Herber Ina, Tang Wai-Kit, Wong Ho-Yin, Lam Tim-Wai, Siu Chi-Kit, Beyer Martin K
†Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, 24098 Kiel, Germany.
‡Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
J Phys Chem A. 2015 Jun 4;119(22):5566-78. doi: 10.1021/acs.jpca.5b02946. Epub 2015 May 21.
Reactions of M(H2O)n, M = Cr, Mn, Fe, Co, Ni, Cu, and Zn, n < 50, with CH3CN are studied in the gas phase by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Sequential uptake of 4-6 acetonitrile molecules is observed for all metals. Rate constants show a weak dependence on both the metal and the number of acetonitrile molecules already in the cluster. Nanocalorimetry yields the enthalpy of the first reaction step. For most metals, this is consistent with a ligand exchange of water against acetonitrile. For M = Cr, however, the strong exothermicity of ΔE(nc) = -195 ± 26 kJ mol(-1) suggests an electron transfer from Cr(+) to CH3CN. Exclusively for M = Zn, a relatively slow oxidation of the metal center to Zn(2+), with formation of ZnOH(+) and release of CH3CNH(•) or CH3CHN(•) is observed. Density functional theory molecular dynamics simulations and geometry optimizations show that charge transfer from Zn(+) to CH3CN as well as the subsequent proton transfer are associated with a barrier.
采用傅里叶变换离子回旋共振（FT-ICR）质谱法在气相中研究了M(H₂O)ₙ（M = Cr、Mn、Fe、Co、Ni、Cu和Zn，n < 50）与CH₃CN的反应。观察到所有金属都能依次吸收4 - 6个乙腈分子。速率常数对金属以及簇中已有的乙腈分子数量的依赖性较弱。纳米量热法得出了第一步反应的焓。对于大多数金属来说，这与水和乙腈之间的配体交换是一致的。然而，对于M = Cr，ΔE(nc) = -195 ± 26 kJ mol⁻¹的强放热表明有电子从Cr(⁺)转移到CH₃CN。仅对于M = Zn，观察到金属中心相对缓慢地氧化为Zn(²⁺)，形成ZnOH(⁺)并释放出CH₃CNH(•)或CH₃CHN(•)。密度泛函理论分子动力学模拟和几何优化表明，从Zn(⁺)到CH₃CN的电荷转移以及随后的质子转移都存在一个势垒。
