Journal of Molecular Structure-theochem最新文献

{"title":"DFT study of allylic and aliphatic alcohols reactivity: Transesterification and alkylation reactions","authors":"S. Boughdiri ,&nbsp;K. Essalah","doi":"10.1016/j.theochem.2010.07.028","DOIUrl":"10.1016/j.theochem.2010.07.028","url":null,"abstract":"<div><p>The reactions of allylic and aliphatic alcohols with ethyl acetoacetate have been investigated at the DFT/B3LYP level using 6-311G(d) basis set. Analysis results of frontier molecular orbital (FMO) interactions, chemical potential <em>μ</em> and electrophilicity index <em>ω</em> according to Fukui and Pearson respectively, provide a good prediction of experimental results. Alkylation or transesterification reaction is predicted reliably by the calculations.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"958 1","pages":"Pages 21-25"},"PeriodicalIF":0.0,"publicationDate":"2010-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83715075","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":"Study on structures and electronic properties of neutral and charged MgSin- (n = 2–10) clusters with a Gaussian-3 theory","authors":"Hongwei Fan ,&nbsp;Zhiqing Ren ,&nbsp;Jucai Yang ,&nbsp;Dongsheng Hao ,&nbsp;Qiancheng Zhang","doi":"10.1016/j.theochem.2010.07.022","DOIUrl":"10.1016/j.theochem.2010.07.022","url":null,"abstract":"<div><p>The equilibrium geometries, energies, charge transfer, and dipole moments of small MgSi<em>_n</em> (<em>n<!--> </em>=<!--> <!-->2–10) species and their anions have been systematically investigated at the highest level of Gaussian-3 (G3) theory. For neutral MgSi<em>_n</em> clusters, the ground-state structures are found to be “attaching structure” in which the Mg atom is bound to Si<em>_n</em> clusters. The lowest-energy structures for their anions, however, are found to be “substitutional structures”, which are derived from Si<em>_n</em>₊₁ by replacing a Si atom with a Mg atom. The reliable adiabatic electron affinities of MgSi<em>_n</em> have been predicted to be 1.84<!--> <!-->eV for MgSi₂, 1.90<!--> <!-->eV for MgSi₃, 2.17<!--> <!-->eV for MgSi₄, 2.35<!--> <!-->eV for MgSi₅, 2.45<!--> <!-->eV for MgSi₆, 2.18<!--> <!-->eV for MgSi₇, 2.98<!--> <!-->eV for MgSi₈, 3.00<!--> <!-->eV for MgSi₉, and 2.00<!--> <!-->eV for MgSi₁₀. The dissociation energies of Mg atom from the lowest-energy structure of MgSi<em>_n</em> clusters have been evaluated to examine relative stabilities. The charge transfer and dipole moments have also been calculated to further understand the interaction between the Mg atom and the silicon clusters.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"958 1","pages":"Pages 26-32"},"PeriodicalIF":0.0,"publicationDate":"2010-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.022","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76486448","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":"Electronic properties of small Kn (n ⩽ 8) and bimetallic KnCum (n, m ⩽ 4) clusters","authors":"Luis Padilla-Campos ,&nbsp;Emigdio Chávez","doi":"10.1016/j.theochem.2010.07.034","DOIUrl":"10.1016/j.theochem.2010.07.034","url":null,"abstract":"<div><p>The electronic structure and geometry of clusters of the type K<em>_n</em>, <span><math><mrow><msubsup><mrow><mtext>K</mtext></mrow><mrow><mi>n</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></math></span>, K<em>_n</em>Cu<em>_m</em> and <span><math><mrow><msub><mrow><mtext>K</mtext></mrow><mrow><mi>n</mi></mrow></msub><msubsup><mrow><mtext>Cu</mtext></mrow><mrow><mi>m</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></math></span> (<em>n</em>,<!--> <em>m</em> <!-->⩽<!--> <!-->4) were theoretically investigated and compared with similar clusters containing lithium atoms, using density functional methods. The K<em>_n</em>Cu<em>_m</em> bimetallic system is important to understand the promotion effects of the alkali atoms on the copper surface. The inclusion of potassium atoms on a bare copper cluster tends to break the Cu–Cu bond when <em>n</em> <!-->⩾<!--> <em>m</em> favors the formation of polar K–Cu bonds. The geometrical shape of K<em>_n</em> and K<em>_n</em>Cu<em>_m</em> clusters follow the same trend, but the bimetallic clusters are more stable than K<em>_n</em> clusters. However, the global stability of K<em>_n</em> and K<em>_n</em>Cu<em>_m</em> clusters is minor in comparison with corresponding lithium clusters.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"958 1","pages":"Pages 92-100"},"PeriodicalIF":0.0,"publicationDate":"2010-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.034","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79089318","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":"Theoretical observations of the single-electron lithium system H–Be⋯Li–Y (Y = H, OH, F, CCH, CN and NC)","authors":"Li Zhi-Feng ,&nbsp;Zhang Yu-Quan ,&nbsp;Li Hui-Xue ,&nbsp;Zhu Yuan-Cheng ,&nbsp;Yang Sheng","doi":"10.1016/j.theochem.2010.07.025","DOIUrl":"10.1016/j.theochem.2010.07.025","url":null,"abstract":"<div><p>A theoretical calculation of MP2/6-311++G** and MP2/aug-cc-pVDZ was used to predict the single-electron lithium bond system of H–Be⋯Li–Y (Y<!--> <!-->=<!--> <!-->H, OH, F, CCH, CN and NC). The results confirmed H–Be and Li–Y could interact to form the complexes I (HBe⋯Li–H), II (HBe⋯Li–OH), III (HBe⋯Li–F), IV (HBe⋯Li–CCH), V (HBe⋯Li–CN), and VI (HBe⋯Li–NC). The binding energies for these complexes ranged from −22.06 to −27.69<!--> <!-->kJ<!--> <!-->mol⁻¹ at the CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ level. Complex strength was in the order I<!--> <!-->&lt;<!--> <!-->II<!--> <!-->&lt;<!--> <!-->III<!--> <!-->&lt;<!--> <!-->IV<!--> <!-->&lt;<!--> <!-->V<!--> <!-->&lt;<!--> <!-->VI. Analysis of the stretching frequencies showed that complexes I–III were red-shifting single-electron lithium bonds complexes. In contrast, complexes IV–VI were abnormal blue-shifting complexes, and the Li–Y bonds were longer in the complexes than in the corresponding monomers. The characteristics of the complexes were investigated using natural bond orbital (NBO), atoms-in-molecules (AIM) and electrostatic potential map (EPM) theories.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"958 1","pages":"Pages 48-51"},"PeriodicalIF":0.0,"publicationDate":"2010-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.025","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81036423","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 theoretical study of the 2NCO + 2N2H reaction","authors":"Xiang Tiancheng,&nbsp;Zhao Yanru,&nbsp;Xu Jingli,&nbsp;Hu Chaopeng","doi":"10.1016/j.theochem.2010.07.019","DOIUrl":"10.1016/j.theochem.2010.07.019","url":null,"abstract":"<div><p>The singlet and triplet potential surfaces of the ²NCO<!--> <!-->+<!--> ²N₂H reaction have been investigated at the B3LYP/6-311G (d,p) level. The single-point energy calculations are performed at the high-level CCSD (T)/6-311G (d,p) for more accurate energy values. DFT calculations reveal the reaction mechanism to be mainly a barrierless addition of ²NCO to ²N₂H leading to an intermediate ¹im3 (OCN–N₂H) on the singlet potential surface. The adduct ¹im3 goes through an H shift from N₂H to NCO, forming the product of HNCO and N₂. Due to the higher barrier of initial association, the reaction is more difficult on the triplet potential surface.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"958 1","pages":"Pages 10-14"},"PeriodicalIF":0.0,"publicationDate":"2010-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74906289","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":"An ab initio and QTAIM study of hydrogen bonded clusters of nitrosyl hydride with ammonia","authors":"Mohammad Solimannejad,&nbsp;Farshideh Hasanvand Jamshidi,&nbsp;Saeid Amani","doi":"10.1016/j.theochem.2010.07.037","DOIUrl":"10.1016/j.theochem.2010.07.037","url":null,"abstract":"<div><p>Ab initio calculations at MP2/6-311++G(d,p) computational level were used to analyze the interaction between a molecule of the nitrosyl hydride with 1 up to 4 molecules of ammonia. Three minima were found for 1:2 and 1:4 complexes of HNO and NH₃. Four complexes were located as minima on the potential energy surface of 1:3 complexes. Particular attention is given to existence and magnitude of NH⋯N blue-shifting hydrogen bonds. Blue shifts of the N–H stretching frequency upon complex formation in the ranges between 33 and 105<!--> <!-->cm⁻¹ are predicted. Cooperative effect in terms of stabilization energy is calculated for the studied clusters. The cooperative effect is increased with the increasing size of studied clusters. The Quantum Theory Atoms in Molecules (QTAIM) theory was also applied to explain the nature of the complexes.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"958 1","pages":"Pages 116-121"},"PeriodicalIF":0.0,"publicationDate":"2010-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.037","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75096049","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":"Quantum chemical studies on the condensed polynitroazoles","authors":"P. Ravi ,&nbsp;G.M. Gore ,&nbsp;Surya P. Tewari ,&nbsp;A.K. Sikder","doi":"10.1016/j.theochem.2010.07.027","DOIUrl":"10.1016/j.theochem.2010.07.027","url":null,"abstract":"<div><p>Density functional theory (DFT) calculations at the B3LYP/aug-cc-pVDZ level have been performed on the condensed polynitroazoles based on diazole and triazole skeletons. Energy of explosion (≈1.60<!--> <!-->kcal/g), density (≈1.92<!--> <!-->g/cm³), detonation velocity (≈9.30<!--> <!-->km/s), and detonation pressure (≈ 39<!--> <!-->GPa) of model molecules are found to be promising compared to the well known explosives 1,3,5-trinitro-1,3,5-triazinane (RDX), octahydro-1,3,5,7-tetranitro-l,3,5,7-tetraazocane (HMX), and 4,4′,5,5′-tetranitro-2,2′-bi-1<em>H</em>-imidazole (TNBI). Presumably, the relative positions of nitro groups and the nature of azole ring determines the geometry, stability, sensitivity, density and thus detonation performance.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"958 1","pages":"Pages 52-58"},"PeriodicalIF":0.0,"publicationDate":"2010-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.027","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84967825","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":"Theoretical studies on the proton affinities of four different series of nano-size diamines and designing strong superbases based on fullerene(C60) molecule","authors":"Mehdi Bayat,&nbsp;Sadegh Salehzadeh","doi":"10.1016/j.theochem.2010.07.015","DOIUrl":"10.1016/j.theochem.2010.07.015","url":null,"abstract":"<div><p>Density functional theory (B3LYP) calculation is used to determine the gas-phase proton affinities of four series of nano-size diamines (1–2.3<!--> <!-->nm) including –(CH₂)<em>_n</em>–C₆₀–(CH₂)<em>_n</em>–, –(C₆H₄)<em>_n</em>–, –(CH<img>CH)<em>_n</em>–, and –(CH₂)<em>_n</em>– spacers, where the maximum value of <em>n</em> is 5, 5, 9 and 15, respectively. The results showed that, in the case of diamines with two former spacers the first proton affinity, <em>PA</em>₁, decreases by increasing the value of <em>n</em>, while in the case of two latter diamines it increases by increasing the value of <em>n</em>. However, the second proton affinity, <em>PA</em>₂, and proton overallaffinity, <em>PA_ov</em>, of all above molecules, as expected, increases with increasing the value of <em>n</em>. Among all above compounds the greatest amounts of the <em>PA</em>₁ and <em>PA</em>₂ were calculated for H₂NCH₂–C₆₀–CH₂NH₂ and H₂N–(CH₂)₁₅–NH₂ molecules, respectively. It seems that the C₆₀ molecule has an increasing effect on <em>PA</em>₁ of diamines, while a saturated long aliphatic chain which separates well the positively charged nitrogen atoms has an increasing effect on <em>PA</em>₂ of diamines. The above results has led us to design new nano-size superbases with –N(CH₃)₂ or –N<img>C{N(CH₃)₂}₂ basic groups on fullerene molecule. The amounts of <em>PA</em>₁, <em>PA</em>₂ and <em>PA_ov</em>, for one of these superbases are 1126.3, 786.6 and 1912.9<!--> <!-->kJ<!--> <!-->mol⁻¹, respectively, indicating that it is one of the strongest superbases known so far.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"957 1","pages":"Pages 120-125"},"PeriodicalIF":0.0,"publicationDate":"2010-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78720121","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":"Adsorption of NO and N2O on Cu-BEA zeolite","authors":"Yuli Wang,&nbsp;Zhigang Lei,&nbsp;Runduo Zhang,&nbsp;Biaohua Chen","doi":"10.1016/j.theochem.2010.07.004","DOIUrl":"10.1016/j.theochem.2010.07.004","url":null,"abstract":"<div><p>Density function theory (DFT) has been applied to investigate the interactions between NO and N₂O with Cu⁺ species in a beta zeolite (BEA) at sites T1 and T9. The geometries for Cu-BEA represented as 10T cluster, and complexes of NO and N₂O adsorptions on them in <em>η</em>¹-O and <em>η</em>¹-N modes have been completely optimized. The calculated results showed that NOx could be adsorbed on Cu⁺ species in two modes, and N–O bond distances of NOx increase after adsorption. The adsorption energies of NO and N₂O molecules in <em>η</em>¹-N mode on Cu-BEA are larger than in <em>η</em>¹-O mode, and the interactions between N₂O or NO and Cu-BEA at site T9 are stronger than at T1 site.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"957 1","pages":"Pages 41-46"},"PeriodicalIF":0.0,"publicationDate":"2010-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80938510","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":"The enthalpies of formation of brominated benzenes and phenols: A theoretical prediction","authors":"Liming Wang,&nbsp;Yanfen Liu","doi":"10.1016/j.theochem.2010.07.009","DOIUrl":"10.1016/j.theochem.2010.07.009","url":null,"abstract":"<div><p>The enthalpies of formation of brominated benzenes and phenols were predicted using Gaussian-4 (G4), G3X, and G3XMP2 model chemistries and a few popular density functional methods, coupled with homodesmic reactions <span>(HR1)</span>, <span>(HR2)</span> in which C₆H₆, C₆H₅Br, and C₆H₅OH are used as reference compounds. The results from G4, G3X, and G3XMP2 agree closely within 2<!--> <!-->kJ/mol for all brominated benzenes and phenols; while the results from density functional methods are systematically higher than the G4 ones. The predicted enthalpies of formation for 2- and 4-bromophenols are in close agreement with the recent experimental measurements. Three reactions <span>(R1)</span>, <span>(R2)</span>, <span>(R3)</span> were also used to derive <span><math><mrow><msub><mrow><mi>Δ</mi></mrow><mrow><mtext>f</mtext></mrow></msub><msubsup><mrow><mi>H</mi></mrow><mrow><mn>298</mn><mtext>K</mtext></mrow><mrow><mi>°</mi></mrow></msubsup></mrow></math></span>(g, C₆H₅Br)<!--> <!-->=<!--> <!-->98.7<!--> <!-->±<!--> <!-->1.0<!--> <!-->kJ/mol by using CH₄, CH₃Br, CH₂Br₂, CH₂CHBr, and C₆H₆ as reference compounds at G4 and G3X levels. The value is significantly lower than the only experimental value of 105.4<!--> <!-->kJ/mol given by Cox and Pilcher in 1970, and a re-determination is called.</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"957 1","pages":"Pages 72-76"},"PeriodicalIF":0.0,"publicationDate":"2010-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.07.009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82932378","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}