The present work explores the structures of species formed by dehydrogenation of methane (CH₄) and perdeuterated methane (CD₄) by the 5d transition metal cation osmium (Os⁺). Using infrared multiple photon dissociation (IRMPD) action spectroscopy and density functional theory (DFT), the structures of the [Os,C,2H]⁺ and [Os,C,2D]⁺ products are explored. This study complements previous work on the related species formed by dehydrogenation of methane by four other 5d transition metal cations (M⁺ = Ta⁺, W⁺, Ir⁺, and Pt⁺). Osmium cations are formed in a laser ablation source, react with methane pulsed into a reaction channel downstream, and the resulting products spectroscopically characterized through photofragmentation using the Free-Electron Laser for IntraCavity Experiments (FELICE) in the 300–1800 cm⁻¹ range. Photofragmentation was monitored by the loss of H₂/D₂. Comparison of the experimental spectra and DFT calculated spectra leads to identification of the ground state carbyne hydride, HOsCH⁺ (²A′) as the species formed, as previously postulated theoretically. Further, a full description of the systematic spectroscopic shifts observed for deuterium labeling of these complexes, some of the smallest systems to be studied using IRMPD action spectroscopy, is achieved. A full rotational contour analysis explains the observed linewidths as well as the observation of doublet structures in several bands, consistent with previous observations for HIrCH⁺ (²A′).

Open image in new window

本工作探讨了由5d过渡金属阳离子（Os ⁺）脱氢甲烷（CH ₄）和全氘甲烷（CD ₄）形成的物质的结构。利用红外多光子离解（IRMPD）作用谱和密度泛函理论（DFT），研究了[Os，C，2H] ⁺和[Os，C，2D] ⁺产物的结构。这项研究是对以前通过其他四种5d过渡金属阳离子（M ⁺ = Ta ⁺，W ⁺，Ir ⁺和Pt ⁺）。a阳离子在激光烧蚀源中形成，与甲烷脉冲进入下游的反应通道中进行反应，然后使用用于腔内实验的自由电子激光（FELICE）在300-1800 cm ^-1范围内通过光碎化对所得产物进行光谱学表征。通过H ₂ / D ₂的损失来监测光碎裂。实验光谱和DFT计算光谱的比较可确定基态碳炔氢化物HOsCH ⁺（²如先前理论上假定的那样，A'）作为形成的物种。此外，获得了对这些复合物的氘标记观察到的系统光谱变化的完整描述，这是一些使用IRMPD作用光谱法研究的最小系统。完整的旋转轮廓分析说明了观察到的线宽以及在几个波段中的双峰结构的观察结果，这与以前对HIrCH ⁺（² A'）的观察结果一致。

在新窗口中打开图像