Department of Chemistry, Institute of Inorganic Chemistry, University of Cologne, Greinstrasse 6, 50939 Köln, Germany.
Chemphyschem. 2012 Jun 4;13(8):2037-45. doi: 10.1002/cphc.201200132. Epub 2012 Mar 22.
A series of aluminium complex ions with trifluoromethyl-heteroarylalkenolato (TMHA) ligands are studied by gas-phase infrared multiphoton-dissociation (IRMPD) spectroscopy and computational modelling. The selected series of aluminium TMHA complex ions are promising species for the initial study of intrinsic binding characteristics of Al(III) cations in the gas phase as corresponding molecular ions. They are readily available for examination by (+) and (-) electrospray ionization mass spectrometry (ESI-MS) by spraying of [Al(3+)⋅(L(-))(3)] solutions. The complex ions under investigation contain trivalent Al(3+) cations with two chelating anionic enolate ligands, Al(3+)⋅(L(-))(2), providing insights in the nature of the heteroatom-Al bonds. Additionally, the structure of a deprotonated benzimidazole ligand, L(-,) and an anionic complex ion of Al(III) with two doubly deprotonated benzimidazole ligands, Al(3+)⋅(L(2-))(2), are examined by (-)ESI-IRMPD spectroscopy. Experimental and computational results are highly consistent and allow a reliable identification of the ion structures. In all complex ions examined the planar TMHA ligands are oriented perpendicular to each other around the metal ion, leading to a tetrahedral coordination sphere in which aluminium interacts with the enolate oxygen and heteroaryl nitrogen atoms available in each of the bidentate ligands.
一系列含三氟甲基杂芳烯醇（TMHA）配体的铝配合物离子通过气相红外多光子解离（IRMPD）光谱和计算建模进行了研究。所选系列的铝 TMHA 配合物离子是研究气态中 Al(III)阳离子内在结合特性的理想候选物，因为它们是相应的分子离子。通过喷雾[Al(3+)·(L(-))(3)]溶液，很容易通过正（+）和负（-）电喷雾电离质谱（ESI-MS）进行检查。所研究的配合物离子包含三价 Al(3+)阳离子，带有两个螯合阴离子烯醇配体[Al(3+)·(L(-))(2)]+，提供了关于杂原子-Al 键性质的见解。此外，通过负电喷雾 IRMPD 光谱还研究了去质子化苯并咪唑配体 L(-,)和带有两个双去质子化苯并咪唑配体的 Al(III)的阴离子配合物离子[Al(3+)·(L(2-))(2)]-。实验和计算结果高度一致，允许可靠地识别离子结构。在所检查的所有配合物离子中，平面 TMHA 配体彼此垂直定向，围绕金属离子形成四面体配位球体，其中铝与每个双齿配体中可用的烯醇氧和杂芳环氮原子相互作用。
