平面四配位和五配位的B6S5团簇

Planar Tetracoordinate Boron and Pentacoordinate Boron in B6S5 Clusters

采用B3LYP/def2-TZVP优化和在耦合簇方法(CCSD)单点水平下,将B6S5^n(n=0,+1,+2)作为基础结构研究证实了S原子对于形成B平面多配位结构具有良好的作用.研究发现,B6S5^n(n=0,+1,+2)3种价态下最稳定和次稳定结构均为纯平面结构,仅在不同电子数下两者的能量次序发生改变.中性的B6S5因满足18电子规则其最稳定结构具有D5h对称性,且中心B为平面五配位.在B6S5^+和B6S5^2+中,其17电子和16电子时的最稳定结构中的所有B均为平面四配位.18电子的B6S5更为稳定.

At the level of B3LYP/def2-TZVP optimization and CCSD single point energy,B6S5^n(n=0,+1,+2)was utilized to validate the valuable effect of peripheral sulfur atom on constructing planar coordinated boron.The structures of global energy minimum(GEM)and the second lowest energy minimum in three charge states are purely planar ones,and their structures are very similar.Only their order is exchanged with the loss of the electrons.There exists a planar pentacoordinate boron in the GEM structure of D5h-B6S5 due to the 18 electron rule,and there are all the planar tetracoordinate borons in the GEM structure of B6S5^n(n=0,+1,+2).Meanwhile,the sulfur-bridging bonding is another key factor to maintain their planar molecular structures.