Czerwinska Izabella, Far Johann, Kune Christopher, Larriba-Andaluz Carlos, Delaude Lionel, De Pauw Edwin
Laboratory of Mass Spectrometry, Department of Chemistry, Allée de la Chimie 3, Quartier Agora, Université de Liège, 4000 Liège, Belgium.
Department of Mechanical Engineering, Indiana University-Purdue University, Indianapolis, Indiana 46202-5132, USA.
Dalton Trans. 2016 Apr 21;45(15):6361-70. doi: 10.1039/c6dt00080k.
Ion mobility mass spectrometry (IM-MS) and collision-induced dissociation (CID) techniques were used to investigate the influence of the phosphine ligand on the physicochemical properties of [RuCl2(p-cymene)(PCy3)] (), [RuCl2(p-cymene)(PPh3)] (), and [RuCl2(p-cymene)(PTA)] () in the gas phase (PTA is 1,3,5-triaza-7-phosphaadamantane). Electrospray ionization of complexes and led to the corresponding RuCl(p-cymene)(PR3) ions via the dissociation of a chlorido ligand, whereas RAPTA-C () afforded two molecular ions by in-source oxidation (Ru(III)Cl2(p-cymene)(PTA)) or protonation (RuCl2(p-cymene)(PTA+H)). Control experiments showed that the balance between these two ionization paths was strongly influenced by the nature of the solvent used for infusion. Collision cross sections (CCSs) of the four molecular ions accurately reflected the variations of steric bulk inferred from the Tolman steric parameters (θ) of the phosphine ligands. Moreover, DFT calculations combined with a model based on the kinetic theory of gases (the trajectory method of the IMoS software) afforded reliable CCS predictions. The almost two times higher dipole moment of RuCl2(p-cymene)(PTA+H) (μ = 13.75 D) compared to Ru(III)Cl2(p-cymene)(PTA) (μ = 7.18 D) was held responsible for increased ion-induced dipole interactions with a polarizable drift gas such as N2. Further experiments with He and CO2 confirmed that increasing the polarizability of the buffer gas improved the separation between the two molecular ions derived from complex . The fragmentation patterns of complexes were determined by CID. The sequence of collision voltages at which 50% of a precursor ion dissociates (V50) recorded for the molecular ions derived from compounds was in good agreement with simple electronic considerations based on the donor strength of the phosphine ligand. Thus, the CCS and V50 parameters used to determine the shape and stability of ionic species in the gas phase are complementary to the Tolman steric and electronic parameters (θ and TEP) commonly used by organometallic chemists in condensed phases.
采用离子淌度质谱（IM-MS）和碰撞诱导解离（CID）技术，研究了膦配体对气相中[RuCl2(p-异丙基苯)(PCy3)]（）、[RuCl2(p-异丙基苯)(PPh3)]（）和[RuCl2(p-异丙基苯)(PTA)]（）（PTA为1,3,5-三氮杂-7-磷杂金刚烷）物理化学性质的影响。配合物和的电喷雾电离通过氯配体的解离产生相应的[RuCl(p-异丙基苯)(PR3)]⁺离子，而RAPTA-C（）通过源内氧化（[Ru(III)Cl2(p-异丙基苯)(PTA)]⁺）或质子化（[RuCl2(p-异丙基苯)(PTA + H)]⁺）产生两个分子离子。对照实验表明，这两种电离途径之间的平衡受到用于注入的溶剂性质的强烈影响。四种分子离子的碰撞截面（CCS）准确反映了从膦配体的托尔曼空间参数（θ）推断出的空间体积变化。此外，密度泛函理论（DFT）计算结合基于气体动力学理论的模型（IMoS软件的轨迹方法）提供了可靠的CCS预测。与[Ru(III)Cl2(p-异丙基苯)(PTA)]⁺（μ = 7.18 D）相比，[RuCl2(p-异丙基苯)(PTA + H)]⁺（μ = 13.75 D）的偶极矩几乎高出两倍，这被认为是离子与诸如N2等可极化漂移气体之间的离子诱导偶极相互作用增加的原因。用He和CO2进行的进一步实验证实，增加缓冲气体的极化率改善了源自配合物的两种分子离子之间的分离。配合物的碎裂模式由CID确定。记录的源自化合物的分子离子在50%前体离子解离时的碰撞电压序列（V50）与基于膦配体供体强度的简单电子考虑结果高度一致。因此，用于确定气相中离子物种形状和稳定性的CCS和V50参数与有机金属化学家在凝聚相中常用的托尔曼空间和电子参数（θ和TEP）互补。
