Search results for "Mulliken population analysis"
showing 8 items of 8 documents
A quantum-chemical study of the structure, vibrations and SiH bond properties of disilylamine, NH(SiH3)2.
2002
Quantum-chemical calculations at HF, MP2 and B3LYP levels with 6-31G* and 6-311G** basis sets are reported for disilylamine, NH(SiH3)2. The equilibrium structure is found to vary with both level and basis set, all but one of the structures exhibiting a small lack of planarity of the HNSi2 system. The barrier to inversion, however, is found to be very low, at most 38 cm(-1). Vibration frequencies and intensities are calculated. The frequencies are scaled, where possible, either using updated infrared data or with the aid of factors transferred from N(CH3)(SiH3)2. Unobserved frequencies due to the v(s)NSi2, deltaNSi2 and delta(perpendicular)NH modes are predicted near 610, 210 and 360 cm(-1),…
Diene-Containing Half-Sandwich MoIII Complexes as Ethylene Polymerization Catalysts: Experimental and Theoretical Studies
2001
International audience; Seventeen-electron compounds of Mo III having the general formula [(h 5-C 5 R 5)Mo(h 4-diene)X 2 ] (R H, Me; diene butadiene, iso-prene, or 2,3-dimethylbutadiene; X Cl, CH 3) are a new class of ethylene polymerization catalysts. The polyethy-lene obtained shows a bimodal distribution , the major weight fraction being characterized by very long (M around 10 6) and highly linear polymer chains. The newly prepared pentamethylcyclo-pentadienyl (Cp*) derivatives are more active than the cyclopentadienyl (Cp) derivatives, but much less active than previously investigated niobium III compounds having the same stoichiometry. On the other hand, the turnover frequency of the a…
Understanding the local reactivity in polar organic reactions through electrophilic and nucleophilic Parr functions
2013
[EN] Building upon our recent studies devoted to the bonding changes in polar reactions [RSC Advances, 2012, 2, 1334 and Org. Biomol. Chem., 2012, 10, 3841], we propose herein two new electrophilic, P-k(+), and nucleophilic, P-k(-), Parr functions based on the spin density distribution at the radical anion and at the radical cation of a neutral molecule. These local functions allow for the characterisation of the most electrophilic and nucleophilic centres of molecules, and for the establishment of the regio- and chemoselectivity in polar reactions. The proposed Parr functions are compared with both, the Parr-Yang Fukui functions [J. Am. Chem. Soc. 1984, 106, 4049] based on frontier molecul…
Validation of a constrained 2D slab model for water adsorption simulation on 1D periodic TiO2 nanotubes
2018
Abstract Solar light driven hydrogen evolution is one focus of modern materials research. Among the different emerging technologies, particular interest is devoted towards metal oxide photocatalysts in the form of various 1D nanostructures. Presently, the mismatch between regular structures that can be synthesized and the largest structures that are feasible for computer simulation is still very large. For example, an in-depth study of water adsorption on nanotube (NT) surfaces requires, in addition to DFT calculations, molecular dynamics simulations to take into account the disordered nature of the aqueous phase. To completely immerse even a very thin nanotube into an aqueous system requir…
A correlative IR, MS, 1H, 13C and 15N NMR and theoretical study of 4-arylthiazol-2(3H)-onesElectronic supplementary information (ESI) available: NMR …
2002
Sixteen 4-arylthiazol-2(3H)-ones (3) were synthesised by cyclisation of α-thiocyanatoacetophenones (1) in acid solution. They appear to prefer greatly the oxo tautomeric forms. In CCl4 solution an equilibrium between the free CO bond and a “dimeric” hydrogen-bonded form exists in which the latter predominates. Several IR and NMR (1H, 13C and 15N) spectral properties are shown to correlate with Hammett σ-values and/or atomic Mulliken charges and bond orders, the latter being estimated by PM3 or AM1 semiempirical methods. The electron-impact mass spectra were also recorded and the fragmentation mechanisms interpreted in terms of the energetics of the ionic species. In addition, the geometric …
Ferrocene-functionalized anilines as potent anticancer and antidiabetic agents: Synthesis, spectroscopic elucidation, and DFT calculations
2022
Abstract Ferrocene derivatives have attracted significant interest as potent biological agents and novel drug candidates. Hence, the present research work was focused on the synthesis and characterization of ferrocene-integrated anilines (FB1-FB4) through different spectroscopic techniques such as: FT-IR, multinuclear (1H and 13C) NMR, Raman, atomic absorption spectroscopy, elemental analysis, and single-crystal X-ray crystallography. The crystallographic analysis revealed a supramolecular structure mediated by secondary non-covalent interactions (π—H and π—π). These ferrocenyl derivatives demonstrated a quasi-reversible electrochemical behavior with one electron transfer from Fe(II) to Fe(…
Synthesis, crystal structure, DFT calculations, Hirshfeld surface, vibrational and optical properties of a novel hybrid non-centrosymmetric material …
2019
This present work undertakes the study of a novel organic–inorganic hybrid material, which has been obtained successfully by an acid-base reaction at room temperature and structurally studied by the single crystal X-ray diffraction method. (C10H15N2)2H2P2O7 crystallizes in the triclinic system with the non-centrosymmetric space group P1 with the following lattice parameters: a = 5.9159(2) Å, b = 13.8451(6) Å, c = 14.5973(5) Å, ? = 74.507(2)°, ? = 89.980(2)°, ? = 89.231(2)° with V = 1152.06(8) Å3 and Z = 2. The X-ray structural analysis supported by a detailed Hirshfeld 2D fingerprint plots has been performed to elucidate the different inter-contacts in the crystal structure mainly associate…
Intermetallic compounds of the heaviest elements: the electronic structure and bonding of dimers of element 112 and its homolog Hg
2002
Abstract Fully relativistic (four-component) density-functional calculations were performed for the element 112 dimers (112)X (X = Pd, Cu, Ag and Au) and those of its lighter homolog, Hg. A relatively small decrease of about 15–20 kJ/mol in bonding was found from the HgX to (112)X compounds. Respectively, the bond lengths were increased by 0.06 A on the average. The Mulliken population analysis has shown this effect to be a result of a decreasing contribution of the relativistically stabilized 7s-AO of element 112 to bonding. The following trend in the binding energies was predicted for (112)X as a function of X: Pd >Cu>Au>Ag, exactly as the trend obtained experimentally for adsorption of H…