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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Binding between Ground-State Aluminum Ions and Small Molecules: Al~+·(H_2/CH_4/C_2H_2/C_2H_4/C_2H_6)_(n·) Can Al~+ Insert into H_2?
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Binding between Ground-State Aluminum Ions and Small Molecules: Al~+·(H_2/CH_4/C_2H_2/C_2H_4/C_2H_6)_(n·) Can Al~+ Insert into H_2?

机译：基态铝离子与小分子之间的结合：Al〜+·（H_2 / CH_4 / C_2H_2 / C_2H_4 / C_2H_6）_（n·）Al〜+可以插入H_2吗？

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Binding energies and entropies have been measured for the attachment of up to four H_2 ligands and six small hydrocarbons to ground-state Al~+ ions (~1S, 3s~2). Bond energies are typically very weak compared with analogous transition metal ion or the isovalent boron ion systems. Bond energies for the first ligand addition to Al~+ are 1.4 (H_2), 6.1 (CH_4), 9.3 (C_2H_6), 14.0 (C_2H_2), and 15.1 kcal/mol for C_2H_4. The origin of the weak bonding lies primarily in the large, repulsive 3s orbital, which prevents close approach by the ligands. In addition, the lack of low-energy acceptor orbitals on the Al~+ ion minimizes electron donation to the metal ion and also reduces the Al~+/ligand attraction. Finally, the lack of low lying, occupied π-type orbitals prevents donation from the Al~+ to the σ~* orbitals on the ligands. A very detailed theoretical examination of the Al~+(H_2)_n cluster energetics was also made. The purpose was to investigate the possibility of insertion by the Al~+ into the H-H bond via σ bond activation, as is found with the isovalent B~+ ion. The calculations showed that the inserted HAlH~+ ion is stable but that its formation is endothermic by 10.9 kcal/mol with respect to the separated reactants. The inserted HAlH~+(H_2)_2 ion, however, appears to be almost isoenergetic with the uninserted Al~+(H_2)_3 isomeric cluster.
机译：已测量了最多四个H_2配体和六个小烃与基态Al〜+离子（〜1S，3s〜2）的结合能和熵。与类似的过渡金属离子或等价硼离子系统相比，键能通常非常弱。对于Al 2+而言，第一配体加成的键能为1.4（H_2），6.1（CH_4），9.3（C_2H_6），14.0（C_2H_2）和对于C_2H_4为15.1kcal / mol。弱键的起源主要在于大的排斥性3s轨道，这阻止了配体的紧密接近。此外，Al〜+离子上缺乏低能受体轨道使电子对金属离子的贡献最小化，并且也降低了Al〜+ /配体的吸引。最后，缺乏低位，占据的π型轨道阻止了Al〜+向配体上的σ〜*轨道的捐赠。还对Al〜+（H_2）_n团簇的能量学进行了非常详细的理论研究。目的是研究同价的B〜+离子发现的Al〜+通过σ键活化插入H-H键的可能性。计算表明，插入的HAlH +离子是稳定的，但相对于分离的反应物，其形成的吸热峰为10.9 kcal / mol。然而，插入的HAlH〜+（H_2）_2离子似乎与未插入的Al〜+（H_2）_3异构簇几乎等能量。

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