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- Keyword
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- Ab initio (9)
- SuFEx (6)
- Electron transfer (5)
- Catalysis (4)
- Electronic coupling element (4)
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- Calcium bistriflimide (3)
- Excitation energy (2)
- Generalized Mulliken-Hush method (2)
- Hydrogen bonds (2)
- Low-lying electronic state (2)
- Palladium (2)
- Rotamers (2)
- Sulfonamides (2)
- Sulfonyl fluorides (2)
- Sulfur(VI) fluorides (2)
- Time-dependent density functional theory (2)
- 1-3-5-hexatriene (1)
- 1-3-butadiene (1)
- Ab Initio investigation (1)
- Ab initio calculations (1)
- Adiabatic excitation energy (1)
- Alkali oxides (1)
- All-trans octatetraene (1)
- Anaplastic Lymphoma Kinase (1)
- Anions (1)
- Aryl iodides (1)
- Arylamine-substituted acridinium ion systems (1)
- Assembly lines (1)
- AutoDock Vina (1)
- Biomimetic synthesis (1)
- Publication Year
Articles 1 - 30 of 40
Full-Text Articles in Physical Sciences and Mathematics
Synthesis Of 2-Arylpyridines By The Suzuki–Miyaura Cross-Coupling Of Pyfluor With Hetero (Aryl) Boronic Acids And Esters, Juan Rueda-Espinosa, Dewni Ramanayake, Nicholas Ball, Jennifer A. Love
Synthesis Of 2-Arylpyridines By The Suzuki–Miyaura Cross-Coupling Of Pyfluor With Hetero (Aryl) Boronic Acids And Esters, Juan Rueda-Espinosa, Dewni Ramanayake, Nicholas Ball, Jennifer A. Love
Pomona Faculty Publications and Research
The Suzuki–Miyaura cross-coupling of pyridine-2-sulfonyl fluoride (PyFluor) with hetero(aryl) boronic acids and pinacol boronic esters is reported. The reactions can be performed using Pd(dppf)Cl2 as the catalyst, at temperatures between 65 and 100 °C and in the presence of water and oxygen. This transformation generates 2-arylpyridines in modest to good yields (5%–89%).
Calcium Bistriflimide-Mediated Sulfur (Vi)–Fluoride Exchange (Sufex): Mechanistic Insights Toward Instigating Catalysis, Nicholas Ball, Brian Han, Samuel R. Khasnavis, Matthew Nwerem, Michael Bertagna, O Maduka Ogba
Calcium Bistriflimide-Mediated Sulfur (Vi)–Fluoride Exchange (Sufex): Mechanistic Insights Toward Instigating Catalysis, Nicholas Ball, Brian Han, Samuel R. Khasnavis, Matthew Nwerem, Michael Bertagna, O Maduka Ogba
Pomona Faculty Publications and Research
We report a mechanistic investigation of calcium bistriflimide-mediated sulfur(VI)–fluoride exchange (SuFEx) between sulfonyl fluorides and amines. We determine the likely pre-activation resting state─a calcium bistriflimide complex with ligated amines─thus allowing for corroborated calculation of the SuFEx activation barrier at ∼21 kcal/mol, compared to 21.5 ± 0.14 kcal/mol derived via kinetics experiments. Transition state analysis revealed: (1) a two-point calcium-substrate contact that activates the sulfur(VI) center and stabilizes the leaving fluoride and (2) a 1,4-diazabicyclo[2.2.2]octane additive that provides Brønsted-base activation of the nucleophilic amine. Stable Ca–F complexes upon sulfonamide formation are likely contributors to inhibited catalytic turnover, and a proof-of-principle redesign …
Sulfondiimidamides Unlocked As New S(Vi) Hubs For Synthesis And Drug Discovery, Nicholas Ball
Sulfondiimidamides Unlocked As New S(Vi) Hubs For Synthesis And Drug Discovery, Nicholas Ball
Pomona Faculty Publications and Research
Despite their promise as drug targets, access to nitrogen-rich S(VI) compounds has been a significant synthetic challenge. In this issue of Chem, Zhang and Willis explore a new class of S(VI) compounds-sulfondiimidamides-providing robust strategies toward their synthesis, derivation, and promise as new sulfonamide bioisosteres.
The Emerging Applications Of Sulfur (Vi) Fluorides In Catalysis, Nicholas Ball, Cayo Lee, Jonathan E. Elisabeth, Nathan C. Friede, Glenn M. Sammis
The Emerging Applications Of Sulfur (Vi) Fluorides In Catalysis, Nicholas Ball, Cayo Lee, Jonathan E. Elisabeth, Nathan C. Friede, Glenn M. Sammis
Pomona Faculty Publications and Research
The past decade has witnessed remarkable growth of catalytic transformations in organic sulfur(VI) fluoride chemistry. This Perspective concentrates exclusively on foundational examples that utilize catalytic strategies to synthesize and react S(VI) fluorides. Key mechanistic studies that aim to provide insight toward future catalytic systems are emphasized.
Sufex Activation With Ca(Ntf2)2: A Unified Strategy To Access Sulfamides, Sulfamates, And Sulfonamides From S(Vi) Fluorides, Nicholas Ball, Subham Mahapatra, Cristian P. Woroch, Todd W. Butler, Sabrina N. Carneiro, Sabrina C. Kwan, Samuel R. Khasnavis, Junha Gu, Jason K. Dutra, Beth C. Vetelino, Justin Bellenger, Christopher W. Am Ende
Sufex Activation With Ca(Ntf2)2: A Unified Strategy To Access Sulfamides, Sulfamates, And Sulfonamides From S(Vi) Fluorides, Nicholas Ball, Subham Mahapatra, Cristian P. Woroch, Todd W. Butler, Sabrina N. Carneiro, Sabrina C. Kwan, Samuel R. Khasnavis, Junha Gu, Jason K. Dutra, Beth C. Vetelino, Justin Bellenger, Christopher W. Am Ende
Pomona Faculty Publications and Research
A method to activate sulfamoyl fluorides, fluorosulfates, and sulfonyl fluorides with calcium triflimide and DABCO for SuFEx with amines is described. The reaction was applied to a diverse set of sulfamides, sulfamates, and sulfonamides at room temperature under mild conditions. Additionally, we highlight this transformation to parallel medicinal chemistry to generate a broad array of nitrogen-based S(VI) compounds.
Sulfonamide Synthesis Via Calcium Triflimide Activation Of Sulfonyl Fluorides, Nicholas Ball, Paramita Mukherjee, Cristian P. Woroch, Leah Cleary, Mark Rusznak, Ryan W. Franzese, Matthew R. Reese, Joseph W. Tucker, John M. Humphrey, Sarah M. Etuk, Sabrina C. Kwan, Christopher W. Am Ende
Sulfonamide Synthesis Via Calcium Triflimide Activation Of Sulfonyl Fluorides, Nicholas Ball, Paramita Mukherjee, Cristian P. Woroch, Leah Cleary, Mark Rusznak, Ryan W. Franzese, Matthew R. Reese, Joseph W. Tucker, John M. Humphrey, Sarah M. Etuk, Sabrina C. Kwan, Christopher W. Am Ende
Pomona Faculty Publications and Research
A method using calcium triflimide [Ca(NTf2)2] as a Lewis acid to activate sulfonyl fluorides toward nucleophilic addition with amines is described. The reaction converts a wide array of sterically and electronically diverse sulfonyl fluorides and amines into the corresponding sulfonamides in good yield.
Pd-Catalyzed Conversion Of Aryl Iodides To Sulfonyl Fluorides Using So2 Surrogate Dabso And Selectfluor, Nicholas Ball, Ariana L. Tribby, Ismerai Rodríguez, Shamira Shariffudin
Pd-Catalyzed Conversion Of Aryl Iodides To Sulfonyl Fluorides Using So2 Surrogate Dabso And Selectfluor, Nicholas Ball, Ariana L. Tribby, Ismerai Rodríguez, Shamira Shariffudin
Pomona Faculty Publications and Research
A one-pot Pd-catalyzed conversion of aryl iodide to aryl sulfonyl fluorides using DABSO and Selectfluor has been developed generating aryl sulfonyl fluorides in good to excellent yields. The reaction results in the generation of electronically and sterically diverse sulfonyl fluorides. Additionally, sulfonyl fluorides can be converted to aryl sulfonamides and sulfonic esters using Cs2CO3 under mild conditions.
Small Molecule Inhibitor Design For Anaplastic Lymphoma Kinase Inhibition, Theodore D. Hansel, David J. Grabovsky
Small Molecule Inhibitor Design For Anaplastic Lymphoma Kinase Inhibition, Theodore D. Hansel, David J. Grabovsky
Interface Compendium of Student Work
The Anaplastic Lymphoma Kinase (ALK) gene has been linked to tumorigenesis in a number of human cancers, including anaplastic large cell lymphoma (ALCL) and neuroblastoma. While ALK mutations in ALCL and many other cancers occur as a result of gene fusions with wild type kinase domains, those in neuroblastoma stem from single nucleotide polymorphisms (SNPs) in the kinase domain. These lead to autophosphorylation and constitutive signaling by ALK for cell growth and division, ultimately causing cancer. Crizotinib, an ATP-competitive ALK inhibitor, has proven to be an effective inhibitor of both ALKWT and ALKMutant kinase domains, and is in the middle …
Direct, Biomimetic Synthesis Of (+)-Artemone Via A Stereoselective, Organocatalytic Cyclization, Eric D. Nacsa, Brian C. Fielder, Shannon P. Wetzler, Veerasak Srisuknimit, Jonathan P. Litz, Mary J. Van Vleet, Kim Quach, David A. Vosburg
Direct, Biomimetic Synthesis Of (+)-Artemone Via A Stereoselective, Organocatalytic Cyclization, Eric D. Nacsa, Brian C. Fielder, Shannon P. Wetzler, Veerasak Srisuknimit, Jonathan P. Litz, Mary J. Van Vleet, Kim Quach, David A. Vosburg
All HMC Faculty Publications and Research
We present a four-step synthesis of (+)-artemone from (–)- linalool, featuring iminium organocatalysis of a doubly diastereoselective conjugate addition reaction. The strategy follows a proposed biosynthetic pathway, rapidly generates stereochemical complexity, uses no protecting groups, and minimizes redox manipulations.
Emerging Solar Cell Technology: Advances In Solid-State Polymer Hybrid Dye-Sensitized Solar Cells, Andrew De Jong
Emerging Solar Cell Technology: Advances In Solid-State Polymer Hybrid Dye-Sensitized Solar Cells, Andrew De Jong
Environmental Analysis Program Mellon Student Summer Research Reports
Mr. de Jong worked at Oxford University to extend solid-state solar cells’ photoresponse by taking advantage of a favorable energy-transfer mechanism.
A Topological Approach To Molecular Chirality, Erica Flapan
A Topological Approach To Molecular Chirality, Erica Flapan
Pomona Faculty Publications and Research
Topology is the study of deformations of geometric figures. Chemistry is the study of molecular structures. At first glance these fields seem to have nothing in common. But let’s take a closer look to see how these fields come together in the study of molecular symmetries.
Reduced Electronic Spaces For Modeling Donor/Acceptor Interactions, Robert J. Cave, Stephen T. Edwards '06, John A, Kouzelos '07, Marshall D. Newton
Reduced Electronic Spaces For Modeling Donor/Acceptor Interactions, Robert J. Cave, Stephen T. Edwards '06, John A, Kouzelos '07, Marshall D. Newton
All HMC Faculty Publications and Research
Diabatic states for donor (D) and acceptor (A) interactions in electron transfer (ET) processes are formulated and evaluated, along with coupling elements (HDA) and effective D/A separation distances (rDA), for reduced electronic spaces of variable size, using the generalized Mulliken Hush model (GMH), applicable to an arbitrary state space and nuclear configuration, and encompassing Robin−Day class III and as well as class II situations. Once the electronic state space is selected (a set of n ≥ 2 adiabatic states approximated by an orbital space based on an effective 1-electron (1-e) Hamiltonian), the charge-localized GMH …
The Initial And Final States Of Electron And Energy Transfer Processes: Diabatization As Motivated By System-Solvent Interactions, Joseph E. Subotnik, Robert J. Cave, Ryan P. Steele, Neil Shenvi
The Initial And Final States Of Electron And Energy Transfer Processes: Diabatization As Motivated By System-Solvent Interactions, Joseph E. Subotnik, Robert J. Cave, Ryan P. Steele, Neil Shenvi
All HMC Faculty Publications and Research
For a system which undergoes electron or energy transfer in a polar solvent, we define the diabatic states to be the initial and final states of the system, before and after the nonequilibrium transfer process. We consider two models for the system-solvent interactions: A solvent which is linearly polarized in space and a solvent which responds linearly to the system. From these models, we derive two new schemes for obtaining diabatic states from ab initio calculations of the isolated system in the absence of solvent. These algorithms resemble standard approaches for orbital localization, namely, the Boys and Edmiston–Ruedenberg (ER) formalisms. …
Tunneling Through Weak Interactions: Comparison Of Through-Space-, H-Bond-, And Through-Bond-Mediated Tunneling, Westin Kurlancheek '03, Robert J. Cave
Tunneling Through Weak Interactions: Comparison Of Through-Space-, H-Bond-, And Through-Bond-Mediated Tunneling, Westin Kurlancheek '03, Robert J. Cave
All HMC Faculty Publications and Research
Results from ab initio electronic structure theory calculations on model systems allow for the detailed comparison of tunneling through covalently bonded contacts, hydrogen bonds, and van der Waals contacts. Considerable geometrical sensitivity as well as an exponential distance dependence of the tunneling is observed for tunneling through various nonbonded contacts. However, the fundamental result from the present study is that at most a modest difference is observed between tunneling mediated by H-bonds and tunneling mediated by van der Waals contacts at typical distances for each type of interaction. These results are considered in relation to the pathways model of Beratan …
Nature's Assembly Line Logic For Natural Products, Christopher T. Walsh, Ryan G. Kruger, David A. Vosburg
Nature's Assembly Line Logic For Natural Products, Christopher T. Walsh, Ryan G. Kruger, David A. Vosburg
All HMC Faculty Publications and Research
Nature fashions a very large number of diverse products (molecular weights ranging from ca. 200 to 2000 daltons) from simple monomeric metabolites used in primary metabolism. These include polyketide scaffolds generated from the simple C₃ malonyl CoA and C₄ methylmalonyl CoA monomers and nonribosomal peptides made from both the 20 proteinogenic amino acids and dozens of nonpoteinogenic amino acids.¹ A large family of terpenoid skeletons are built from the Δ²- and Δ³-alkene isomers of the biological isoprene monomer, isoprenyl-pyrophosphate.²
A Theoretical Investigation Of Charge Transfer In Several Substituted Acridinium Ions, Jason Lappe '00, Robert J. Cave, Marshall D. Newton, I.V. Rostov
A Theoretical Investigation Of Charge Transfer In Several Substituted Acridinium Ions, Jason Lappe '00, Robert J. Cave, Marshall D. Newton, I.V. Rostov
All HMC Faculty Publications and Research
We present calculations for various properties of the ground and excited states of several arylamine-substituted acridinium ion systems that have been studied experimentally. Using ab initio and semiempirical quantum mechanical methods together with the generalized Mulliken−Hush (GMH) model, we examine the excitation energies, dipole moment shifts, and electronic coupling elements for the vertical charge shift (CSh) processes in these systems. We also examine solvent effects on these properties using a dielectric continuum reaction field model. The results are in generally good agreement with available experimental results and indicate that there is strong electronic coupling in these systems over a wide …
Theoretical Investigation Of The Ground And Excited States Of Coumarin 151 And Coumarin 120, Robert J. Cave, Kieron Burke, Edward W. Castner Jr.
Theoretical Investigation Of The Ground And Excited States Of Coumarin 151 And Coumarin 120, Robert J. Cave, Kieron Burke, Edward W. Castner Jr.
All HMC Faculty Publications and Research
We present calculations of various properties of the ground and excited states of Coumarins 151 and 120. These and related coumarins are important in investigating ultrafast solvation processes in liquids and complex solutions as well as being important acceptors in model electron-transfer systems. We calculate the following: (1) the electronic excitation energies to several low-lying singlet states, (2) ground and excited-state dipole moments, (3) solvation effects on excitation energies, and (4) the properties of single Coumarin 151-water complexes. We test our Time-Dependent Density Functional Theory (TDDFT) calculations against CASSCF, CASPT2 (both single and multistate versions), CIS, and ZINDO. Using TDDFT, …
Multistate Effects In Calculations Of The Electronic Coupling Element For Electron Transfer Using The Generalized Mulliken−Hush Method, Michael Rust '01, Jason Lappe '00, Robert J. Cave
Multistate Effects In Calculations Of The Electronic Coupling Element For Electron Transfer Using The Generalized Mulliken−Hush Method, Michael Rust '01, Jason Lappe '00, Robert J. Cave
All HMC Faculty Publications and Research
A simple diagnostic is developed for the purpose of determining when a third state must be considered to calculate the electronic coupling element for a given pair of diabatic states within the context of the generalized Mulliken−Hush approach (Chem. Phys. Lett. 1996, 275, 15−19). The diagnostic is formulated on the basis of Löwdin partitioning theory. In addition, an effective 2-state GMH expression is derived for the coupling as it is modified by the presence of the third state. Results are presented for (i) a model system involving charge transfer from ethylene to methaniminium cation, (ii) a …
Article Are Hydrogen Bonds Unique Among Weak Interactions In Their Ability To Mediate Electronic Coupling?, Emily Cukier '03, Sarah Daniels '02, Eric Vinson '01, Robert J. Cave
Article Are Hydrogen Bonds Unique Among Weak Interactions In Their Ability To Mediate Electronic Coupling?, Emily Cukier '03, Sarah Daniels '02, Eric Vinson '01, Robert J. Cave
All HMC Faculty Publications and Research
Superexchange effects on the electronic coupling element for electron transfer are investigated using water dimers and atomic donors and acceptors. We compare the electronic coupling elements obtained with H-bonded dimers to those obtained for other water dimer geometries at given donor−acceptor and oxygen−oxygen distances. The H-bonded orientation does not yield significantly different coupling elements from non-H-bonded orientations at a given oxygen−oxygen distance. In addition, the distance dependence of the coupling mediated by H-bonds is not significantly different from that for other dimer geometries. It is found that protonation of the intervening waters has a significant effect on coupling elements for …
Time-Dependent Density Functional Theory Investigation Of The Ground And Excited States Of Coumarins 102, 152, 153, And 343, Robert J. Cave, Edward W. Castner Jr.
Time-Dependent Density Functional Theory Investigation Of The Ground And Excited States Of Coumarins 102, 152, 153, And 343, Robert J. Cave, Edward W. Castner Jr.
All HMC Faculty Publications and Research
We present calculations of various properties of the ground and excited electronic states of coumarins 102, 152, 153, and 343. Using density functional theory (DFT) and time-dependent density functional theory (TDDFT), we examine the excitation energies to the S1 and S2 states, the ground and excited-state dipole moments, and the lowest ionization potentials of these coumarins. In the case of C153, we locate two distinct S0 minima due to differing conformations of the julolidyl ring structure and compare properties for the syn and anti conformers. For C343, we examine the possibility of proton transfers in the ground …
Solvent As Electron Donor: Donor/Acceptor Electronic Coupling Is A Dynamical Variable, Edward W. Castner Jr., Darcy Kennedy '00, Robert J. Cave
Solvent As Electron Donor: Donor/Acceptor Electronic Coupling Is A Dynamical Variable, Edward W. Castner Jr., Darcy Kennedy '00, Robert J. Cave
All HMC Faculty Publications and Research
We combine analysis of measurements by femtosecond optical spectroscopy, computer simulations, and the generalized Mulliken−Hush (GMH) theory in the study of electron-transfer reactions and electron donor−acceptor interactions. Our focus is on ultrafast photoinduced electron-transfer reactions from aromatic amine solvent donors to excited-state acceptors. The experimental results from femtosecond dynamical measurements fall into three categories: six coumarin acceptors reductively quenched by N,N-dimethylaniline (DMA), eight electron-donating amine solvents reductively quenching coumarin 152 (7-(dimethylamino)-4-(trifluoromethyl)coumarin), and reductive quenching dynamics of two coumarins by DMA as a function of dilution in the nonreactive solvents toluene and chlorobenzene. Applying a combination of molecular …
On The Vertical And Adiabatic Excitation Energies Of The 21a(G), State Of Trans-1,3-Butadiene, Jason Lappe '00, Robert J. Cave
On The Vertical And Adiabatic Excitation Energies Of The 21a(G), State Of Trans-1,3-Butadiene, Jason Lappe '00, Robert J. Cave
All HMC Faculty Publications and Research
The excitation energy to the 21Ag state of trans-1,3-butadiene is examined using a variety of ab initio electronic structure techniques. While analogous states have been shown to be the lowest singlet excited states for all longer polyenes, for butadiene the position of the 21Ag state relative to the HOMO → LUMO excitation (11Bu) has been difficult to establish theoretically. We employ a variety of methods (CASSCF, CASPT2, MRSDCI, QDVPT) to examine both the vertical and adiabatic excitation energies for this state. At the ground-state geometry, the vertical excitation energies …
A Theoretical Study Of The Electronic Coupling Element For Electron Transfer In Water, Newt E. Miller '99, Matthew C. Wander '97, Robert J. Cave
A Theoretical Study Of The Electronic Coupling Element For Electron Transfer In Water, Newt E. Miller '99, Matthew C. Wander '97, Robert J. Cave
All HMC Faculty Publications and Research
The electronic coupling element for electron transfer between a donor and acceptor in water is examined using simulations combining molecular dynamics and semiempirical quantum mechanics. In the first phase of the simulations a model donor and acceptor are solvated in water, using realistic potentials. Following equilbration, molecular dynamics simulations are performed with the donor, acceptor, and water at approximately 300 K, under periodic boundary conditions. In the second phase of the simulation, the electronic coupling element between the donor and acceptor is calculated for a number of time slices, in the presence of the intervening water molecules (those having a …
An Nmr Investigation Of The Effect Of Hydrogen Bonding On The Rates Of Rotation About The C-N Bonds In Urea And Thiourea, Karl A. Haushalter, Janice Lau, John D. Roberts
An Nmr Investigation Of The Effect Of Hydrogen Bonding On The Rates Of Rotation About The C-N Bonds In Urea And Thiourea, Karl A. Haushalter, Janice Lau, John D. Roberts
All HMC Faculty Publications and Research
The interaction between urea and tetrabutylammonium acetate was investigated in dimethylformamide/ dimethyl sulfoxide solutions using ¹H and 15^N NMR. The chemical-shift behavior of the urea protons is consistent with a urea-acetate hydrogen-bonded complex involving both carboxylate oxygens and the urea hydrogens trans to the carbonyl oxygen with K_assoc = 120 ± 10. Line shape analysis of the temperature-dependent ¹H NMR spectra show that ∆G^‡ for rotation about the C-N bond of urea changes only slightly from 11.0 ± 0.1 to 11.2 ± 0.1 kcal/mol on 1:1 molar addition of tetrabutylammonium acetate to a dilute solution of urea. A parallel investigation …
Theoretical Study Of Solvent Effects On The Electronic Coupling Element In Rigidly Linked Donor-Acceptor Systems, Robert J. Cave, Marshall D. Newton, Krishna Kumar, Matthew B. Zimmt
Theoretical Study Of Solvent Effects On The Electronic Coupling Element In Rigidly Linked Donor-Acceptor Systems, Robert J. Cave, Marshall D. Newton, Krishna Kumar, Matthew B. Zimmt
All HMC Faculty Publications and Research
The recently developed generalized Mulliken-Hush approach for the calculation of the electronic coupling matrix element for electron-transfer processes is applied to two rigidly linked donor-bridge-acceptor systems having dimethoxyanthracene as the donor and a dicarbomethoxycyclobutene unit as the acceptor. The dependence of the electronic coupling matrix element as a function of bridge type is examined with and without solvent molecules present. For clamp-shaped bridge structures solvent can have a dramatic effect on the electronic coupling matrix element. The behavior with variation of solvent is in good agreement with that observed experimentally for these systems.
Resonance Raman Investigation Of The Radical Cation Of 1,3,5-Hexatriene, Tamas Keszthelyi, Robert Wilbrandt, Robert J. Cave, Jenifer L. Johnson
Resonance Raman Investigation Of The Radical Cation Of 1,3,5-Hexatriene, Tamas Keszthelyi, Robert Wilbrandt, Robert J. Cave, Jenifer L. Johnson
All HMC Faculty Publications and Research
The resonance Raman spectrum of the 1,3,5-hexatriene radical cation generated by v-irradiation in a Freon glass is reported. The spectrum is excited at 395 nm in resonance with the second absorption band. Identical spectra are obtained from ionized (E)- and (Z)-1,3,5-hexatriene. The presence of more than one rotamer has to be assumed to account for all the observed resonance Raman bands. The bands are assigned to a mixture of the two rotamers, calculated at lowest energy, the ttt an tct rotamers, on the basis of ab initio ROHF/6-31G calculated harmonic frequencies. The spectrum indicates that …
A Theoretical Investigation Of The Stability Of Hpc, Hannah S. Hong, Robert J. Cave
A Theoretical Investigation Of The Stability Of Hpc, Hannah S. Hong, Robert J. Cave
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Several ab initio methods are applied to the study of two linear isomers of methylidyne phosphine, HCP, and HPC. Single-reference correlation methods ranging from second-order Møller-Plesset theory to coupled cluster singles and doubles theory with noninterative inclusion of connected triple excitations were applied in a variety of basis sets of increasing size. In addition, complete active space self-consistent field wave functions, multireference singles and doubles configuration interaction, and averaged coupled pair functional theory were also applied to HPC. For HPC comparison of the single-reference based results is made with experimental data and previous theory to assess the accuracy …
Optimization In Chemical Kinetics, Arthur T. Benjamin, Gordon J. Hogenson '92
Optimization In Chemical Kinetics, Arthur T. Benjamin, Gordon J. Hogenson '92
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No abstract provided in this article.
A Casscf Study Of Various Rotamers Of The Hexatriene Radical Cation, Robert J. Cave, Jenifer L. Johnson
A Casscf Study Of Various Rotamers Of The Hexatriene Radical Cation, Robert J. Cave, Jenifer L. Johnson
All HMC Faculty Publications and Research
Results are presented from ab initio calculations on the ground and two low-lying excited states of the hexatriene radical cation in a variety of stable conformations of the electronic ground state of the molecule. We have performed Hartree-Fock geometry optimizations using the STO-3G and 6-31g basis sets and have performed vibrational analyses for all stable conformers in the 6-31G basis. In addition, we have performed geometry optimizations in both basis sets using CASSCF wave functions where the five π electrons are correlated. No new geometrical information is obtained at this level of treatment. Excitation energies to the two lowest-lying doublet …
A Theoretical Study Of Models For X2y2 Zintl Ions, Robert J. Cave, Ernest R. Davidson, Philippe Sautet, Enric Canadell, Odile Eisenstein
A Theoretical Study Of Models For X2y2 Zintl Ions, Robert J. Cave, Ernest R. Davidson, Philippe Sautet, Enric Canadell, Odile Eisenstein
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Ab initio and extended Hückel calculations have been used to discuss the bonding scheme in X₂Y₂ neutral and ionic main group clusters. A qualitative analysis suggests that two different electron counts, 20 and 22, are possible for the butterfly structures of these systems. This results from two orbital crossings in the correlation diagram for the tetrahedral (T_d) -> butterfly (C_2v) -> square-planar (D_2h) transformation. Detailed ab initio computations substantiate this analysis and show that the 20-electron butterfly structure becomes increasingly favored over the tetrahedral one in X₂Y₂ clusters when the 2 atoms have increasing electronegativity difference. …