摘要
我们通过实验和理论计算手段呈现出水合肼在MoO_2晶体表面的转氢过程,MoO_2独特的金属性-碱性双功能特征在催化转氢过程中起到了重要的作用。密度泛函理论(DFT)计算表明,比起N-N键的断裂,MoO_2优先催化肼分子中N-H键的选择性断裂,在Mo,O多核位点处生成异裂的H~(δ-)和H~(δ+)物种,使得MoO_2不同于其它金属氧化物。相比较于C=C,C≡C和C≡N基团,MoO_2在室温甚至0℃条件下选择性高效催化硝基还原。
We present an experimental and computational study of the elementary steps of hydrazine hydrogen transfer on crystalline MoO_2, and demonstrate its unique bifunctional metallic-basic properties in a catalytic hydrogenation reaction. Density functional theory(DFT) calculations suggest that the stepwise hydrogen transfer via the prior cleavage of the N–H bond rather than the N–N bond, is the key step to create the dissociated hydride and proton species on the dual Mo and O sites, marking its difference with common oxides. Crystalline MoO_2 shows exceptionally high chemoselectivity toward the nitro reduction over C=C, C≡C, and C≡N groups at room temperature and lower, down to 0 ℃.
引文
[1]Zhang,C.;Lu,J.;Li,M.;Wang,Y.;Zhang,Z.;Chen,H.;Wang,F.Green Chem.2016,DOI:10 .1039/c5gc02460a.