LANL2DZ Basis Set Research Articles

Strong, near-infrared absorbing porphyrins: a DFT study

A systematic density functional theory study of electronic properties and optical spectra of four potential fused porphyrins with extended π-conjugation has been reported employing the M06 functional along with 6-31G(d)+LanL2DZ basis set. Symmetrical tetra fusion of the benzene rings at the β-meso-β position of porphyrins, resulted in four quadruply fused porphyrins. Such studies revealed the fact that the ring fusion with extended π-electrons causes remarkable red-shifts with narrowed band gaps. Thus, such systems can be used to extend the absorption deeper in to near-infrared (NIR) to even better utilize the photon rich region of solar spectrum. These fused porphyrins have emerged as promising NIR absorbing materials, having utility in molecular solar-conversion systems.

Structural, spectral and optical properties of rocksalt Al,Mn-doped CdO: experimental and DFT studies

Nano-crystalline Cd0.95−x Mn0.05 Alx O (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) semiconductors were synthesized by sol-gel technique. These samples are characterized via X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR) methods. XRD analyses show that the samples have pure rocksalt structure, which is typical for cadmium oxide (CdO). SEM micrographs show that the Al,Mn-doped CdO nanoparticles are cubic with rocksalt structures. The presence of bands at 499, 615 and 660 cm−1 observed in the FTIR spectrum correspond to the stretching of CdO. In addition, the optical properties of nanoparticles were performed as experimentally and theoretically. The optical band gaps of nanoparticles were measured between 1.87 and 2.34 eV, while calculated as 1.19 eV for Mn-doped CdO nanoparticle and 2.13 eV for Mn,Al-doped CdO nanoparticle at lanl2dz and pm6 basis sets. The optical studies showed that the Mn-doped reduces band gap, while Al-doped increases.

Synthesis, characterization and DFT studies of a palladium (ii) complex with bidentate Schiff base ligands

The N-donor bidentate complexes of Palladium (II) of the type [PdL1Cl2] and [PdL2Cl2] {where L1 = N, N'-bis(napthanidal)-1,4-diacetyldihydiimine and L2= N, N'-bis(napthanidal)-1,2-ethylenediimine} were synthesized by refluxing of PdCl2 in acetonitrile with ligand L1 and L2. Complexes have been characterized by elemental analysis, conductivity measurement, IR, UV-Vis and 1H-NMR spectroscopy. Full geometry optimization of the ground state of the complex [PdL1Cl2] was carried out using Density Functional Theory (DFT) at B3LYP functional with 6-311G(d, p) basis set for C, N, Cl, H and LANL2DZ basis set for Pd atoms in gas and solvent (DMSO) phases. The calculated geometric and spectral results reproduced the experimental data with well agreement. Theo-retical calculated molecular orbitals (HOMO–LUMO) and their energies have been calculated that suggest charge transfer occurs within the complexes. The HOMO-LUMO energy gap was found 2.6210 eV. The electrophilic and nucleophilic sites are theoretically evaluated by molecular electrostatic potential. Â

Ab initio study of mechanism of forming a Si-heterocyclic spiro-Sn-heterocyclic ring compound by cycloaddition reaction of Me2Si=Sn: and ethene

X2Si=Sn: (X = H, Me, F, Cl, Br, Ph, Ar, etc.) are a new chemical species. The cycloaddition reactions of X2Si=Sn: are a new field of stannylene chemistry. The mechanism of the cycloaddition reaction between singlet state Me2Si=Sn: and ethene has been investigated for the first time here using second-order Møller-Plesset perturbation theory together with the 6-311++G** basis set for C, H and Si atoms and the LanL2dz basis set for Sn atoms. From the potential energy profile, it could be predicted that the reaction has one dominant reaction channel. The reaction process presented is that the 5p unoccupied orbital of Sn in Me2Si=Sn: and the π orbital of ethene form a π → p donor–acceptor bond resulting in the formation of an intermediate. The instability of this intermediate makes it isomerize to a four-membered Si-heterocyclic ring stannylene. Because the 5p unoccupied orbital of the Sn atom in the four-membered Si-heterocyclic ring stannylene and the π orbital of ethene form a π → p donor–acceptor bond, the four-membered Si-heterocyclic ring stannylene further combines with ethene to form another intermediate. Because the Sn atom in this intermediate assumes sp3 hybridization after the transition state, the intermediate isomerizes to a Si-heterocyclic spiro-Sn-heterocyclic ring compound. This result indicates the modes of cycloaddition reactions between X2Si=Sn: and symmetric π-bonded compounds, i.e. this study opens up a new field for stannylene chemistry.

Crystal structure, spectroscopic characterization, thermal properties and theoretical investigations on [Ag(methyl 4-pyridyl ketone)2NO3

In this paper, we report the synthesis, X-Ray structure, FTIR and thermal characterization, and computational investigations of a silver (I) complex, bis (methyl 4-pyridyl ketone) nitrato silver (I) (I),[ Ag(M4PK)2 NO3] (M4PK = methyl 4-pyridyl ketone, C7H7NO). The silver atom in the complex (I) is surrounded by two N atoms from two methyl 4-pyridyl ketone ligands and one O atom from nitrate ion adopting a distorted T-shaped geometry. The molecular geometry was also optimized by using density functional theory (DFT/B3LYP) methods with the LANL2DZ basis set and geometric parameters were compared with the experimental data. The complete assignments of all vibrational frequencies were performed by potential energy distributions by using SQM program. Molecular electrostatic potential (MEP) distribution, frontier molecular orbitals, non-linear optical properties, thermodynamic parameters, charge analysis of the title compound were also investigated. The thermodynamic parameters of the crystal at different temperature were calculated, revealing the correlations between standard heat capacity, entropy, enthalpy changes and temperature.

Crystal Structure, DFT and Molecular Docking Studies of tris[N-(2-Furylmethyl)-3-Methoxy Salicylidenaminato]Cobalt(III)

A tris[N-(2-fv4rylmethyl)-3-methoxy-salicylidenaminato]cobalt(III) complex is synthesized and characterized by the single crystal X-ray diffraction analysis. The complex crystallizes in the monoclinic space group P21/n with a = 10.8547(4) A, b = 9.5515(3) A, c = 34.2590(10) A, β = 95.246(4)°, V = 3537.0(2) A3, Z = 4. The cationic part of the complex is comprised of a dianionic N2O2-type Schiff base ligand occupying six equatorial positions of an octahedron around the Co(III) ion. Quantum mechanical studies of the complex at the density functional theory (DFT) level with the B3LYP functionals and the LANL2DZ basis set have been reported. The experimental structure and the calculated geometric structure of the complex have been compared. The DFT optimized structures of the complexes agree well with the corresponding X-ray structures. The value of the energy separation between the HOMO and the LUMO is 3.3136 eV. Molecular docking studies of the investigated complex have also been reported that identified the interaction of the Co(III) complex with DNA. The relative binding energy of the docked compound-(B-DNA) is found to be −6.4 kcal/mol. The complex binds at the active site of 1BNA proteins by weak non-covalent interactions, with most prominent of which being conventional π-anion, π-alkyl, CH ⋯ O, and CH ⋯ N.

Synthesis, characterization, theoretical calculations and biochemical evaluation of a novel oxime ligand with complexes

A novel amine containing ketooxime ligand (HBOX) and its Cu(II) and Mn(II) complexes were synthesized, characterized and tested for some of their biological activities. Structural characterization was carried out by elemental analysis, ICP-OES, 1H and 13C NMR, UV–Vis, FT-IR, XRD, TG-DTG, magnetic susceptibility and molar conductivity measurements. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal:ligand ratio was found to be 1:2 and the metal ions were coordinated to the oxime oxygen and amine nitrogen atoms. Furthermore, DFT/B3LYP method with 6-311G(d,p) and LANL2DZ basis sets were used for full optimization of molecular geometries of the ligand and complexes, respectively. The vibrational frequencies, isotropic chemical shifts (1H and 13C NMR), electronic transition absorption wavelengths, HOMO and LUMO analyses and molecular electrostatic potential (MEP) properties of the synthesized molecules have been calculated. The results obtained experimentally were confirmed by the theoretical data which are in good agreement. Inhibitory capacity of the HBOX was investigated against neoangiogenic factors, vascular endothelial growth factor receptor-2 (VEGFR-2) and cyclooxygenase-2 (COX-2) by molecular docking studies. HBOX bound to COX-2 protein with 2 hydrogen bonds at the lowest energy level which indicates the most stabilized form of the protein ligand complex. Complexes were also tested for their catecholase and phenoxazinone synthase-like activities using spectrophotometric procedures. Catecholase and phenoxazinone synthase-like enzyme activities were spectrophotometrically followed by the increase in absorbance at 400 and 433nm resulted from the oxidation reaction of 3,5-di-tert-butylcatechol and 2-aminophenol to 3,5-di-tert-butylquinone and 2-aminophenoxazine-3-one, respectively. According to the calculated kobs values, the Mn(II) complex was found to be more active for both enzymes compared to Cu(II).

The Geometries and Stabilities of Neutral and Anionic Vanadium Doped Germanium Clusters VGen0/-( n = 9 - 13): Density Functional Theory Investigations

The Geometries and Stabilities of Neutral and Anionic Vanadium Doped Germanium Clusters VGen0/-( n = 9 - 13): Density Functional Theory Investigations

Synthesis, characterization, DFT calculations and catalase-like enzymatic activities of novel hexadentate Schiff base and its manganese complexes

We reported the synthesis of the manganese(II) and manganese(III) complexes of a novel hexadentate Schiff base ligand (HBME) (1) obtained from the condensation of triethylenetetramine and 2 equiv. of 1-(biphenyl)-2-hydroxyimino-2-(morpholino)-1-ethanone. Hexadentate Schiff base ligand reacted with manganese(II) perchlorate or manganese(III) acetate and sodium azide, to give rise to a series of mono and dinuclear complexes [Mn(BME)2tren)] (2), [Mn2(BME)2tren(N3)2] (3) and [Mn2(BME)2tren(N3)4] (4). Synthesized molecules were characterized by elemental analyses, ICP-MS, spectroscopic studies, thermal analyses, molar conductivity and magnetic susceptibility measurements. The quantum chemical calculations of the HBME and complexes (2–4) were performed in the ground state using the DFT of B3LYP level with 6-311G(d,p) and LanL2DZ basis sets, respectively. 1H and 13C NMR chemical shifts were calculated by using the gauge independent atomic orbital (GIAO) method and the electronic properties such as HOMO-LUMO energies were determined by the time-dependent DFT approach. The calculated spectroscopic values for the HBME were in very good agreement with experimental ones. Furthermore, catalytic activity of the complexes for the disproportionation of hydrogen peroxide was also investigated in the presence of 1-methylimidazole. All the complexes displayed catalytic activity for the disproportionation of H2O2 significantly, but the activities of the (3) and (4) were relatively higher than the other molecules.

A new palladium(II) complex with ibuprofen: Spectroscopic characterization, DFT studies, antibacterial activities and interaction with biomolecules

This work describes the synthesis, characterization and antibacterial activities of a palladium(II) complex with ibuprofen (ibu). Elemental and mass spectrometric data (ESI-QTOF-MS) suggest a 1:2 metal/ligand composition with the minimal formula PdC26H34O4. Infrared (IR) and nuclear magnetic resonance (NMR) spectroscopic measurements indicate ligand coordination to palladium(II) by the carboxylate group in a bidentate mode. Thermal analysis shows that decomposition of the Pd-ibu complex starts at 130 °C and occurs in three exothermic stages. The steps are consistent with the loss of two ibuprofen molecules, with the formation of the final residue of the thermal treatment at 850 °C. DFT calculations (LANL2DZ basis set), supported by the spectroscopic data, led to an optimized dimeric structure for the complex, where two palladium(II) centers are interconnected by four carboxylates in a cage-like structure. The palladium(II) complex with ibuprofen (Pd-ibu) is soluble in dimethylsulfoxide (DMSO) and hexane and is slightly soluble in ethanol and acetonitrile. The complex exhibited antibacterial activities against Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains, which is noteworthy in the search of new antibacterial agents. Strong interactions were evidenced with biomolecules such as deoxyribonucleic acid (DNA) and bovine serum albumin (BSA) using agarose gel electrophoresis and fluorescence assays, respectively, which suggests that such molecules are possible targets for the complex in biological medium.

A theoretical study on molecular structure, chemical reactivity and molecular docking studies on dalbergin and methyldalbergin

This work deals with the theoretical study on the molecular structure of two well known natural products: dalbergin (DLBG) and methyldalbergin (MDLBG). DLBG and MDLBG, a type of neoflavonoids, have a variety of biological activities: anti-osteoporotic, tumor-specific cytotoxicity, antibacterial, antioxidant actions, antiulcergenic and anti-inflammatory. Computational study on molecular properties of title molecules is presented using density functional theory (DFT) with B3LYP functional and 6-311++G(d,p) and LanL2DZ basis set. Molecular electrostatic potential surface (MEPS) and electronic reactivity descriptors were used to understand the role of interactions involved in affecting the chemical reactivity of both molecules. Natural bond orbital (NBO) analysis predicted the stability of molecules due to charge delocalization and hyper conjugative interactions. Natural bond orbital studies were performed to investigate the intramolecular charge transfer that results in molecular stability, and π → π* transition. Molecular docking studies show that the title molecules exhibit an antiosteoporotic and antibacterial activity.

New mixed amino acids complexes of iron(III) and zinc(II) with isonitrosoacetophenone: Synthesis, spectral characterization, DFT study and anticancer activity

New mixed Fe(III) and Zn(II) complexes with isonitrosoacetophenone (HINAP) and l-amino acids (such as l-histidine, l-phenylalanine and l-proline) have been synthesized and characterized by elemental analyses, UV-Vis, IR and ESR spectroscopy and thermal analyses. The values of molar conductance of the complexes in DMSO solution at 10-3 M concentration indicate their non-electrolyte nature. IR spectroscopy has revealed the coordination of deprotonated ligands to metal through nitrogen and oxygen atoms in an N2O2 arrangement. Density functional theory (DFT) calculations were performed using the hybrid functional of Truhlar and Zhao (M06) with basis set of double zeta quality LANL2DZ to evaluate the cis and trans coordination modes and to ascertain dipole moment, HOMO-LUMO energy gap, chemical hardness, softness and electrophilicity. The magnetic moments and ESR measurements suggest that there is an admixture of S = 5/2 and S = 1/2 spins in Fe(III) complexes. UV-Visible spectra indicate a distorted octahedral geometry around the metal ions. Thermal analyses show the presence of hydrated and coordinated water. The antimicrobial activity was investigated against (G+ and G-) bacteria (Staphylococcus aureus, bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa) and fungi (Candida albicans). The iron and zinc complexes were found to be more active against Gram-positive than Gram negative bacteria. They also show considerable growth inhibition against the fungi tested. In vitro antitumor activity assayed against cancer cell lines of the HEP2 type (cancer cells of the larynx) exhibited significant toxicity of the ligands and their mixed complexes.

Reduction Potential Predictions for Some 3-Aryl-Quinoxaline-2-Carbonitrile 1,4-Di-N-Oxide Derivatives with Known Anti-Tumor Properties

The ability for DFT: B3LYP calculations using the 6-31g and lanl2dz basis sets to predict the electrochemical properties of twenty (20) 3-aryl-quinoxaline-2-carbonitrile 1,4-di-N-oxide derivatives with varying degrees of cytotoxic activity in dimethylformamide (DMF) was investigated. There was a strong correlation for the first reduction and moderate-to-low correlation of the second reduction of the diazine ring between the computational and the experimental data, with the exception of the derivative containing the nitro functionality. The four (4) nitro group derivatives are clear outliers in the overall data sets and the derivative E4 is ill-behaved. The remaining three (3) derivatives containing the nitro groups had a strong correlation between the computational and experimental data; however, the computational data falls substantially outside of the expected range.

Palladium(II) complexes containing seven halogeno-derivatives of 7-azaindole: molecular structures, vibrational spectra, DFT calculations and in vitro cytotoxic activity

In the present work seven new complexes of Pd(II) containing halogeno-derivatives of 7-azaindole (7AIH), [PdCl2(L)2], where L = 3-chloro-7-azaindole (3Cl7AIH) or 3-bromo-7-azaindole (3Br7AIH) or 4-chloro-7-azaindole (4Cl7AIH) or 4-bromo-7-azaindole (4Br7AIH) or 5-bromo-7-azaindole (5Br7AIH) or 3-bromo-4-chloro-7-azaindole (3Br4Cl7AIH) or 5-bromo-3-chloro-7-azaindole (5Br3Cl7AIH) were prepared and studied by infrared and Raman spectroscopy accompanied by the DFT calculations. Full geometry optimizations and vibrational frequency calculations were performed for the two possible isomers cis and trans of [PdCl2(L)2] using the B3LYP method with the 6–311++G(d,p)/LanL2DZ basis sets. According to the theoretical results, the trans isomers are more stable than cis. As shown by the combined experimental and theoretical vibrational spectroscopic studies, only trans isomers with Ci symmetry are present, in the solid state. The combined experimental and theoretical studies have revealed that in [PdCl2(L)2] complexes, palladium(II) is bound to two pyridine nitrogen atoms of L ligands and to two chloride ions, in a square-planar trans arrangement. Detailed vibrational assignments of the experimental infrared and Raman spectra of these complexes have been made on the basis of the calculated potential energy distributions (PEDs). The antiproliferative activity of selected trans-[PdCl2(L)2] have been tested against human cancer cell lines (T47D, MCF7, A549 and A2780). The obtained IC50 values indicate that the title complexes possess lower cytotoxicity, in comparison to cisplatin.

Crystal structure, DFT and molecular docking studies of tris[N-(2-furylmethyl)-3-methoxy salicylidenaminato]cobalt(III)

A tris[N-(2-furylmethyl)-3-methoxy-salicylidenaminato]cobalt(III) complex is synthesized and characterized by the single crystal X-ray diffraction analysis. The complex crystallizes in the monoclinic space group P21/n with a = 10.8547(4), b = 9.5515(3), c = 34.2590(10) Å, β = 95.246(4)°, V = 3537.0(2) Å3, Z = 4. The cationic part of the complex is comprised of a dianionic N2O2-type Schiff base ligand occupying six equatorial positions of an octahedron around the Co(III) ion. Quantum mechanical studies of the complex at the density functional theory (DFT) level with the B3LYP functionals and the LANL2DZ basis set have been reported. The experimental structure and the calculated geometric structure of the complex have been compared. The DFT optimized structures of the complexes agree well with the corresponding X-ray structures. The value of the energy separation between the HOMO and the LUMO is 3.3136 eV. Molecular docking studies of the investigated complex have also been reported that identified the interaction of the Co(III) complex with DNA. The relative binding energy of the docked compound-(B-DNA) is found to be –6.4 kcal/mol. The complex binds at the active site of 1BNA proteins by weak non-covalent interactions, with most prominent of which being conventional π-anion, π-alkyl, CH⋯O, and CH⋯N.

Ternary Copper (II) complex based chemical probes for DNA targeting: Cytotoxic activity under visible light

Among the bio‐metals, copper derivatives of O, N, S donor salicylaldehyde thiosemicarbazones have been obtained large interest due to their potential biological applications. Multisubstituted thiosemicarbazone ligand HL derived, new ternary Cu (II) complexes of [Cu(L)(bpy)] (1) and [Cu(L)(phen)] (2) (where, bpy is 2,2′‐bipyridine and phen is 1,10‐phenanthroline) have been synthesized and characterized using different physico‐chemical techniques. Complexes 1 and 2 are structurally characterized by single crystal X‐ray diffraction analysis, which reveals the trigonal bipyramidal distorted square based pyramid geometry of both the complexes 1 and 2 with ONS‐donor thiosemicarbazone bonded at the upper plane. The ground state electronic structures of complexes 1 and 2 have been investigated by using DFT/B3LYP theoretical evaluation with 6‐31G (d,p) and LANL2DZ basis set. The affinity towards DNA and human serum albumin has been evaluated using computational docking analysis and complex 2 exposes significant binding ability towards DNA and human serum albumin, because of its immense hydrophobicity. Consequently, complex 2 have higher antimicrobial in addition to the cytotoxic activity than complex 1 and free ligand HL under visible light. Along with, their apoptosis pathway of cytotoxicity has been evaluated by fluorescent microscopic analysis using acridine orange/ethidium bromide (AO/EB) stains. From these preliminary investigations, we believe that complex 2 can play a role as a more robust pharmacological agent.

Experimental and theoretical investigations of 4-hydroxy L-proline cadmium chloride nonlinear optical crystal

The solution grown structure 4-hydroxy L-proline cadmium chloride (4HLPCC) single crystal has been done by means of X-ray diffraction method. The computational quantum mechanical modelling method was performed with B3LYP level and LanL2DZ basis set to determine optimized geometry, dipolar moment, linear polarizability, first order hyperpolarizability, atomic charges of various atoms, thermodynamic parameters, HOMO-LUMO energy gap and vibrational frequencies of 4HLPCC. The vibrational frequencies of 4HLPCC were observed experimentally through FTIR and FT-RAMAN analyses and compared with theoretical frequencies. The electric properties were detected by dielectric studies. The frequency doubling of the grown crystal was made with Kurtz-Perry powder technique.

First-principles calculations of gold and silver clusters doped with lithium atoms

This study focuses on bimetallic clusters of Aun-1Lix, Agn-1Lix for (n = 2–19, x = 1,2) optimized with the computational Gaussian 09 package using the Ab initio calculations and the density functional theory (DFT) with the hybrid functional B3LYP and the basis set LanL2DZ. The paper presents the calculations of the following stability parameters: vertical ionization potential (VIP), vertical electron affinity (VEA), chemical hardness, chemical potential, second energy difference, the difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). An odd-even oscillation tendency was observed. The hardness of the gold clusters increased when they were doped with a single Li atom. The hardness of the gold clusters doped with two Li atoms increased significantly for clusters Au2Li2, Au3Li2, Au6Li and Au7Li2, Ag2Li2, Ag4Li2, Ag6Li2 and Ag16Li2. Other Magic Number Clusters were identified.

Dft Calculations and Spectroscopic Studies of some Ni Dimethylglyoximebased Complexes Isolated by the Hydrothermal Process

In this paper, we report the synthesis of dimethylglyoximato-nickel complexes by the hydrothermal method. This process is rarely used for the preparation of coordination compounds. In order to identify the oxidation state of nickel within the complexes, the complexation study was conducted in two ways (with or without an oxidizing chemical agent, namely potassium persulfate). New mononuclear dimethylglyoxime–nickel complexes are isolated and thoroughly characterized by elemental analyses and commonly used spectral techniques. The EPR investigation confirms the oxidation state of nickel in all complexes. Infrared spectroscopy (IR) and nuclear magnetic resonances (1H and 13C) indicate the formation and presence of new reduced forms of oximes within the complexes, namely enamine. From all these investigations, the suggested formulas for the complexes are: (Ni(C4H7N2O)2OH), named bis(3-aminobut-3-en-2-one oximato)hydrox nickel(III), noted Ca, obtained without an oxidizing chemical agent and Ni(C4H6N2O)2(OH)2), named bis(3-aminobut-3-en-2-one oximato) dihydroxy nickel(IV), noted Cb, obtained with an oxidizing chemical agent. The experimental IR, 1H and 13C NMR results and the electronic spectra (UV) are compared to those obtained theoretically by the DFT method, with the B3LYP function and the LANL2DZ basis set. The energy, structural, and electronic parameters are determined for the ligand and each complex studied. Binding energies are also theoretically evaluated for each complex.

An efficient protocol for the synthesis of thioethers via iron-catalyzed cross-coupling reaction and its mechanistic investigation

One of the most straightforward methods for the synthesis of diaryl sulfides is the transition metal catalyzed CS coupling reaction. Herein we report a study on the iron-catalyzed protocol for cross-coupling reaction of aryl halides with thiols. Structurally diverse diaryl sulfides were prepared efficiently by using a catalyst system involving cheap and environment-friendly FeCl3 and non-toxic universal ligand l-proline. The reaction mechanism for the iron-catalyzed CS coupling reaction was investigated by means of density functional theory (DFT) methods on a model system. The calculations were performed using hybrid PBE1PBE functional in conjugation with the LANL-2DZ basis set. The key step involved in the mechanism is the formation of a reactant complex in which both reactants are electrostatically bound to Fe(III) proline complex catalyst. The elimination of HI occurs with a much lower TS energy (20.0 kcal/mol) than the uncatalyzed reaction (44.7 kcal/mol).