摘要：The simple homodinuclear M-M single bonds for group II and XII elements are difficult to obtain as a result of the fulfilled s2electronic configurations,consequently,a dicationic prototype is often utilized to design the M^+-M^+single *** studies generally use sterically bulky organic ligands L^-to synthesize the compounds in the L^--M^+-M^+-***,here we report the design of Mg-Mg and Zn-Zn single bonds in two ligandless clusters,Mg2B7-and Zn2B7-,using density functional theory *** global minima of both of the clusters are in the form of M2^2+(B7^3-),where the M-M single bonds are positioned above a quasi-planar hexagonal B7 *** bonding analyses further confirm the existence of Mg-Mg and Zn-Zn single bonds in these clusters,which are driven by the unusually stable B7^3-moiety that is bothσandπ*** detachment energies of Mg2B7-and Zn2B7-are calculated to be 2.79 e V and 2.94 e V,respectively,for the future comparisons with experimental data.

摘要：《文选》李善注和五臣注之争由来已久,李善注释义广引,五臣注释义简明。两者所注阮籍《咏怀诗十七首》的异同展现出了各自的优长,李善注旁征博引、追本溯源,五臣注精简务实、明白畅达。但是两者又有着各自的不足,李善注过于依赖前人的注解而忽视回归文本,五臣注的题解亦有局限。不过两者“文”“质”相辅,优势互补,于《文选》的传播均有着不可替代的意义。