Ding Yong-Qi, Chen Zhi-Ying, Li Zi-Yu, Cheng Xin, Wang Ming, Ma Jia-Bi
Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, P. R. China.
State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
J Phys Chem A. 2022 Mar 10;126(9):1511-1517. doi: 10.1021/acs.jpca.1c10868. Epub 2022 Feb 28.
Alkali atoms are usually used as promoters to significantly increase the catalytic activity of transition-metal catalysts in a wide range of reactions such as dinitrogen conversion reactions. However, the role of alkali metal atoms remains controversial. Herein, a series of quaternary cluster anions containing lithium atoms NbLiNO have been synthesized and reacted with N at room temperature. The detailed experimental and theoretical investigations indicate that NbLiNO is capable to cleave the N≡N bond and the Li atoms in NbLiNO act as electron donors in the N reduction reaction. With the increase in the number of oxygen atoms, the reactivity toward N is reduced from adsorption via a side-on end-on mode in NbLiNO to the inertness of NbLiNO. In NbLiNO anions, the Li atoms are bonded with oxygen atoms, acting as structural units to stabilize structures. Therefore, the roles of alkali atoms are able to change with different chemical environments of active sites. For the first time, we reveal how the number of ligands (oxygen atoms herein) can be used to finely regulate the reactivity toward N.
碱金属原子通常用作促进剂，以显著提高过渡金属催化剂在诸如二氮转化反应等广泛反应中的催化活性。然而，碱金属原子的作用仍存在争议。在此，一系列含锂原子的四元簇阴离子NbLiNO已被合成，并在室温下与N反应。详细的实验和理论研究表明，NbLiNO能够裂解N≡N键，并且NbLiNO中的Li原子在N还原反应中充当电子供体。随着氧原子数目的增加，对N的反应性从NbLiNO中通过侧端-端模式的吸附降低到NbLiNO的惰性。在NbLiNO阴离子中，Li原子与氧原子键合，作为稳定结构的结构单元。因此，碱原子的作用能够随着活性位点的不同化学环境而改变。我们首次揭示了配体（此处为氧原子）的数量如何能够用于精细调节对N的反应性。
