Institute of Inorganic Chemistry, Christian Albrechts University Kiel, Max-Eyth-Strasse 2, 24118, Kiel, Germany.
Institute of Experimental and Applied Physics, Christian Albrechts University Kiel, Leibnizstrasse 19, 24118, Kiel, Germany.
Chemistry. 2018 Jul 25;24(42):10732-10744. doi: 10.1002/chem.201800911. Epub 2018 Jun 27.
Activating small molecules with transition metal complexes adsorbed on metal surfaces is a novel approach combining aspects of homogeneous and heterogeneous catalysis. In order to study the influence of an Au(111) substrate on the activation of the small-molecule ligand carbon monoxide, a molybdenum tricarbonyl complex containing a PN P pincer ligand was synthesized and investigated in the bulk, in solution, and adsorbed on an Au(111) surface. By means of a platform approach, a perpendicular orientation of the molybdenum complex was achieved and confirmed by IRRAS and NEXAFS. By using vibrational spectroscopy (IR, Raman, IRRAS) coupled to DFT calculations, the influence of the metal substrate on the activation of the CO ligands bound to the molybdenum complex was determined. The electron-withdrawing behavior of gold causes an overall shift of the CO stretching vibrations to higher frequencies, which is partly compensated by dynamic charge transfer from the substrate to the molybdenum center, which increases its (dynamic) polarizability.
在金属表面吸附的过渡金属配合物上激活小分子是一种将均相催化和多相催化结合起来的新方法。为了研究 Au(111) 衬底对小分子配体一氧化碳的活化的影响，合成了一种含有 PN P 夹钳配体的三羰基钼配合物，并在本体、溶液中和吸附在 Au(111)表面上进行了研究。通过平台方法，实现了钼配合物的垂直取向，并通过 IRRAS 和 NEXAFS 得到了证实。通过振动光谱（IR、Raman、IRRAS）与密度泛函理论计算相结合，确定了金属衬底对与钼配合物结合的 CO 配体的活化的影响。金的吸电子行为导致 CO 伸缩振动整体向高频移动，这部分被来自衬底到钼中心的动态电荷转移部分补偿，从而增加了它的（动态）极化率。
