High-Resolution Electron Spectroscopy and Rotational Conformers of Group 6 Metal (Cr, Mo, and W) Bis(mesitylene) Sandwich Complexes

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• 作者：Sudesh Kumari ; Dong-Sheng Yang
• 刊名：Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：December 19, 2013
• 年：2013
• 卷：117
• 期：50
• 页码：13336-13344
• 全文大小：333K
• 年卷期：v.117,no.50(December 19, 2013)
• ISSN：1520-5215

文摘

Group 6 metal鈥揵is(mesitylene) sandwich complexes are produced by interactions between the laser-vaporized metal atoms and mesitylene vapor in a pulsed molecular beam source, identified by photoionization time-of-flight mass spectrometry, and studied by pulsed-field ionization zero-electron kinetic energy spectroscopy and density functional theory calculations. Although transition metal鈥揵is(arene) sandwich complexes may adopt eclipsed and staggered conformations, the group 6 metal鈥揵is(mesitylene) complexes are determined to be in the eclipsed form. In this form, rotational conformers with methyl group dihedral angles of 0 and 60掳 are identified for the Cr complex, whereas the 0掳 rotamer is observed for the Mo and W species. The 0掳 rotamer is in a C_2v symmetry with the neutral ground state of ¹A₁ and the singly positive charged ion state of ²A₁. The 60掳 rotamer is in a C_i symmetry with the neutral ground state of ¹A_g and the ion state of ²A_g. Partial conversion of the 60 to 0掳 rotamer is observed from He to He/Ar supersonic expansion for Cr鈥揵is(mesitylene). The unsuccessful observation of the 60掳 rotamer for the Mo and W complexes is the result of its complete conversion to the 0掳 rotamer in both He and He/Ar expansions. The adiabatic ionization energies of the 0掳 rotamers of the three complexes are in the order of Cr鈥揵is(mesitylene) < W鈥揵is(mesitylene) < Mo鈥揵is(mesitylene), which is different from that of the metal atoms. These metal鈥揵is(mesitylene) complexes have lower ionization energies than the corresponding metal鈥揵is(benzene) and 鈭抌is(toluene) species.