Multem Arie J H, Tripodi Guilherme L, Roithová Jana
Department of Spectroscopy and Catalysis, Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
J Am Chem Soc. 2023 Dec 20;145(50):27555-27562. doi: 10.1021/jacs.3c08925. Epub 2023 Dec 7.
Metal hydride complexes are essential intermediates in hydrogenation reactions. The hydride-donor ability determines the scope of use of these complexes. We present a new, simple mass-spectrometry method to study the hydride-donor ability of metal hydrides using a series of 18 iron, cobalt, and nickel complexes with and based ligands (L). The mixing of [(L)M(OTf)] with NaBH forms [(L)M(BH)] (M = Fe, Co, Ni) that can be detected by electrospray ionization mass spectrometry. Energy-resolved collision-induced dissociations of [(L)M(BH)] provide threshold energies (Δ) for the formations of [(L)M(H)] that correlate well with the hydride donor ability of the metal hydride complexes. We studied the vibrational and electronic spectra of the generated metal hydrides, assigned their structure and spin state, and demonstrated a good correlation between Δ and the M-H stretching vibration frequencies. The Δ also correlates with reaction rates for hydride transfer reactivity in the gas phase and known reactivity trends in the solution phase.
金属氢化物配合物是氢化反应中的重要中间体。氢化物供体能力决定了这些配合物的使用范围。我们提出了一种新的、简单的质谱方法，使用一系列18种带有[具体配体]配体（L）的铁、钴和镍配合物来研究金属氢化物的氢化物供体能力。[(L)M(OTf)]与NaBH混合形成[(L)M(BH)]（M = Fe、Co、Ni），可通过电喷雾电离质谱检测。[(L)M(BH)]的能量分辨碰撞诱导解离为[(L)M(H)]的形成提供了阈值能量（Δ），这与金属氢化物配合物的氢化物供体能力有很好的相关性。我们研究了生成的金属氢化物的振动和电子光谱，确定了它们的结构和自旋状态，并证明了Δ与M - H伸缩振动频率之间有良好的相关性。Δ还与气相中氢化物转移反应性的反应速率以及溶液相中已知的反应性趋势相关。
