Browsing by Author "Mohammed Aichi"

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    BASICITY AND NUCLEOPHILICITY EFFECT IN CHARGE TRANSFER OF ALH3-BASE ADDUCTS: THEORETICAL APPROACH
    (Mohammed Aichi, 2023) Mohammed Aichi
    This study permits to explore the interactions involved in Lewis acid (AlH3) and Lewis bases: CO; H2O; NH3; PH3; PC13; H2S; CN–; OH–; O2–2; F–; N(CH3)3; N2; N2H4; N2H2; C5H5N; C6H5-NH2. By means of DFT theory calculations with B3LYP functional using 6-31G(d,p) basis set and in order to check the effects of both the donor and the acceptor in the establishment of the different adducts we focused mainly on the calculation of the energetic gap ∆EHOMO-LUMO, Gibbs energies ∆G, the angle (θ) in AlH3-base and the interaction energy values Einter. The several parameters of the reactivity (electrophilicity index (ω), nucleophilicity (N), chemical potential (μ), hardness (η), and polarizability (α)) are also calculated to define the weak interaction as well as to distinguish between the nucleophilicity and basicity of different Lewis bases. The results showed that the electronic charge transfer is estimated to be important in the systems where the interaction is established between Al and anionic bases, and the electron donor power is predictable for O–2, F–, OH–, and CN–. The pseudo-tetrahedral adduct arrangements depend on the parameter geometries (bond length interaction and θ angle) and Gibbs energies ∆G characterizing the main stability.
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    THEORETICAL STUDY OF PENTAVALENT HALOSILICONATES: STRUCTURE AND CHARGE DELOCALIZATION
    (Mohammed Aichi, 2021) Mohammed Aichi
    This study is performed to detect the pentavalent silicon center in the structure of pentavalent-halosiliconate R–O–Si(CH3)3X– and halotrimethylsilyloxyfurane structures (X–TMSOF), (X = F–; Cl–; Br–) and (R = CH3–; CH2–CH3; –CH(CH3)2; –CH=CH2; C6H5–). DFT calculations at the B3LYP/6-31G(d) level are caried out to understand their structures and charge delocalization. These intermediates are obtained by attacking the silicon center in trimethyl-alkoxysilanes and trimethyl-silyloxyfurane with halogen ions X–. The results obtained show that the attack by F– generates more stable structures because of the Si–F bond strong. In the case of Br– and Cl–, the structure of intermediates appears as an interaction between the ions and the silicon center. NBO analysis shows that one of F– lone pairs takes part in the Si–F bond formation. However, the lone pairs of Br– and Cl– do not contribute to generate a real bonding. DOI: 10.1134/S0022476621060020