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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Triple-decker sandwiches and related compounds of the first-row transition metals containing cyclopentadienyl and benzene rings
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Triple-decker sandwiches and related compounds of the first-row transition metals containing cyclopentadienyl and benzene rings

机译：含环戊二烯基和苯环的第一行过渡金属的三层甲板三明治和相关化合物

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摘要

The triple-decker sandwich compound trans-Cp_2V _2(η~6:η~6-μ-C_6H _6) has been synthesized, as well as slipped sandwich compounds of the type trans-Cp_2Co_2(η~4:η~4- μ-arene) and the cis-Cp_2Fe_2(η~4: η~4-μ-C_6R_6) derivatives with an Fe-Fe bond (Cp = η~5-cyclopentadienyl). Theoretical studies show that the symmetrical triple-decker sandwich structures trans-Cp_2M _2(η~6:η~6-μ-C_6H _6) are the global minima for M = Ti, V, and Mn but lie ～10 kcal/mol above the global minimum for M = Cr. The nonbonding M ? M distances and spin states in these triple decker sandwich compounds can be related to the occupancies of the frontier bonding molecular orbitals. The global minimum for the chromium derivative is a singlet spin state cis-Cp _2Cr_2(η~4:η~4-μ-C _6H_6) structure with a very short CrCr distance of 2.06 ?, suggesting a formal quadruple bond. A triplet state cis-Cp _2Cr_2(η~4:η~4-μ-C _6H_6) structure with a predicted CrCr distance of 2.26 ? lies only ～3 kcal/mol above this global minimum. For the later transition metals the global minima are predicted to be cis-Cp_2M _2(η~6:η~6-μ-C_6H _6) structures with a metal-metal bond, rather than triple decker sandwiches. These include singlet cis-Cp_2Fe_2(η ~4:η~4-μ-C_6H_6) with a predicted Fe = Fe double bond distance of 2.43 ?, singlet cis-Cp_2Co _2(η~3:η~3-μ-C_6H _6) with a predicted Co-Co single bond distance of 2.59 ?, and triplet cis-Cp_2Ni_2(η~3:η~3- μ-C_6H_6) with a predicted Ni-Ni distance of 2.71 ?.
机译：合成了三层夹层化合物trans-Cp_2V _2（η〜6：η〜6-μ-C_6H_6）以及反式Cp_2Co_2（η〜4：η〜4-μ -芳烃）和具有Fe-Fe键的顺式Cp_2Fe_2（η〜4：η〜4-μ-C_6R_6）衍生物（Cp =η〜5-环戊二烯基）。理论研究表明，对称的三层双层三明治结构反式Cp_2M _2（η〜6：η〜6-μ-C_6H_6）是M = Ti，V和Mn的全局最小值，但在〜10 kcal / mol以上M = Cr的全局最小值。非键M？这些三层夹层化合物中的M距离和自旋态可能与边界键分子轨道的占有率有关。铬衍生物的整体最小值是单峰自旋态顺式-Cp _2Cr_2（η〜4：η〜4-μ-C_6H_6）结构，CrCr距离非常短，为2.06 ?，表明存在正式的四键。三重态cis-Cp _2Cr_2（η〜4：η〜4-μ-C_6H_6）结构，预计CrCr距离为2.26？比这个全球最低值仅高出约3 kcal / mol。对于后来的过渡金属，总的最小值被预测为具有金属-金属键的顺式-Cp_2M _2（η〜6：η〜6-μ-C_6H_6）结构，而不是三层夹层结构。这些包括单峰的cis-Cp_2Fe_2（η〜4：η〜4-μ-C_6H_6）和预测的Fe = Fe双键距离为2.43 ?、单峰的cis-Cp_2Co _2（η〜3：η〜3-μ-C_6H_6 ）的Co-Co单键预测距离为2.59 ?,三重态cis-Cp_2Ni_2（η〜3：η〜3-μ-C_6H_6），Ni-Ni预测距离为2.71 ?.

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