Lebedev Ivan S, Belova Natalya V, Giricheva Nina I, Andreev Vladimir P, Sobolev Pavel S, Girichev Georgiy V
Ivanovo State University of Chemistry and Technology, Research Institute for Thermodynamics and Kinetics of Chemical Processes, Sheremetevsky Avenue, 7, Ivanovo 153000, Russia.
Ivanovo State University, Ermaka Street, 39, Ivanovo 153025, Russia.
Inorg Chem. 2024 Sep 2;63(35):16451-16460. doi: 10.1021/acs.inorgchem.4c02714. Epub 2024 Aug 19.
A study of saturated vapor over the pyridine -oxide-boron trifluoride (PyO-BF) adduct was carried out at = 448(5) K by a synchronous gas electron diffraction/mass spectrometry (GED/MS) experiment. Due to the absence of ions in the mass spectrum, indicating the presence of a structure with an O-B dative bond, several models of vapor composition were tested by the GED method. It was found that the dominant molecular form (up to 100%) in vapor is the PyO-BF adduct. Using the DFT/M06-2X/aug-cc-pVTZ method, geometric optimization of the molecular ion [PyO-BF] was carried out, which showed its intrinsic instability and dissociation into a [PyO] cation and a BF molecule. This study certainly demonstrates the significant advantage of the GED method to determine the qualitative and quantitative gas-phase composition of dative-bonded adducts and other noncovalent complexes as well, whereas the interpretation of mass spectra may be ambiguous due to the possible intrinsic instability of ions containing a dative bond. The nature of the O-B bond is discussed in terms of the natural bond orbitals (NBOs) and the quantum theory of atoms in molecules (QTAIM). A comparison of structural and energetic parameters for PyO-BF and the previously studied BF adducts allows the theoretical comprehension of the nature of the O-B bond to be extended and to explain the different thermal stabilities of these compounds.
通过同步气相电子衍射/质谱（GED/MS）实验，在448(5)K温度下对吡啶 - 氧化物 - 三氟化硼（PyO - BF）加合物上的饱和蒸汽进行了研究。由于质谱中没有离子，这表明存在具有O - B配位键的结构，因此通过GED方法测试了几种蒸汽组成模型。结果发现，蒸汽中占主导的分子形式（高达100%）是PyO - BF加合物。使用DFT/M06 - 2X/aug - cc - pVTZ方法对分子离子[PyO - BF]进行了几何优化，结果表明其固有不稳定性并分解为[PyO]阳离子和BF分子。这项研究无疑证明了GED方法在确定配位键加合物和其他非共价配合物的定性和定量气相组成方面具有显著优势，而由于含配位键离子可能存在的固有不稳定性，质谱的解释可能存在歧义。从自然键轨道（NBO）和分子中的原子量子理论（QTAIM）的角度讨论了O - B键的性质。对PyO - BF与先前研究的BF加合物的结构和能量参数进行比较，有助于扩展对O - B键性质的理论理解，并解释这些化合物不同的热稳定性。
