Bis(3,5-dimethylpyrazol-1-yl)acetate bound to titania and complexed to molybdenum dioxido as a bidentate N,N′-ligand. Direct comparison with a bipyridyl analog in a photocatalytic arylalkane oxidation by O2
作者:Nelson J. Castellanos、Fernando Martínez、Edgar A. Páez-Mozo、Fabio Ziarelli、Henri Arzoumanian
DOI:10.1007/s11243-012-9631-2
日期:2012.10
Bis(3,5-dimethylpyrazol-1-yl)acetate, well known as a tridentate N,N,O ligand, was bound to MoO2Cl2 in a bidentate N,N manner by anchoring covalently, at first, the ligand onto a titanium oxide surface, followed by its complexation with the molybdenum dioxo entity. It was fully characterized by 13CPMAS NMR and FT-IR spectroscopy. The tethered complex was directly compared with an analogous bipyridyl species in the catalytic ethylbenzene oxidation by O2 at room temperature, atmospheric pressure, and under visible light. The bis(pyrazol-1-yl) catalyst exhibited a significant initial higher oxygen atom transfer (OAT) capability, well in accord with its electron donating property. It was, unfortunately, hampered by a premature leaching phenomenon, totally absent in the comparable bipyridyl system.
双(3,5-二甲基吡唑-1-基)乙酸酯是众所周知的三叉N,N,O配体,通过首先将配体共价锚定在氧化钛表面,然后与二氧代钼实体络合,以双叉N,N方式与MoO2Cl2结合。13CPMAS NMR 和 FT-IR 光谱对其进行了全面表征。在室温、常压和可见光条件下,在 O2 催化乙苯氧化过程中,该系留配合物与类似的双吡啶基物种进行了直接比较。双(吡唑-1-基)催化剂表现出明显较高的氧原子转移(OAT)能力,这与其电子捐赠特性十分吻合。遗憾的是,它受到了过早沥滤现象的阻碍,而这种现象在类似的双吡啶体系中完全不存在。