Gas‐phase interactions between Ba²⁺ and deprotonated cytosine (C_(−H)) were studied in [C_(−H)Ba]⁺ and [C_(−H)BaC]⁺ complexes by IRMPD spectroscopy coupled to tandem mass‐spectrometry in combination with DFT calculations. For the [C_(−H)BaC]⁺ complex only one [C_(−H)KAN1O−Ba‐C_anti]⁺ isomer was found, although the presence of another structure cannot be excluded. This isomer features a central tetracoordinated Ba²⁺ that simultaneously interacts with keto‐amino [C_(−H)]⁻ deprotonated on N1 and neutral keto‐amino C. Both moieties are in different planes as a consequence of an additional NH…O=C hydrogen bond between C and [C_(−H)]⁻. A sequential IRMPD dynamics is observed in this complex. For the [C_(−H)Ba]⁺ complex produced by electrospray ionization two isomers ([C_(−H)KAN1OBa]⁺ and [C_(−H)KAN3OBa]⁺) were identified, in which Ba²⁺ interacts simultaneously with the C=O group and the N1 or N3 atom of the keto‐amino [C_(−H)]⁻, respectively. A comparison with the related [C_(−H)Pb]⁺ complex (J. Y. Salpin et al., Chem. Phys. Chem. 2014, 15, 2959–2971) is also presented.

中文翻译：

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关于去质子化胞嘧啶（CH）和Ba2 +之间的相互作用：红外多光子光谱学和动力学。

通过串联质谱结合IRMPD光谱研究了[C _（-H） Ba] ⁺和[C _（-H） BaC ] ⁺络合物中Ba ²⁺与去质子化胞嘧啶（C _（-H））之间的气相相互作用。结合DFT计算。对于[C _（-H） BAC] ⁺络合物只有一个[C _（-H） KAN1O-BAC_抗] ⁺异构体被发现，尽管其他结构的存在不能被排除。该异构体的特征是中央四配位Ba ²⁺可以同时与酮氨基[C _（-H） ] ^-相互作用在N1和中性酮氨基C上去质子化。由于C和[C _（-H） ] ^-之间存在额外的NH…O = C氢键，两个部分都位于不同的平面上。在该复合物中观察到了连续的IRMPD动力学。对于通过电喷雾电离产生的[C _（-H） Ba] ⁺络合物，鉴定了两个异构体（[C _（-H） KAN1OBa] ⁺和[C _（-H） KAN3OBa] ⁺），其中Ba ²⁺与C = O基团和酮氨基[C _（-H） ] ^-的N1或N3原子。与相关[C _（-H） Pb] ^+的比较络合物（J. Y. Salpin。等，化学物理。化学。2014，15，2959年至2971年）也呈现。