Georgiy V. Girichev

Compounds of metals with organic moieties cover the widest classes of chemical substances, with various applications in the chemical industry, catalysis, microelectronics, sensors, medicine, pharmacology, etc

The dialectic of the development of science is expressed in the fact that today’s experiments must give way to tomorrow’s theory, which makes these experiments unnecessary, but which, in turn, must give way to a new, more accurate experiment the day after tomorrow, and so on along the path of progress

A study of saturated vapor over the pyridine N-oxide-boron trifluoride (PyO-BF₃) adduct was carried out at T = 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-BF₃ adduct. Using the DFT/M06-2X/aug-cc-pVTZ method, geometric optimization of the molecular ion [PyO-BF₃]⁺ was carried out, which showed its intrinsic instability and dissociation into a [PyO]⁺ cation and a BF₃ 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-BF₃ and the previously studied BF₃ 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.

Using quantum chemical calculation data obtained by the DFT method with the B3PW91/TZVP and M062X/def2TZVP theory levels, the possibility of the existence of four Be(II) coordination compounds, each of which contains in the inner coordination sphere and the double deprotonated forms of subporphyrazine (H₂SP), mono[benzo]subporphyrazine (H₂MBSP), di[benzo]subporphyrazine (H₂DBSP), and tri[benzo]subporphyrazine (subphthalocyanine) (H₂TBSP) with a ratio Be(II) ion/ligand = 1:1, were examined Selected geometric parameters of the molecular structures of these (666)macrotricyclic complexes with closed contours are given; it was noted that BeN3 chelate nodes have a trigonal–pyramidal structure and exhibit a very significant (almost 30°) deviation from coplanarity; however, all three 6-membered metal-chelate and three 5-membered non-chelate rings in each of these compounds are practically planar and deviate from coplanarity by no more than 2.5°. The bond angles between two nitrogen atoms and a Be atom are equal to 60° (in the [BeSP] and [BeTBSP]) or less by no more than 0.5° (in the [BeMBSP] and [BeDBSP]). The presence of annulated benzo groups has little effect on the parameters of the molecular structures of these complexes. Good agreement between the structural data obtained using the above two versions of the DFT method was noticed. NBO analysis data for these complexes are presented; it was noted that, according to both DFT methods used, the ground state of the each of complexes under study is a spin singlet. Standard thermodynamic parameters of formation (standard enthalpy Δ_fH⁰, entropy S⁰, and Gibbs free energy Δ_fG⁰) for the above-mentioned macrocyclic compounds were calculated.

Synchronous electron diffraction/mass spectrometry was used to study the composition and structure of molecular forms existing in a saturated vapor of cobalt(II) oxopivalate at T = 410 K. It was found that monomeric complexes Co₄O(piv)₆ dominate in the vapor. The complex geometry possesses the C₃ symmetry with bond lengths Co–O_c = 1.975(5) Å and Co–O = 1.963(5) Å, as well as bond angles O_c–Co–O = 111.8(3)°, Co–O_c–Co = 110.4(6)°, O–Co–O = 107.1(3)° in the central O_cCo₄ fragment and four O_cCoO₃ fragments. The presence of an open 3d shell for each Co atom leads to the possibility of the existence of electronic states of the Co₄O(piv)₆ complex with Multiplicities 1, 3, 5, 7, 9, 11, and 13. For them, the CASSCF and XMCQDPT2 calculations predict similar energies, identical shapes of active orbitals, and geometric parameters, the difference between which is comparable with the error of determination by the electron diffraction experiment. QTAIM and NBO analysis show that the Co–O_c and Co–O bonds can be attributed to ionic (or coordination) bonds with a significant contribution of the covalent component. The high volatility and simple vapor composition make it possible to recommend cobalt (II) oxopivalate as precursors in the preparation of oxide films or coatings in the CVD technologies. The features of the electronic and geometric structure of the Co₄O(piv)₆ complex allows for the conclude that only a very small change in energy is required for the transition from antiferromagnetically to ferromagnetically coupled Co atoms.

Кратко рассмотрены структурные, спектроскопические и термодинамические исследования, выполненные в научных лабораториях кафедры физики Ивановского государственного химико-технологического университета в последние 5 -10 лет. Для цитирования: Гиричев Г.В., Гиричева Н.И., Кудин Л.С., Соломоник В.Г., Белова Н.В., Бутман М.Ф., Вьялкин Д.А., Дунаев А.М., Ерошин А.В., Жабанов Ю.А., Краснов А.В., Кузьмина Л.Е., Кузьмин И.А., Курочкин И.Ю., Моталов В.Б., Наваркин И.С., Пименов О.А., Погонин А.Е., Слизнев В.В., Смирнов А.Н., Твердова Н.В., Шлыков С.А. Процессы парообразования и точная молекулярная структура ряда органических и неорганических соединений, перспективных для использования в технологиях с участием газовой фазы. Изв. вузов. Химия и хим. технология. 2023. Т. 66. Вып. 7. С. 11-30. DOI: 10.6060/ivkkt.20236607.6850j. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Based on the data of the gas electron diffraction/mass spectrometry (GED/MS) experiment, the composition of the vapor over rhenium tetrafluoride at T = 471 K was established, and it was found that species of the Re₂F₈ is present in the gas phase. The geometric structure of the Re₂F₈ molecule corresponding to D_4h symmetry was found, and the following geometric parameters of the r_h1 configuration were determined: r_h1(Re-Re) = 2.264(5) Å, r_h1(Re-F) = 1.846(4) Å, α(Re-Re-F) = 99.7(0.2)°, φ(F-Re-Re-F) = 2.4 (3.6)°. Calculations by the self-consistent field in full active space approximation showed that for Re₂F₈, the wave function of the ¹A_1g ground electronic state can be described by the single closed-shell determinant. For that reason, the DFT method was used for a structural study of Re₂X₈ molecules. The description of the nature of the Re-Re bond was performed in the framework of Atom in Molecules and Natural Bond Orbital analysis. The difference in the experimental values of r(Re-Re) in the free Re₂F₈ molecule and the [Re₂F₈]²⁻ dianion in the crystal corresponds to the concept of a triple σ²π⁴ (Re^IV-Re^IV) bond and a quadruple σ²π⁴δ² (Re^III-Re^III) bond, respectively, which are formed between rhenium atoms due to the interaction of d-atomic orbitals. The enthalpy of dissociation of the Re₂F₈ molecular form in two monomers ReF₄ (Δ_dissH°(298) = 109.9 kcal/mol) and the bond energies E(Re-Re) and E(Re-X) in the series Re₂F₈→Re₂Cl₈→Re₂Br₈ molecules were estimated. It is shown that the Re-Re bond energy weakly depends on the nature of the halogen, while the symmetry of the Re₂Br₈ (D_4d) geometric configuration differs from the symmetry of the Re₂F₈ and Re₂Cl₈ (D_4h) molecules.

A comprehensive study of saturated vapors of 4-n-propyloxybenzoic acid (POBA) by gas electron diffraction (GED) and mass spectrometric (MS) methods supplemented by quantum chemical (QC) calculations was carried out for the first time. An attempt was made to detect dimeric forms of the acid in the gaseous state. It has been established that at the temperature of GED experiment, vapor over a solid sample contains up to 20 mol.% of cyclic dimers with two O-H...O hydrogen bonds. The main geometrical parameters of gaseous monomers and dimers of POBA are obtained. The distance r(O…O) = 2.574(12) Å in the cyclic fragment of the gaseous dimer is close to that in the crystal structure (2.611 Å). In the mass spectrum of the POBA recorded the ions of low intensity with a mass exceeding the molecular mass of the monomer were detected. The presence of ions, whose elemental composition corresponds to the dissociative ionization of the dimer, confirms the results of the GED experiment on the presence of POBA dimers in the gas state. The results of GED studies of acetic acid, benzoic acid, and POBA were compared. It is shown that the COOH fragment saves its geometric structure in monomers, as well as the COOH...HOOC fragment with two hydrogen bonds in dimers of different acids. The intermolecular interaction energy in considered acid dimers was estimated using QC calculations (B97D/6-311++G **). The significant value of last (>84 kJ/mol) is the reason for the noticeable presence of dimers in the gas phase.