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Full-Text Articles in Chemistry

Iron(Ii) Complexes Of Di­Methyl­Tri­Aza­Cyclo­Phane, Wei-Tsung Less, Matthias Zeller, David Upp, Yuliya Politanska, Doug Steinman, Talal Al-Assil, Daniel P. Becker Ph.D. Mar 2019

Iron(Ii) Complexes Of Di­Methyl­Tri­Aza­Cyclo­Phane, Wei-Tsung Less, Matthias Zeller, David Upp, Yuliya Politanska, Doug Steinman, Talal Al-Assil, Daniel P. Becker Ph.D.

Wei-Tsung Lee

Treatment of the ortho-tri­aza­cyclo­phane 1,4-di­methyl­tribenzo[b,e,h][1,4,7]tri­aza­cyclo­nona-2,5,8-triene [(C6H5)3(NH)(NCH3)2, L1] with Fe[N(SiMe3)2]2 yields the dimeric iron(II) complex bis­(μ-1,4-di­methyl­tribenzo[b,e,h][1,4,7]tri­aza­cyclo­nona-2,5,8-trien-7-ido)bis­[(μ-1,4-di­methyl­tribenzo[b,e,h][1,4,7]tri­aza­cyclo­nona-2,5,8-trien-7-ido)iron(II)], [Fe(C20H18N3)4] or Fe2(L1)4 (9). Dissolution of 9 in tetra­hydro­furan (THF) results in solvation by two THF ligands and the formation of a simpler monoiron complex, namely bis­(μ-1,4-di­methyl­tribenzo[b,e,h][1,4,7]tri­aza­cyclo­nona-2,5,8-trien-7-ido-κN7 …


Combinatorial Computational Chemistry Approach To The Design Of DenoX Catalysts, K. Yajima, Y. Ueda, H. Tsuruya, T. Kanougi, Y. Oumi, Salai Ammal, S. Takami, M. Kubo, A. Miyamoto May 2015

Combinatorial Computational Chemistry Approach To The Design Of DenoX Catalysts, K. Yajima, Y. Ueda, H. Tsuruya, T. Kanougi, Y. Oumi, Salai Ammal, S. Takami, M. Kubo, A. Miyamoto

Salai C. Ammal

No abstract provided.


Importance And Reliability Of Small Basis Set Ccsd(T) Corrections To Mp2 Binding And Relative Energies Of Water Clusters, Berhane Temelso, Carla Renner, George Shields Mar 2015

Importance And Reliability Of Small Basis Set Ccsd(T) Corrections To Mp2 Binding And Relative Energies Of Water Clusters, Berhane Temelso, Carla Renner, George Shields

Berhane Temelso

MP2 describes hydrogen-bonded systems well, yet a higher-order electron correlation correction in the form of a CCSD(T) calculation is usually necessary to achieve benchmark quality energies. We evaluated the importance and reliability of small basis set CCSD(T) corrections to MP2(δCCSD(T)) both on the binding (ΔE) and relative (ΔΔE) MP2 energies for a large number of systems including four water dimer stationary points and 57 other clusters up to undecamers, (H2O)11. By comparing the MP2 energies with CCSD(T) and the explicitly correlated MP2-F12 energies with variants of CCSD(T)-F12 using different basis sets, we were able to establish that the correction to …


Computational Estimation Of Pka Values, Paul Seybold, George Shields Dec 2014

Computational Estimation Of Pka Values, Paul Seybold, George Shields

Berhane Temelso

The pKa of a compound is one of its most important properties as it defines the specific molecular forms that will prevail under different pH conditions. Accordingly, accurate means for computational estimation of this property are of particular interest. Two main techniques for this purpose have emerged: (1) a first principles approach that relies on basic physical concepts and requires high computational resources, but is independent of experimental input and (2) a linear free energy or quantitative structure–activity relationship (QSAR) approach that combines molecular structural and energetic descriptors with available experimental pKa data to reduce computational demand and yield good …


Structure And Thermodynamics Of H3o+(H2o)8 Clusters: A Combined Molecular Dynamics And Quantum Mechanics Approach, Berhane Temelso, Thorsten Koddermann, Karl K. Kirschner, Katurah L. Klein, George C. Shields Sep 2014

Structure And Thermodynamics Of H3o+(H2o)8 Clusters: A Combined Molecular Dynamics And Quantum Mechanics Approach, Berhane Temelso, Thorsten Koddermann, Karl K. Kirschner, Katurah L. Klein, George C. Shields

Berhane Temelso

We have studied the structure and stability of (H3O+)(H2O)8 clusters using a combination of molecular dynamics sampling and high-level ab initio calculations. 20 distinct oxygen frameworks are found within 2 kcal/mol of the electronic or standard Gibbs free energy minimum. The impact of quantum zero-point vibrational corrections on the relative stability of these isomers is quite significant. The box-like isomers are favored in terms of electronic energy, but with the inclusion of zero-point vibrational corrections and entropic effects tree-like isomers are favored at higher temperatures. Under conditions from 0 to 298.15 K, the global minimum is predicted to be a …


Computational Study Of The Hydration Of Sulfuric Acid Dimers: Implications For Acid Dissociation And Aerosol Formation, Berhane Temelso, Thuong Ngoc Phan, George C. Shields Sep 2014

Computational Study Of The Hydration Of Sulfuric Acid Dimers: Implications For Acid Dissociation And Aerosol Formation, Berhane Temelso, Thuong Ngoc Phan, George C. Shields

Berhane Temelso

We have investigated the thermodynamics of sulfuric acid dimer hydration using ab initio quantum mechanical methods. For (H2SO4)2(H2O)n where n = 0−6, we employed high-level ab initio calculations to locate the most stable minima for each cluster size. The results presented herein yield a detailed understanding of the first deprotonation of sulfuric acid as a function of temperature for a system consisting of two sulfuric acid molecules and up to six waters. At 0 K, a cluster of two sulfuric acid molecules and one water remains undissociated. Addition of a second water begins the deprotonation of the first sulfuric acid …


Broadband Fourier Transform Rotational Spectroscopy For Structure Determination: The Water Heptamer, Cristóbal Pérez, Simon Lobsiger, Nathan A. Seifert, Daniel P. Zaleski, Berhane Temelso, George C. Shields, Zbigniew Kisiel, Brooks H. Pate Sep 2014

Broadband Fourier Transform Rotational Spectroscopy For Structure Determination: The Water Heptamer, Cristóbal Pérez, Simon Lobsiger, Nathan A. Seifert, Daniel P. Zaleski, Berhane Temelso, George C. Shields, Zbigniew Kisiel, Brooks H. Pate

Berhane Temelso

Over the recent years chirped-pulse, Fourier-transform microwave (CP-FTMW) spectrometers have chan- ged the scope of rotational spectroscopy. The broad frequency and large dynamic range make possible structural determinations in molecular systems of increasingly larger size from measurements of heavy atom (13C, 15N, 18O) isotopes recorded in natural abundance in the same spectrum as that of the parent isotopic species. The design of a broadband spectrometer operating in the 2–8 GHz frequency range with further improvements in sensitivity is presented. The current CP-FTMW spectrometer performance is benchmarked in the analyses of the rotational spectrum of the water …