Browsing by Subject "DFT calculations"
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- PublicationOpen AccessA structural analysis of 2,5-diaryl-4H-2,4-dihydro-3H-1,2,4-triazol-3-ones: NMR in the solid-state, X-ray crystallography and GIPAW calculations(Wiley, 2021) Marín-Luna, Marta; Sánchez-Andrada, Pilar; Alkorta, Ibon; Elguero, José; Torralba, M. Carmen; Delgado-Martínez, Patricia; Santa María, Dolores; Claramunt, Rosa M.; Química OrgánicaThe 1H, 13C, 15N, and 19F nuclear magnetic resonance (NMR) spectra of 11 2,5-diaryl-2,4-dihydro-3H-1,2,4-triazol-3-ones have been acquired in DMSO-d6 solution and the 13C, 15N, and 19F NMR spectra have also been acquired in the solid state (solid-state nuclear magnetic resonance [SSNMR] and magic angle spinning [MAS]). The X-ray structures of Compounds 3, 5, and 6 have been determined by X-ray diffraction. Theoretical calculations at the gauge-independent atomic orbital (GIAO)/B3LYP/6-311++G(d,p) level have provided a set of 321 chemical shifts that were compared with 310 experimental values in DMSO-d6. To obtain good agreements, some effects need to be included. The SSNMR chemical shifts have been compared with gauge-including projector-augmented wave (GIPAW) calculations and with the heavy atom–light atom (HALA) effects.
- PublicationOpen AccessAccess to ligand-stabilized PH-containing phosphenium complexes(Royal Society of Chemistry, 2024-01-04) Biskup, David; Schnakenburg, Gregor; Espinosa Ferao, Arturo Francisco; Streubel, Rainer; Química OrgánicaWhile the chemistry of phosphenium compounds, including metal complexes thereof, is very well established, few derivatives having a P–H bond have been described, yet. This work describes rational access to donor-stabilised phosphenium metal complexes possessing a P–H bond using protonation reactions of stable phosphinidene complex adducts. While most Brønsted–Lowry acids yield formal 1,1-addition products at the phosphorus centre under the loss of the donor, super-strong acids having weakly coordinating anions enable access to donor-stabilised P–H hosphenium complex salts. The latter possess N-methylimidazole as a donor (to phosphorus) and the N–P interaction has been studied theoretically.
- PublicationOpen AccessCarbonylation of Boranes ¿ A Computational Study(Royal Society of Chemistry, 2023-12-11) Espinosa Ferao, Arturo Francisco; Química OrgánicaThe classical simple picture of stepwise B-to-C migratory insertion of all three alkyl groups in the carbonylation reaction of trialkyl boranes with CO was shown not to be correct, except for the first alkyl group shift affording an acyl borane. The second and third direct alkyl shifts turned out to be kinetically hampered due to the non-activated character of the B C bond in electron-poor B atoms. The latter can only be achieved by either the autocatalytic action of the final alkyl boron oxide or by formation of dimeric species with weakened B-alkyl bonds at borate centres. Both thermodynamic and several NICS-related parameters pointed to scarce, even “negative”, aromatic character for boroxines, the final cyclotrimerization products of alkyl-boron oxides
- PublicationOpen AccessDeoxygenation of Oxiranes by ¿3¿3-Phosphorus Reagents ¿ Computational Mechanistic and Stereochemical Study(Wiley-VCH Gmb, 2023-10-17) Espinosa Ferao, Arturo Francisco; Química OrgánicaThe deoxygenation of parent and substituted oxiranes by λ3 σ3 - phosphorus reagents has been explored in detail, therefore unveiling mechanistic aspects as well as regio- and stereochemical consequences. Attack to a ring C atom is almost always preferred over one-step deoxygenation by direct P-to-O attack. In most cases a carbene transfer occurs as first step, leading to a phosphorane and a carbonyl unit that thereafter react in the usual Wittig fashion via the corresponding λ5 σ5 -1,2- oxaphosphetane intermediate. Betaines rarely constitute true minima after the first C-attack to oxiranes, at least in the gasphase. Use of the heavier derivatives AsMe3 and SbMe3 as oxirane deoxygenating reagents was also mechanistically studied. The thermodynamic tendency of λ3 σ3 -phosphorus reagents to act as oxygen (O-attack) or carbene acceptors (Cattack) was theoretically studied by means of the thermodynamic oxygen-transfer potential (TOP) and the newly defined thermodynamic carbene-transfer potential (TCP) parameters, that were explored in a wider context together with many other acceptor centres.
- PublicationOpen AccessInsight into the Stokes shift, divergent solvatochromism and aggregation-induced emission of boron complexes with locked and unlocked benzophenanthridine ligands(2022-11-10) Mas Montoya, M.; Garcia Alcaraz, A.; Espinosa Ferao, A. F.; Bautista Cerezo, D.; Curiel Casado, D.; Química OrgánicaTwo four-coordinate boron complexes, compounds 5 and 7, have been synthesized, using analogous benzophenanthridine-based ligands but showing different conformational constraints, and their optical properties have been investigated. Following a ligand design that takes into consideration the expansion of π-conjugation and the structural desymmetrization has proved to be a useful approach to obtain fluorophores with large Stokes shifts. The analysis of the Huang-Rhys parameters along with the vibrational modes have revealed that the incorporation of a conformationally free substructure entails an enhanced Stokes shift as a result of an increased geometry relaxation in the first excited state (S1) and the ground state (S0). Additionally, the sensitivity of the Stokes shift to the solvent polarity showed a divergent solvatochromism (bathochromism in emission spectra and hypsochromism in absorption spectra) whose origin has been ascribed by experimental and theoretical methods to the dissimilar extent of the stabilization of S0 and S1 states with respect to the corresponding Franck-Condon states. Besides, the formation of aggregates in dimethylformamide/water mixtures has been related to the solid state packing, determined by X-ray diffraction, to explain the aggregation-induced effects on the emissive properties of the reported organoboron complexes. The less conformationally restricted molecule, 7, displayed aggregation-induced emission (AIE) promoted upon blocking the motion of the peripheral rotor.
- PublicationOpen AccessInterlocking the Catalyst: Thread versus Rotaxane-Mediated Enantiodivergent Michael Addition of Ketones to beta-Nitrostyrene(American Chemical Society, 2019-06-19) Martinez-Cuezva, Alberto; Marin-Luna, Marta; Alonso, Diego A.; Ros-Ñiguez, Diego; Alajarín, Mateo; Berná Cánovas, José; Química OrgánicaFumaramide threads bearing one l-prolinamide fragment have been designed as templates for promoting the efficient formation of novel Leigh’s [2]rotaxanes. Both threads and rotaxanes are shown to catalyze the asymmetric addition of ketones to β-nitrostyrene in an enantio- and diastereoselective manner. Interestingly, the enantioselective course of these processes is reversed simply by changing from thread to rotaxane as catalyst. DFT computations have allowed to rationalize the stereodivergence shown by the interlocked and noninterlocked catalysts.
- PublicationOpen AccessInternal Coulombic Assistance in Intermolecular Frustrated Lewis Pair Activation of Dihydrogen(Royal Society of Chemistry, 2024-02) Rey Planells, Alicia; Espinosa Ferao, Arturo Francisco; Streubel, Rainer; Frontera, Antonio; Química Orgánica1,3-Zwitterions consisting of a phosphonium cation linked to a silicate centre through a one-atom bridge, X3P–E–SiY4 (3), are computationally studied. Their phosphonium acidic group together with a Lewis base constitute a frustrated Lewis pair (FLP) in the activation of H2, with the silicate side-arm providing Coulombic stabilization to the positive charge at the Lewis base.
- PublicationOpen AccessLewis Acid-mediated Formation of 1,3-Disubstituted Spiro[cyclopropane-1,2'-indanes]: The Activating Effect of the Cyclopropane Walsh Orbital(American Chemistry Society, 2020-02) Alajarín, Mateo; Ballester, Francisco-Jose; Vivancos, Juan-Antonio; Orenes, Raul-Angel; Vidal, Angel; Sanchez-Andrada, Pilar; Marin-Luna, Marta; Química OrgánicaBy virtue of its alkylidenecyclopropane moiety 2-(cyclopropylidenemethyl)benzaldehyde reacts with a range of amines or thiols under Lewis acid catalysis yielding the respective 1,3-bis(arylamino) or -bis(arylthio and alkylthio)indanes spirolinked to the cyclopropane ring at carbon 2. The reaction mechanism and the peculiar contribution of the cyclopropane ring have been scrutinized by DFT calculations.
- PublicationOpen AccessRegioselective N- versus P-deprotonation of amino-phosphane tungsten(0) complexes(2022-06-22) Terschüren, T.; Junker, P.; Schmer, A.; Espinosa Ferao, A. F.; Streubel, R.; Química Orgánica1,2-Bifunctional ligands are rare, in general, which holds especially for those with a P-N linkage. Herein, we report on the synthesis of P-tert-butyl substituted aminophosphane W(CO)5 complexes 3a–f (a: R = R’ = H; b: R = H, R = Me; c: R = H, R’ = ally; d: R = H, R’ = i-Pr; e: R = H, R’ = t-Bu; f: R = R’ = Me) obtained via formal N-H insertion reactions of Li/Cl phosphinidenoid complex 2 into NH bonds of ammonia and different amines. The 1,2-bifunctionality of 3b was addressed in targeted regioselective deprotonation reactions leading to amidophosphane complexes M-4b or M/N(H)Me phosphinidenoid complexes M-5b, respectively (M = Li, K). Remarkable was the observation that reactions of M-4b and M-5b with MeI as the electrophile resulted in the formation of the same product 7b. The constitution of all the compounds has been established by means of NMR and IR spectroscopy and mass spectrometry. Two possible reaction pathways were studied in detail using high-level DFT calculations
- PublicationOpen AccessUnlocking the synthetic potential of aziridine and cyclopropane-fused quinolin-2-ones by regioselective fragmentation of its three-membered rings(Elsevier, 2020-01-07) Diaz, Javier; Rodenas, Daniel; Ballester, Francisco J; Alajarín, Mateo; Orenes, Raul A.; Sanchez-Andrada, Pilar; Vidal, Angel; Química OrgánicaThe cyclization of cis-2-(2-azidophenyl)-1-benzyl-3-ethoxycarbonylaziridines and trans-2-(2-azidophenyl)-3-nitrocyclopropane-1,1-dicarboxylates yielded the respective aziridino[2,3-c]quinolin-2-ones and cyclopropa[c]quinolin-2-ones. Ring-opening of the aziridine-fused species under silica gel catalysis provided 3-aminoquinolin-2-ones whereas the ring-expansion of the cyclopropane-fused derivatives by the action of sodium hydride gave 1-benzazepin-2-ones, in both cases in a regioselective manner. A computational study using DFT methods revealed that the mechanism for the transformation of cyclopropa[c]quinolin-2-ones into 1-benzazepin-2-ones involves the initial deprotonation step of its amide function followed by two pericyclic events: a 6π-electrocyclic ring opening and a subsequent [1,5]-H shift.