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The Middle East in general and the Persian Gulf sub-region in particular are becoming increasingly strategic for China. The sub-region is not only rich in natural resources, primarily energy, and to a large extent provides them to the dynamically developing Chinese economy, but also opens up access to main global maritime and land routes, as well as African and European markets. The study focuses on Chinas interaction with the Gulf Cooperation Council (GCC) countries in the field of energy, trade, and investment in the context of growing economic interdependence that elevates Beijings relations with the Arab countries of the sub-region to the level of strategic partnership. Thus, Chinas relations with this group of states go beyond purely economic interests and affect the strategic interests of Beijing, such as active promotion of the large-scale Belt and Road Initiative, which implies the intensification of Chinas policy in the Middle East. The methodological basis of the study is an interdisciplinary approach. The authors adhere to the neorealism, particularly the theory of the balance of power and regional security complexes, the principle according to which the foreign policy of a state is heavily dictated by the logic of the international system and the distribution of power among states. The power transit theory allows us to understand better the current role of China becoming a superpower in world politics. The research also applies such methods of historical science as chronological, genetic, systemic-structural, and comparative methods. The collection and processing of a significant layer of statistical data makes it possible to highlight the emergence of new powerful political actors in the Middle East.

The Knudsen effusion method with mass spectrometric control of the vapor composition was used to study the possibility of a congruent transition to the gas phase and to estimate the enthalpy of sublimation of metal-free tetrakis(1,2,5-thiadiazolo)porphyrazine and its nickel complex (H2TTDPz and NiTTDPz, respectively). The geometrical and electronic structure of H2TTDPz and NiTTDPz in ground and low-lying excited electronic states were determined by DFT calculations. The electronic structure of NiTTDPz was studied by the complete active space (CASSCF) method, following accounting dynamic correlation by multiconfigurational quasi-degenerate second-order perturbation theory (MCQDPT2). A geometrical structure of D2h and D4h symmetry was obtained for H2TTDPz and NiTTDPz, respectively. According to data obtained by the MCQDPT2 method, the nickel complex possesses the ground state 1A1g, and the wave function of the ground state has the form of a single determinant. Electronic absorption and vibrational (IR and resonance Raman) spectra of H2TTDPz and NiTTDPz were studied experimentally and simulated theoretically.

Electronic and geometric structures of Y, La and Lu complexes with porphyrazine (Pz) and tetrakis(1,2,5-thiadiazole)porphyrazine (TTDPz) were investigated by density functional theory (DFT) calculations and compared. The nature of the bonds between metal atoms and nitrogen atoms has been described using the analysis of the electron density distribution in the frame of Bader’s quantum theory of atoms in molecule (QTAIM). Simulation and interpretation of electronic spectra were performed with use of time-dependent density functional theory (TDDFT) calculations. Description of calculated IR spectra was carried out based on the analysis of the distribution of the potential energy of normal vibrations by natural vibrational coordinates.