Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States.
Ames Laboratory , U.S. Department of Energy , Ames , Iowa 50011 , United States.
J Am Chem Soc. 2018 May 23;140(20):6308-6316. doi: 10.1021/jacs.8b00995. Epub 2018 Apr 9.
The chemical and electronic interactions of organometallic species with metal oxide support materials are of fundamental importance for the development of new classes of catalytic materials. Chemisorption of Cp*(PMe)IrMe on sulfated alumina (SA) and sulfated zirconia (SZ) led to an unexpected redox mechanism for deuteration of the ancillary Cp* ligand. Evidence for this oxidative mechanism was provided by studying the analogous homogeneous reactivity of the organometallic precursors toward trityl cation ([PhC]), a Lewis acid known to effect formal hydride abstraction by one-electron oxidation followed by hydrogen abstraction. Organometallic deuterium incorporation was found to be correlated with surface sulfate concentration as well as the extent of dehydration under thermal activation conditions of SA and SZ supports. Surface sulfate concentration dependence, in conjunction with a computational study of surface electron affinity, indicates an electron-deficient pyrosulfate species as the redox-active moiety. These results provide further evidence for the ability of sulfated metal oxides to participate in redox chemistry not only toward organometallic complexes but also in the larger context of their application as catalysts for the transformation of light alkanes.
有机金属物种与金属氧化物载体材料的化学和电子相互作用对于开发新型催化材料至关重要。Cp*(PMe)IrMe 在硫酸化氧化铝 (SA) 和硫酸化氧化锆 (SZ) 上的化学吸附导致辅助 Cp*配体的氘代反应出现了意想不到的氧化还原机制。通过研究有机金属前体对三苯甲基阳离子 ([PhC]) 的类似均相反应性，为这种氧化机制提供了证据，三苯甲基阳离子是一种众所周知的路易斯酸，能够通过单电子氧化进行形式氢化物的提取，然后进行氢提取。发现有机金属氘的掺入与表面硫酸盐浓度以及 SA 和 SZ 载体在热激活条件下的脱水程度有关。表面硫酸盐浓度的依赖性，结合对表面电子亲合能的计算研究，表明氧化还原活性部分是缺电子焦硫酸盐物种。这些结果进一步证明了硫酸化金属氧化物不仅能够参与有机金属配合物的氧化还原化学，而且能够在其作为轻烷烃转化催化剂的更大背景下参与氧化还原化学。
