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. 2006 Feb 2;110(4):1232-41. doi: 10.1021/jp0526602.
The chemistry of carbon dioxide has been surveyed systematically with 46 atomic cations at room temperature using an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. The atomic cations were produced at ca. 5500 K in an ICP source and allowed to cool radiatively and to thermalize by collisions with Ar and He atoms prior to reaction downstream in a flow tube in helium buffer gas at 0.35 +/- 0.01 Torr and 295 +/- 2 K. Rate coefficients and products were measured for the reactions of first-row atomic ions from K(+) to Se(+), of second-row atomic ions from Rb(+) to Te(+) (excluding Tc(+)), and of third-row atomic ions from Cs(+) to Bi(+). CO(2) was found to react in a bimolecular fashion by O atom transfer only with 9 early transition-metal cations: the group 3 cations Sc(+), Y(+), and La(+), the group 4 cations Ti(+), Zr(+), and Hf(+), the group 5 cations Nb(+) and Ta(+), and the group 6 cation W(+). Electron spin conservation was observed to control the kinetics of O atom transfer. Addition of CO(2) was observed for the remaining 37 cations. While the rate of addition was not measurable some insight was obtained into the standard free energy change, DeltaG(o), for CO(2) ligation from equilibrium constant measurements. A periodic variation in DeltaG(o) was observed for first row cations that is consistent with previous calculations of bond energies D(0)(M(+)-CO(2)). The observed trends in D(0) and DeltaG(o) are expected from the variation in electrostatic attraction between M(+) and CO(2) which follows the trend in atomic-ion size and the trend in repulsion between the orbitals of the atomic cations and the occupied orbitals of CO(2). Higher-order CO(2) cluster ions with up to four CO(2) ligands also were observed for 24 of the atomic cations while MO(2)(+) dioxide formation by sequential O atom transfer was seen only with Hf(+), Nb(+), Ta(+), and W(+).
利用电感耦合等离子体/选择离子流动管（ICP/SIFT）串联质谱仪，在室温下系统地研究了二氧化碳与46种原子阳离子的化学反应。原子阳离子在ICP源中约5500K的温度下产生，在与氩原子和氦原子发生辐射冷却及碰撞热化后，进入氦缓冲气体中、压力为0.35±0.01托、温度为295±2K的流动管下游进行反应。测量了从K(+)到Se(+)的第一排原子离子、从Rb(+)到Te(+)（不包括Tc(+)）的第二排原子离子以及从Cs(+)到Bi(+)的第三排原子离子反应的速率系数和产物。发现CO₂仅通过氧原子转移以双分子方式与9种早期过渡金属阳离子发生反应：第3族阳离子Sc(+)、Y(+)和La(+)，第4族阳离子Ti(+)、Zr(+)和Hf(+)，第5族阳离子Nb(+)和Ta(+)，以及第6族阳离子W(+)。观察到电子自旋守恒控制着氧原子转移的动力学。对于其余37种阳离子，观察到了CO₂的加成反应。虽然加成速率无法测量，但通过平衡常数测量对CO₂配位的标准自由能变化ΔG⁰有了一些了解。观察到第一排阳离子的ΔG⁰呈周期性变化，这与先前对键能D₀(M⁺-CO₂)的计算结果一致。从M⁺与CO₂之间静电吸引力的变化可以预期D₀和ΔG⁰的观察趋势，这种变化遵循原子离子大小的趋势以及原子阳离子轨道与CO₂占据轨道之间的排斥趋势。对于24种原子阳离子，还观察到了含有多达四个CO₂配体的高阶CO₂簇离子，而仅在Hf(+)、Nb(+)、Ta(+)和W(+)中观察到通过连续氧原子转移形成MO₂⁺二氧化物。
