Cheng Ping, Koyanagi Gregory K, Bohme Diethard K
Department of Chemistry, Centre for Research in Mass Spectrometry and Centre for Research in Earth and Space Science, York University, Toronto, Ontario, Canada, M3J 1P3.
J Phys Chem A. 2007 Sep 6;111(35):8561-73. doi: 10.1021/jp072661p. Epub 2007 Aug 16.
Reactions of heavy water, D(2)O, have been measured with 46 atomic metal cations at room temperature in a helium bath gas at 0.35 Torr using an inductively coupled plasma/selected ion flow tube tandem mass spectrometer. The atomic cations were produced at ca. 5500 K in an ICP source and were allowed to decay radiatively and thermalize by collisions with Ar and He atoms prior to reaction. Rate coefficients and product distributions are reported for the reactions of fourth-row atomic cations from K+ to Se+, of fifth-row atomic cations from Rb+ to Te+ (excluding Tc+), and of sixth-row atomic cations from Cs+ to Bi+. Primary reaction channels were observed leading to O-atom transfer, OD transfer, and D2O addition. O-Atom transfer occurs almost exclusively (>or=90%) in the reactions with most early transition-metal cations (Sc+, Ti+, V+, Y+, Zr+, Nb+, Mo+, Hf+, Ta+, and W+) and to a minor extent (10%) with one main-group cation (As+). OD transfer is observed to occur only with three cations (Sr+, Ba+, and La+). Other cations, including most late transition and main-group cations, were observed to react with D2O exclusively and slowly by D2O addition or not at all. O-Atom transfer proceeds with rate coefficients in the range of 8.1 x 10(-13) (As+) to 9.5 x 10(-10) (Y+) cm3 molecule(-1)(s-1) and with efficiencies below 0.1 and even below 0.01 for the fourth-row atomic cations V+ (0.0032) and As+ (0.0036). These low efficiencies can be understood in terms of the change in spin required to proceed from the reactant to the product potential energy surfaces. Higher order reactions are also measured. The primary products, NbO+, TaO+, MoO+, and WO+, are observed to react further with D(2)O by O-atom transfer, and ZrO+ and HfO+ react further through OD group abstraction. Up to five D(2)O molecules were observed to add sequentially to selected M+ and MO+ as well as MO2+ cations and four to MO(2)D+. Equilibrium measurements for sequential D(2)O addition to M+ are also reported. The periodic variation in the efficiency (k/k(c)) of the first addition of D(2)O appears to be similar to the periodic variation in the standard free energy (DeltaG degrees) of hydration.
利用电感耦合等离子体/选择离子流管串联质谱仪，在室温下于0.35托的氦浴气中，测量了重水（D₂O）与46种原子态金属阳离子的反应。原子阳离子在电感耦合等离子体源中约5500K的温度下产生，并在反应前通过与氩原子和氦原子的碰撞进行辐射衰变和热化。报道了第四周期从K⁺到Se⁺、第五周期从Rb⁺到Te⁺（不包括Tc⁺）以及第六周期从Cs⁺到Bi⁺的原子阳离子反应的速率系数和产物分布。观察到主要反应通道导致氧原子转移、OD转移和D₂O加成。氧原子转移几乎只发生在与大多数早期过渡金属阳离子（Sc⁺、Ti⁺、V⁺、Y⁺、Zr⁺、Nb⁺、Mo⁺、Hf⁺、Ta⁺和W⁺）的反应中（≥90%），与一种主族阳离子（As⁺）的反应中占比小（10%）。仅观察到三种阳离子（Sr⁺、Ba⁺和La⁺）发生OD转移。观察到其他阳离子，包括大多数晚期过渡金属和主族阳离子，仅通过D₂O加成与D₂O缓慢反应或根本不反应。氧原子转移的速率系数范围为8.1×10⁻¹³（As⁺）至9.5×10⁻¹⁰（Y⁺）cm³·分子⁻¹·s⁻¹，对于第四周期原子阳离子V⁺（0.0032）和As⁺（0.0036），其效率低于0.1甚至低于0.01。这些低效率可以从反应物到产物势能面所需的自旋变化来理解。还测量了高阶反应。观察到主要产物NbO⁺、TaO⁺、MoO⁺和WO⁺通过氧原子转移与D₂O进一步反应，ZrO⁺和HfO⁺通过OD基团夺取进一步反应。观察到多达五个D₂O分子依次加成到选定 的M⁺、MO⁺以及MO₂⁺阳离子上，四个加成到MO₂D⁺上。还报道了D₂O依次加成到M⁺上的平衡测量结果。D₂O首次加成效率（k/k₀）的周期性变化似乎与水合标准自由能（ΔG°）的周期性变化相似。
