Institute of Engineering Innovation, School of Engineering, The University of Tokyo , Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan.
J Am Chem Soc. 2014 Jul 9;136(27):9719-31. doi: 10.1021/ja5044243. Epub 2014 Jun 25.
A series of dinitrogen-bridged dimolybdenum-dinitrogen complexes bearing 4-substituted PNP-pincer ligands are synthesized by the reduction of the corresponding molybdenum trichloride complexes under 1 atm of molecular dinitrogen. In accordance with a theoretical study, the catalytic activity is enhanced by the introduction of an electron-donating group to the pyridine ring of PNP-pincer ligand, and the complex bearing 4-methoxy-substituted PNP-pincer ligands is found to work as the most effective catalyst, where 52 equiv of ammonia are produced based on the catalyst (26 equiv of ammonia based on each molybdenum atom of the catalyst), together with molecular dihydrogen as a side-product. Time profiles for the catalytic reactions indicate that the rates of the formation of ammonia and molecular dihydrogen depend on the nature of the substituent on the PNP-pincer ligand of the complexes. The formation of ammonia and molecular dihydrogen is complementary in the reaction system.
一系列含有 4-取代 PNP-钳形配体的二氮桥联二钼-二氮配合物是通过在 1 个大气压的分子氮下还原相应的三氯化钼配合物合成的。根据理论研究，在 PNP-钳形配体的吡啶环上引入供电子基团可以提高催化活性，而含有 4-甲氧基取代 PNP-钳形配体的配合物被发现是最有效的催化剂，基于催化剂（基于催化剂的每个钼原子的 26 当量）产生了 52 当量的氨，以及作为副产物的分子氢气。催化反应的时间曲线表明，氨和分子氢气的形成速率取决于配合物中 PNP-钳形配体取代基的性质。在反应体系中，氨和分子氢气的形成是互补的。
