Schalley Christoph A, Müller Thomas, Linnartz Petra, Witt Matthias, Schäfer Mathias, Lützen Arne
Kekulé-Institut für Organische Chemie und Biochemie Universität Bonn Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany.
Chemistry. 2002 Aug 2;8(15):3538-51. doi: 10.1002/1521-3765(20020802)8:15<3538::AID-CHEM3538>3.0.CO;2-W.
A detailed mass spectrometric characterization of self-assembling polynuclear metal complexes is described. The complexes can only be ionized as intact species under a surprisingly narrow range of conditions by electrospray ionization. Comparison with the results from NMR experiments shows that several solution-phase features of these squares and triangles (such as trends in bond energies, ligand-exchange reactions, or square-triangle equilibria) are qualitatively reflected in the gas-phase data. Consequently, mass spectrometry represents a valuable method for the characterization of these compounds. Nevertheless, the formation of unspecific aggregates during the ionization process occurs and its implications are discussed. Beyond the chemistry in solution, the fragmentation pathways of these complexes in the gas phase have been studied by infrared multiphoton dissociation (IRMPD) experiments. The results of IRMPD studies allow us to draw conclusions with respect to the structure and energetics of fragmentation products. In this tandem MS experiment, reaction pathways can be observed directly which can hardly be analyzed in solution. According to these results, the equilibration of triangles and squares involves the supramolecular analogue of a neighboring-group effect.
本文描述了自组装多核金属配合物的详细质谱表征。通过电喷雾电离，这些配合物仅在令人惊讶的狭窄条件范围内才能作为完整物种被电离。与核磁共振实验结果的比较表明，这些正方形和三角形的几个溶液相特征（如键能趋势、配体交换反应或正方形 - 三角形平衡）在气相数据中得到了定性反映。因此，质谱法是表征这些化合物的一种有价值的方法。然而，在电离过程中会形成非特异性聚集体，并对其影响进行了讨论。除了溶液中的化学性质外，还通过红外多光子解离（IRMPD）实验研究了这些配合物在气相中的碎裂途径。IRMPD研究结果使我们能够就碎裂产物的结构和能量学得出结论。在这个串联质谱实验中，可以直接观察到在溶液中难以分析的反应途径。根据这些结果，三角形和正方形的平衡涉及邻基效应的超分子类似物。
