA reaction in clear agreement with the experimental outcomes. The topological analysis of the electron localization function (ELF) of the selected points of the IRC associated with the formation of the P-C and C-O single bonds indicates a zwitterionic type structure. The 32CA reaction takes place through a two-stage one-step mechanism initialized with the formation of the P-C single bond. The mechanism, the chemo-, and regioselectivity of the [3+2] cycloaddition (32CA) reaction between ethylnitrile oxide and 2,5-dimethyl-2H-[1,2,3]diazaphosphole, have been theoretically studied at the DFT/ B3LYP/6-31(d,p) Computational Level. DFT calculations account for the total chemo- and regioselectivity in total conformity with the experimental results.
-
the role of the polarity on the mechanism and selectivity in the 3 2 cycloaddition reaction between cf3 ynone ylide and azide group a quantum chemical investigation
Journal of Fluorine Chemistry, 2019Co-Authors: Abdelilah Benallou, Zouhair Lakbaibi, Hocine Garmes, Habib El Alaoui El AbdallaouiAbstract:Abstract The goal of the present study is to make a comprehension of the connection between selectivity and polarity, in that fact this reaction process was studied in presence of toluene, THF and DMSO solvent through Molecular Electron Density Theory (MEDT) at the B3LYP/6-31+G(d,p) Computational Level. A remarkable predominance of 4-trifluoroacetyl-1,2,3-triazoles derivatives (P3) has been generated via [3 + 2] cycloaddition between CF3-ynone and azide ylide, rationalized by the electrophilic P+ and nucleophilic P− Parr functions at the reactive sites of reagents, affording the N3-C1 regioselectivity observed experimentally. Furthermore, an exploration of the relative energies of reaction, Gibbs free energy and barrier activation profile obviously evidences that experimentally isolated P3 is the most reachable product of this reaction, in good to excellent yield with respect to the increase of polarity. Moreover, ELF topology analysis of the most stable product demonstrates that the formation of new bonds appears to be directed through two dissimilar fashions, the first is formed by donation of some nitrogen non-bonding electron-density to the carbon pseudoradical center and, the second is formed by sharing nitrogen non-bonding electron-density and a carbon pseudoradical center via a non-concerted two-stage one-step molecular mechanism.
Ibon Alkorta - One of the best experts on this subject based on the ideXlab platform.
-
rivalry between regium and hydrogen bonds established within diatomic coinage molecules and lewis acids bases
ChemPhysChem, 2020Co-Authors: Goar Sanchezsanz, Ibon Alkorta, Cristina Trujillo, José ElgueroAbstract:A theoretical study of the complexes formed by Ag 2 and Cu 2 with different molecules, XH (FH, ClH, OH 2 , SH 2 , HCN, HNC, HCCH, NH 3 and PH 3 ) that can act as hydrogen bond donors (Lewis acids) or regium bond acceptors (Lewis bases) were carried out at the CCSD(T)/CBS Computational Level. In addition, the heteronuclear diatomic coinage molecules (AuAg, AuCu, and AgCu) have also been considered. With the exception of some of the hydrogen bonded complexes with FH, the regium bonded binary complexes are more stable. The AuAg and AuCu molecules show large dipole moments that weaken the RB bonds with Au and favours those through the Ag and Cu atoms respectively.
-
Hydrogen vs. Halogen Bonds in 1-Halo-Closo-Carboranes.
Materials, 2020Co-Authors: Ibon Alkorta, José Elguero, Josep M. Oliva-enrichAbstract:A theoretical study of the hydrogen bond (HB) and halogen bond (XB) complexes between 1-halo-closo-carboranes and hydrogen cyanide (NCH) as HB and XB probe has been carried out at the MP2 Computational Level. The energy results show that the HB complexes are more stable than the XBs for the same system, with the exception of the isoenergetic iodine derivatives. The analysis of the electron density with the quantum theory of atoms in molecules (QTAIM) shows the presence of a unique intermolecular bond critical point with the typical features of weak noncovalent interactions (small values of the electron density and positive Laplacian and total energy density). The natural energy decomposition analysis (NEDA) of the complexes shows that the HB and XB complexes are dominated by the charge-transfer and polarization terms, respectively. The work has been complemented with a search in the CSD database of analogous complexes and the comparison of the results, with those of the 1-halobenzene:NCH complexes showing smaller binding energies and larger intermolecular distances as compared to the 1-halo-closo-carboranes:NCH complexes.
-
lin tetracyanoethylene n 1 4 systems lithium salt vs lithium electride
Computational and Theoretical Chemistry, 2019Co-Authors: Navid Salehi, Ladan Edjlali, Esmail Vessally, Ibon Alkorta, Moosa EshaghiAbstract:Abstract Electrides are interesting and promising materials with cavity-trapped electrons which can be used as source of electron donor in different systems. Hereby, we have explored the possible formation of electride materials based on tetracyanoethylene (TCNE) backbone at MP2 Computational Level. This is achieved by systematic addition of up to four Li atoms to TCNE backbone. Our results predict high thermodynamic stability in the Lin@TCNE (n = 1–4) systems. Moreover, based on the evaluation of four criteria, non-nuclear attractor (NNA), electron localization function (ELF), electron density laplacian ( ∇ 2 ρ ( r ) ) , and non-linear optical (NLO), TCNE-Li1 and TCNE-Li2 and TCNE-Li4 species are conventional donor-acceptor systems (lithium salt). In contrast, the TCNE-Li3 species can be introduced as lithium electride with cavity-trapped electrons. Therefore, Li:TCNE ratio is very significant factor to provide species with electride feature through the addition of Li atoms to TCNE backbone.
-
The influence of halogen bonds on tautomerism: the case of 3-mercapto-1,2-azoles (pyrazoles, isoxazoles, isothiazoles)
Structural Chemistry, 2015Co-Authors: Marta Marín-luna, Ibon Alkorta, José ElgueroAbstract:DFT calculations at the B3LYP/6-311++G(d,p) Computational Level have been carried out on three tautomeric pairs of 3-mercapto-1,2-azoles (pyrazoles, isoxazoles, and isothiazoles) to study the effect of halogen bonds (XBs) on the position of the equilibrium. As halogen bond donors, we have selected Br_2, Cl_2, BrCl, ClF and BrF and compare them with HF as a hydrogen bond donor. Several linear relationships were found between binding energies of different halogen bond donors. The main conclusion of this study is that the XB inverts the tautomeric equilibrium while an HB does not.
-
an exploration of the ozone dimer potential energy surface
Journal of Chemical Physics, 2014Co-Authors: Luis Miguel Azofra, Ibon Alkorta, Stefan ScheinerAbstract:The (O3)2 dimer potential energy surface is thoroughly explored at the ab initio CCSD(T) Computational Level. Five minima are characterized with binding energies between 0.35 and 2.24 kcal/mol. The most stable may be characterized as slipped parallel, with the two O3 monomers situated in parallel planes. Partitioning of the interaction energy points to dispersion and exchange as the prime contributors to the stability, with varying contributions from electrostatic energy, which is repulsive in one case. Atoms in Molecules analysis of the wavefunction presents specific O⋯O bonding interactions, whose number is related to the overall stability of each dimer. All internal vibrational frequencies are shifted to the red by dimerization, particularly the antisymmetric stretching mode whose shift is as high as 111 cm−1. In addition to the five minima, 11 higher-order stationary points are identified.