Journal of Molecular Structure-theochem最新文献

{"title":"The electronic properties of a homoleptic bisphosphine Cu(I) complex: A joint theoretical and experimental insight","authors":"Gianluca Accorsi ,&nbsp;Nicola Armaroli ,&nbsp;Béatrice Delavaux-Nicot ,&nbsp;Adrien Kaeser ,&nbsp;Michel Holler ,&nbsp;Jean-François Nierengarten ,&nbsp;Alessandra Degli Esposti","doi":"10.1016/j.theochem.2010.09.012","DOIUrl":"10.1016/j.theochem.2010.09.012","url":null,"abstract":"<div><p>The origin of the optical properties of the firstly reported stable luminescent <span><math><mrow><mo>[</mo><mtext>Cu</mtext><mo>(</mo><mtext>PP</mtext><msub><mrow><mo>)</mo></mrow><mrow><mn>2</mn></mrow></msub><msup><mrow><mo>]</mo></mrow><mrow><mo>+</mo></mrow></msup></mrow></math></span> complex <span><math><mrow><mo>[</mo><mtext>Cu</mtext><mo>(</mo><mtext>dppb</mtext><msub><mrow><mo>)</mo></mrow><mrow><mn>2</mn></mrow></msub><msup><mrow><mo>]</mo></mrow><mrow><mo>+</mo></mrow></msup><mo>[</mo><mtext>dppb</mtext><mo>=</mo><mn>1</mn><mtext>,</mtext><mn>2</mn><mo>-</mo><mtext>bis</mtext><mo>(</mo><mtext>diphenylphosphino</mtext><mo>)</mo><mtext>benzene</mtext><mo>]</mo></mrow></math></span> is investigated using the exchange–correlation functional PBE0. The choice of the basis set used is discussed and a comparison with the results obtained by other functionals is performed. The role played by the bisphosphine ligands within the complex is elucidated by considering the electronic properties of the ligand alone to evidence how both the geometrical changes and the electronic interactions, induced by the inclusion of the metal cation, affect the electronic behavior of the whole system. The NBO analysis shows how the aryl groups of the ligands act as a reservoir of electrons within the complex. The electronic excitations of both the complex and of the ligand, calculated by including the solvation effects, allow to assign the lowest energy absorption broad band, recorded in CH₂Cl₂ solution. The peculiar contribution of the phosphorus atoms to the description of the high occupied MOs and the participation of the copper cation to the description of the lowest singlet excited state, is pointed out. The origin of the observed phosphorescence of the complex is attributed to a triplet state, whose SOMO is characterized by the contributions of the valence 4<em>s</em> and of the Rydberg 5<em>s</em> AOs of the metal cation, along with the lone pair orbitals of the P atoms.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 7-14"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.09.012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73231255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comparative computational study of novel X–Be–N2–Li and X–Mg–N2–Li species (X = F, Cl, Br)","authors":"Sean A.C. McDowell,&nbsp;Katrina P. Price","doi":"10.1016/j.theochem.2010.09.019","DOIUrl":"10.1016/j.theochem.2010.09.019","url":null,"abstract":"<div><p>A computational study predicts a number of unusual Be- and Mg-containing compounds with general formula X–M–N₂–Li (X<!--> <!-->=<!--> <!-->F, Cl, Br; M<!--> <!-->=<!--> <!-->Be, Mg). Generally, the X–Be–N₂–Li species were found to be energetically stable with respect to the LiX<!--> <!-->+<!--> <!-->Be<!--> <!-->+<!--> <!-->N₂ fragments and with respect to the LiBeX<!--> <!-->+<!--> <!-->N₂ fragments, whereas the Mg-containing species by comparison were found to be unstable. Harmonic vibrational frequencies and various bonding parameters were also computed and found useful in rationalizing the relative stabilities and trends (for varying X) of these unusual compounds. The high stability of X–Be–N₂–Li is thought to be due mainly to strong electrostatic interactions between the constituent atoms and especially the Be atom in its +2 valence state.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 85-89"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.09.019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76749058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrogen desorption mechanism of a Li–N–H hydrogen storage system","authors":"Min Hee Park ,&nbsp;Hyungjun Kim ,&nbsp;Jae Jung Urm ,&nbsp;Jun Ho Lee ,&nbsp;Young-Kyu Han ,&nbsp;Yoon Sup Lee","doi":"10.1016/j.theochem.2010.09.016","DOIUrl":"10.1016/j.theochem.2010.09.016","url":null,"abstract":"<div><p>Alkali metal amides may exist in solution, the solid phase, and even the gas phase. Based on a theoretical model of a Li₃N system which adsorbs and desorbs two hydrogen molecules, we examine the possible pathways of the <span><math><mrow><msub><mrow><mtext>Li</mtext></mrow><mrow><mn>3</mn></mrow></msub><mtext>N</mtext><mo>+</mo><mn>2</mn><msub><mrow><mtext>H</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>↔</mo><msub><mrow><mtext>LiNH</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>+</mo><mn>2</mn><mtext>LiH</mtext></mrow></math></span> reversible reaction. The dehydrogenation process can be separated into two-step reactions, <span><math><mrow><msub><mrow><mtext>Li</mtext></mrow><mrow><mn>2</mn></mrow></msub><mtext>NH</mtext><mo>+</mo><mtext>LiH</mtext><mo>→</mo><msub><mrow><mtext>Li</mtext></mrow><mrow><mn>3</mn></mrow></msub><mtext>N</mtext><mo>+</mo><msub><mrow><mtext>H</mtext></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span> (−9.5<!--> <!-->kcal/mol exothermic) and <span><math><mrow><msub><mrow><mtext>LiNH</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>+</mo><mtext>LiH</mtext><mo>→</mo><msub><mrow><mtext>Li</mtext></mrow><mrow><mn>2</mn></mrow></msub><mtext>NH</mtext><mo>+</mo><msub><mrow><mtext>H</mtext></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span> (+0.7<!--> <!-->kcal/mol endothermic). Along the reaction pathway, two intermediates and a transition state for each reaction were found in our <em>ab initio</em> molecular orbital calculations at the MP2 and CCSD(T) levels of theory. A total of two H₂ molecules can be stored and released at normal temperature and pressure if there are means to substantially raise the energy of the two stable intermediates. Reaction energy profiles from our calculations support the much higher temperature of the first step reaction in experiment.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 68-71"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.09.016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80428835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intramolecular dihydrogen bond: A new perspective in Lewis acid catalyzed nucleophilic epoxide ring opening reaction","authors":"Vaibhav A. Dixit,&nbsp;Prakash C. Rathi,&nbsp;Prasad V. Bharatam","doi":"10.1016/j.theochem.2010.09.020","DOIUrl":"10.1016/j.theochem.2010.09.020","url":null,"abstract":"<div><p>Nucleophilic epoxide ring opening reactions can be effectively carried out with BF₃ but not with BH₃. This has been traced to the formation of an intermediate with an intramolecular dihydrogen bond which prefers to yield a species with frustrated Lewis acid–base pair after liberating H₂ molecule in the BH₃ catalyzed system. Quantum chemical analysis indicates that the H₂ liberation is more favorable by 37.8<!--> <!-->kcal/mol in comparison to the desired aminoalcohol formation.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 97-100"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.09.020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86347298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive ab initio study on the conformations of L-Threonine and L-allo-Threonine and related species in gas phase","authors":"Xuee Xu ,&nbsp;Zijing Lin","doi":"10.1016/j.theochem.2010.09.010","DOIUrl":"10.1016/j.theochem.2010.09.010","url":null,"abstract":"<div><p>Systematic conformational searches have been performed for various species of L-Threonine (L-Thr) and L-allo-Threonine (L-allo-Thr) in gas phase. The trial structures were generated by allowing for all combinations of internal single-bond rotamers. The trial structures were optimized at the HF/3-21G(d) level and then subjected to further optimization at the B3LYP/6-311++G(d,<!--> <!-->p) level. A total of 74 canonical neutral, 12 protonated, 22 deprotonated and 4 secondary deprotonated conformers are found for the L-Thr species, while 75 canonical neutral, 14 protonated, 22 deprotonated, and 6 secondary deprotonated conformers are found for the L-allo-Thr species. However, no stable zwitterionic structures of isolated threonine may exist. The conformational energies are determined by the MP2/6-311+G(2df,<!--> <!-->p) calculations. The intramolecular hydrogen bonds were characterized. The equilibrium conformer distributions at different temperatures are shown. The proton affinities, gas phase basicities, proton dissociation energies and gas phase acidities are determined and compared with the experiments. The conformations of threonine hydrated with one water molecule were also systematically searched. The zwitterionic structures may be stabilized by one water molecule, but their energies are relatively high. The infrared spectra of the most stable structures of all species are presented.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 23-32"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.09.010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79977220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On quasi-tranferable molecular fragments. Part IV. Bond energies and bond dissociation: Novel approaches and comparisons with classical results","authors":"Sándor Fliszár ,&nbsp;Édouard C. Vauthier","doi":"10.1016/j.theochem.2010.09.008","DOIUrl":"10.1016/j.theochem.2010.09.008","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Results given by the new formula for the standard perfect-gas enthalpy of formation, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Δ&lt;/mi&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mtext&gt;f&lt;/mtext&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∘&lt;/mo&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mo&gt;∑&lt;/mo&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mtext&gt;K&lt;/mtext&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mtext&gt;K&lt;/mtext&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mtext&gt;ZPE&lt;/mtext&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;-&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;-&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mo&gt;∑&lt;/mo&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ε&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;kl&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;-&lt;/mo&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mtext&gt;CNE&lt;/mtext&gt;&lt;mo&gt;-&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;E&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mtext&gt;nb&lt;/mtext&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, are compared with experiment. &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mtext&gt;K&lt;/mtext&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mtext&gt;,&lt;/mtext&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mtext&gt;L&lt;/mtext&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mtext&gt;,&lt;/mtext&gt;&lt;mo&gt;…&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; are fixed parameters of chemical groups K, L, etc. and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ε&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;kl&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is the intrinsic energy of the link between K and L. &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Z&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mtext&gt;ZPE&lt;/mtext&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;-&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is the familiar sum of zero-point&lt;!--&gt; &lt;!--&gt;+&lt;!--&gt; &lt;!--&gt;heat-content energies and CNE accounts for the fact that the fragments K, L, etc. are not individually electroneutral in their host molecule. &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;E&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mtext&gt;nb&lt;/mtext&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; stands for nonbonded interactions between the fragments. The reduction of the 3-fragment formula applicable to molecules written K-[CH(X)]-L to get its equivalent for the 2-fragment form [CHK(X)]-L reveals a most useful relationship between the functions &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;[CH(X)] and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;[&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mtext&gt;CH&lt;/mtext&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;(X)]: the latter is usually easy to obtain, but it is &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;[CH(X)] that is actually required in the 3-fragment problem K-[CH(X)]-L. Fragments of this form, already known for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mtext&gt;X&lt;/mtext&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mtext&gt;CH&lt;/mtext&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, were successfully tested for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mtext&gt;X&lt;/mtext&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mtext&gt;C&lt;/mtext&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mtext&gt;H&lt;/mtext&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mtext&gt;,&lt;/mtext&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mo&gt;-&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mtext&gt;C&lt;/mtext&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mtext&gt;H&lt;/mtext&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mtext&gt;,&lt;/mtext&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mtext&gt;C&lt;/mtext&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;/mrow&gt;&lt;/","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 38-44"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.09.008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75722848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Why Lewis acids accelerate the thermal Curtius rearrangement of benzoyl azide into phenyl isocyanate","authors":"Maxim V. Zabalov,&nbsp;Roald P. Tiger","doi":"10.1016/j.theochem.2010.09.009","DOIUrl":"10.1016/j.theochem.2010.09.009","url":null,"abstract":"<div><p>The thermal Curtius rearrangement of benzoyl azide in the presence of Lewis acids has been studied by DFT (PBE/TZ2P) method. The complexation of Lewis acids (BF₃, AlCl₃, SbCl₅) with benzoyl azide leads to the formation of 1:1 and 1:2 stable complexes with interaction of catalysts with O and N atoms of carbonyl azide group. The potential energy surfaces of the catalytic rearrangement have been calculated for each complex and the relation between the complexes and the transition states on potential energy surface have been established by IRC calculation. The energy barriers for catalytic reactions are significantly lower in the most cases in comparison with an uncatalyzed reaction. The activation energy is decreasing in the range of Lewis acids AlCl₃ <!-->&gt;<!--> <!-->SbCl₅ <!-->&gt;<!--> <!-->BF₃ and it correlates with the decreasing of Lewis acids strength. The Mulliken bond population analysis has been done for three compounds RCON₃ (R<!--> <!-->=<!--> <!-->H, Me, Ph) and for their complexes, and for all corresponding transition states using the B3LYP/6-311G∗ approximation. The interaction of Lewis acids with carbonyl azide group causes the decreasing of N1<img>N2 bond strength and it helps the thermal Curtius rearrangement to proceed.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 15-22"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.09.009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75157282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural, electronic, and optical properties of novel indolocarbazole-based conjugated derivatives","authors":"Michel Belletête ,&nbsp;Pierre-Luc T. Boudreault ,&nbsp;Mario Leclerc ,&nbsp;Gilles Durocher","doi":"10.1016/j.theochem.2010.09.011","DOIUrl":"10.1016/j.theochem.2010.09.011","url":null,"abstract":"<div><p>A study of the structure, electronic, and optical properties of new indolo[3,2-<em>b</em>]carbazoles is reported. Geometry optimizations of the ground state of the derivatives were carried out using the density functional theory (DFT) with the B3LYP functional and the 6-31G∗ basis set. Molecules disubstituted with phenyl or thiophene units at molecular ends were found nonplanar in their electronic ground states (S₀), whereas indolocarbazoles having phenylenevinylenes at molecular ends are nearly planar. The electronic excitation transitions of the indolocarbazoles were investigated using the time-dependent (TD) DFT method performed on the ground state optimized geometries. For all the derivatives, excitation to the S₁ state corresponds mainly to LUMO<!--> <!-->←<!--> <!-->HOMO transition, whereas the second electronic transition mainly originates from the LUMO<!--> <!-->←<!--> <!-->HOMO<!--> <!-->−<!--> <!-->1 excitation. The excitation energies are found in fair agreement with the absorption energies of the indolocarbazoles. The optimization (relaxation) of the first singlet excited electronic state (S₁) has been done using the restricted configuration interaction (singles) (RCIS/6-31G∗) approach. The electronically excited geometries favor a more quinoidic type structure. Emission energies have been obtained from TDDFT calculations performed on the S₁ optimized geometries and are in fair agreement with experimental data obtained from fluorescence spectra. The change from phenyl to thiophene rings as well as the incorporation of vinyl units between the phenyl and the indocarbazole moieties induce a significant decrease in the excitation and emission energies.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 33-37"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.09.011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76046898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Density functional theory study of the hydrogen chemisorption of single-walled carbon nanotubes with carbon ad-dimer defect","authors":"Donglai Wang,&nbsp;Caihong Zhao,&nbsp;Guang Xin,&nbsp;Dongyan Hou","doi":"10.1016/j.theochem.2010.09.015","DOIUrl":"10.1016/j.theochem.2010.09.015","url":null,"abstract":"<div><p>The structural and electronic properties of hydrogenated armchair and zigzag SWCNTs with carbon ad-dimer (CD) defect were investigated by means of the B3LYP hybrid density functional method using 6-31G∗ basis set. It is found that the chemisorptions of two hydrogen atoms inside and outside the CD defective SWCNTs are exothermic processes. Exohedral nanotube adsorption is energetically more favorable than endohedral adsorption. These results are in agreement with hydrogen on pristine nanotubes. The positional preference for the chemisorption of two hydrogen atoms is the same for the CD defective armchair and zigzag nanotubes. However, the reaction energy of two hydrogen atoms on the exterior sidewalls of CD defective SWCNTs is almost independent of the tube diameter. This is different from the results reported on pristine nanotubes. The calculated energy gaps indicate that the hydrogen-chemisorbed CD defective armchair tubes are always wide energy gap structures, while the hydrogen-chemisorbed CD defective zigzag tubes have significantly lower gaps. The HOMO–LUMO gap and reaction energy for the chemisorption of more hydrogen atoms on the exterior sidewalls of CD defective armchair SWCNTs were also explored.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 62-67"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.09.015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81713346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Density functional theory study of relevant properties of lanthanum species and 1-butene activation over lanthanum modified zeolite","authors":"Shujun Jiang ,&nbsp;Shiping Huang ,&nbsp;Lijia Qin ,&nbsp;Weixia Tu ,&nbsp;Jiqin Zhu ,&nbsp;Huiping Tian ,&nbsp;Peng Wang","doi":"10.1016/j.theochem.2010.08.031","DOIUrl":"10.1016/j.theochem.2010.08.031","url":null,"abstract":"<div><p>The structure and acidity of lanthanum species of modified zeolites have been investigated by using the density functional theory. The mechanism of 1-butene activation has also been studied with the effect of the channel wall in the zeolites. Lanthanum sites are computed to be less acidic than the Brønsted (Al–OH–Si) ones. The lanthanum species are very stable in modified zeolites even at the temperature of 650<!--> <!-->K. The average frequency of the O–H stretching in lanthanum species is 3758<!--> <!-->cm⁻¹, while the frequency of the O–H stretching in H-ZSM-5 is 3646<!--> <!-->cm⁻¹. The reaction path of more stable carbenium formation is considered. The activation barrier is 42.93<!--> <!-->kcal/mol. There is no π-complex presented in the adsorption states and the reaction mechanism is different from the catalytic cracking reactions on H-ZSM-5 zeolites.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"962 1","pages":"Pages 1-6"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.08.031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84560047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}