Catalytic N2 Reduction to Silylamines and Thermodynamics of N2 Binding at Square Planar Fe.
Catalytic N2 Reduction to Silylamines and Thermodynamics of N2 Binding at Square Planar Fe.
复制标题
DOI：
10.1021/jacs.7b04552
复制
发表时间：
2017-07
影响因子：
15
通讯作者：
Demyan E. Prokopchuk;Eric S. Wiedner;E. Walter;C. Popescu;N. Piro;W. Kassel;R. Bullock;Michael T. Mock
中科院分区：
文献类型：
--
作者：
Demyan E. Prokopchuk;Eric S. Wiedner;E. Walter;C. Popescu;N. Piro;W. Kassel;R. Bullock;Michael T. Mock
由四齿P4 N2配体施加的几何约束在稳定正方形平面Fe配合物与金属氧化态的变化中起着至关重要的作用。四方锥Fe 0（N2）（P4 N2）络合物在室温下催化N2转化为N（SiR 3）3（R = Me，Et），代表迄今为止任何Fe基N2甲硅烷基化催化剂的最高转换数（每个Fe中心高达65当量N（SiMe 3）3）。升高的N2压力（>1 atm）对催化作用有显著影响，增加N2溶解度和在Fe 0（N2）（P4 N2）处的热力学N2结合亲和力。高压电化学和变温紫外-可见光谱的组合被用来获得N2结合的热力学测量。此外，X射线晶体学，57 Fe穆斯堡尔谱和EPR谱被用来充分表征这些新化合物。Fe 0，Fe I和Fe II复合物的分析表明，N2结合跨越三个氧化态的自由能跨越超过37千卡mol-1。
The geometric constraints imposed by a tetradentate P4N2 ligand play an essential role in stabilizing square planar Fe complexes with changes in metal oxidation state. The square pyramidal Fe0(N2)(P4N2) complex catalyzes the conversion of N2 to N(SiR3)3 (R = Me, Et) at room temperature, representing the highest turnover number of any Fe-based N2 silylation catalyst to date (up to 65 equiv N(SiMe3)3 per Fe center). Elevated N2 pressures (>1 atm) have a dramatic effect on catalysis, increasing N2 solubility and the thermodynamic N2 binding affinity at Fe0(N2)(P4N2). A combination of high-pressure electrochemistry and variable-temperature UV-vis spectroscopy were used to obtain thermodynamic measurements of N2 binding. In addition, X-ray crystallography, 57Fe Mössbauer spectroscopy, and EPR spectroscopy were used to fully characterize these new compounds. Analysis of Fe0, FeI, and FeII complexes reveals that the free energy of N2 binding across three oxidation states spans more than 37 kcal mol-1.