Jingling Shao , Chunyan He , Rongwei Shi , Cheng Wang , Xiaolei Zhu , Xiaohua Lu
{"title":"Exploration of structures and stability of planar CnB3 (n = 1–8)","authors":"Jingling Shao , Chunyan He , Rongwei Shi , Cheng Wang , Xiaolei Zhu , Xiaohua Lu","doi":"10.1016/j.theochem.2010.08.036","DOIUrl":null,"url":null,"abstract":"<div><p>The structures and relative stabilities of C<em><sub>n</sub></em>B<sub>3</sub> (<em>n</em> <!-->=<!--> <!-->1–8) clusters are explored and analyzed at the CCSD(T)/6-311+G(d)//B3LYP/6-311+G(d) level. For low-lying isomers of C<em><sub>n</sub></em>B<sub>3</sub> (<em>n</em> <!-->=<!--> <!-->1–8), cyclic structures are more favorable in energy than branch as well as linear structures, and rings with exocyclic chains. For most isomers of C<em><sub>n</sub></em>B<sub>3</sub> (<em>n</em> <!-->=<!--> <!-->1–8), the structures with doublet states are lower in energy than the ones with quartet states. The lowest-energy isomers of C<em><sub>n</sub></em>B<sub>3</sub> are all cyclic structures. The lowest-energy structures of C<em><sub>n</sub></em>B<sub>3</sub> (<em>n</em> <!-->=<!--> <!-->1–3) appear to be similar to those of pure boron clusters which have polycylic structures, while the lowest-energy structures of C<em><sub>n</sub></em>B<sub>3</sub> (<em>n</em> <!-->=<!--> <!-->4–8) tend to be analogous to the corresponding geometries of pure carbon, C<em><sub>n</sub></em>B, and C<em><sub>n</sub></em>B<sub>2</sub> clusters which possess single-ring structures. The most stable structures of planar C<em><sub>n</sub></em>B<sub>3</sub> (<em>n</em> <!-->=<!--> <!-->3–8) clusters can be derived from combining a B–C–B–C–C–B building unit and a carbon chain. Some physical properties, such as the binding energy per atom, incremental binding energy, and second order energy difference suggest that for C<em><sub>n</sub></em>B<sub>3</sub> clusters, odd-<em>n</em> clusters are more stable than even-<em>n</em> clusters. Results from NBO and molecular orbital analysis illustrate that the formation of the delocalized π MOs, the σ-radial and σ-tangential MOs are favorable to the stabilization of structures for lowest-energy isomers. It is interesting to find from the valence molecular orbital and NBO analyses that for the most stable isomers of C<em><sub>n</sub></em>B<sub>3</sub> (<em>n</em> <!-->=<!--> <!-->1–8), the numbers of π electrons for C<em><sub>n</sub></em>B<sub>3</sub> (<em>n</em> <!-->=<!--> <!-->1–8) is (<em>n</em> <!-->+<!--> <!-->1) with an exception of C<sub>4</sub>B<sub>3</sub> (6 π electrons), suggesting that CB<sub>3</sub>, C<sub>4</sub>B<sub>3</sub> and C<sub>5</sub>B<sub>3</sub> may have aromaticity, which is consistent with the results of the nucleus independent chemical shifts (NICS).</p></div>","PeriodicalId":16419,"journal":{"name":"Journal of Molecular Structure-theochem","volume":"961 1","pages":"Pages 17-28"},"PeriodicalIF":0.0000,"publicationDate":"2010-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.theochem.2010.08.036","citationCount":"11","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Molecular Structure-theochem","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0166128010005701","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 11
Abstract
The structures and relative stabilities of CnB3 (n = 1–8) clusters are explored and analyzed at the CCSD(T)/6-311+G(d)//B3LYP/6-311+G(d) level. For low-lying isomers of CnB3 (n = 1–8), cyclic structures are more favorable in energy than branch as well as linear structures, and rings with exocyclic chains. For most isomers of CnB3 (n = 1–8), the structures with doublet states are lower in energy than the ones with quartet states. The lowest-energy isomers of CnB3 are all cyclic structures. The lowest-energy structures of CnB3 (n = 1–3) appear to be similar to those of pure boron clusters which have polycylic structures, while the lowest-energy structures of CnB3 (n = 4–8) tend to be analogous to the corresponding geometries of pure carbon, CnB, and CnB2 clusters which possess single-ring structures. The most stable structures of planar CnB3 (n = 3–8) clusters can be derived from combining a B–C–B–C–C–B building unit and a carbon chain. Some physical properties, such as the binding energy per atom, incremental binding energy, and second order energy difference suggest that for CnB3 clusters, odd-n clusters are more stable than even-n clusters. Results from NBO and molecular orbital analysis illustrate that the formation of the delocalized π MOs, the σ-radial and σ-tangential MOs are favorable to the stabilization of structures for lowest-energy isomers. It is interesting to find from the valence molecular orbital and NBO analyses that for the most stable isomers of CnB3 (n = 1–8), the numbers of π electrons for CnB3 (n = 1–8) is (n + 1) with an exception of C4B3 (6 π electrons), suggesting that CB3, C4B3 and C5B3 may have aromaticity, which is consistent with the results of the nucleus independent chemical shifts (NICS).