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Within density functional theory the structure of an inclusion compound based on Ni(II) dimethylglyoxymate and the macrocyclic cucurbit[8]uril nanocavitand is investigated and the thermodynamic parameters of its formation are estimated. Based on the results obtained a prediction is made about the principal possibility of the synthesis of this inclusion compound.

Using quantum chemical calculations, we report structures, energetics, natural bond analysis, aromaticity and ¹⁴N NQR parameters of the irdidapyridine isomers. The mpw1pw91, PBEPBE and PBE1PBE calculations indicate the most stability for meta-isomer. Global electrophilicity index shows that iridapyridines are stronger electrophile rather than pyridine. Local reactivity descriptors as Fukui functions, local softnesses and electrophilicity indices analyses are performed to find out the reactive sites within molecules. Nucleus-independent chemical shift (NICS) has been evaluated to understand the aromaticity. Also, changes in ¹⁴N NQR parameters of the molecules are studied.

The structures and properties of asymmetric heterocycles (HBrBN₃)_n (n = 1-4) are systematically studied at the B3LYP/6-31G* level. The molecules (HBrBN₃) _n (n = 2-4) have the core structures of a 2n-membered ring with alternating boron and a-nitrogen atoms. The relationships between geometrical parameters and oligomerization degree n are discussed. The calculated IR spectra have four main characteristic regions. Trends in thermodynamic properties with temperature and oligomerization degree n are discussed. Thermodynamic analysis of the gas-phase oligomerizations shows that formation of the most stable heterocycles (HBrBN₃)_n (n = 2-4) is enthalpy driven in the range of 200-800 K.

The structure, ¹⁴N NQR parameters, electronic spectra, and hyperplarizability of [Cr(CO)₅py] in seven different solvents were theoretically computed with MPW1PW91 method based on Polarizable Continuum Model (PCM). The substituent effects in para- substituted Cr(CO)₅-pyridine complexes have been evaluated. The results indicate that both polarity of solvents and the substituents have played a significant role on the structures and properties of complexes. The study also shows that the structural and solvent modification change the NLO properties.

Using MPW1PW91 quantum chemical calculations, we report structures, frontier orbital analysis, natural bond analysis, and aromaticity of the C₅H₅Ir(PH₃)₃ iridabenzene and XC₅H₄Ir(PH₃)₃para-substituted iridabenzenes. The substituent effects were estimated from the donor-acceptor interaction energies of the natural bond orbitals of substituent and iridabenzene frame. Nucleus-independent chemical shift (NICS) has been evaluated to understand the aromaticity. Time dependent density functional theory (TD-DFT) is used to calculate the energy, oscillatory strength and wavelength absorption maxima (l_max) of electronic transitions and their nature. Changes in hyperpolarizability of molecules are studied. Influence of solvent on the structure, frontier orbital energies, λ_max, and hyperpolarizability of C₅H₅Ir(PH₃)₃ iridabenzene has been studied.

Theoretical studies on the lanthanide and actinide triflate complexes M(OTf) _n where M = La, Ce, Gd, Yb, Lu, Th, U, Np, Pu, Am, Cm, Bk, and No; n = 3 and 4, are carried out using functional density theory (DFT). The study of An(OTf)₃ complexes showed that the three OTf groups are bidentate, generating a trigonal prism (TP). Two limiting structures of TP are observed; the most distorted is the thorium triflate Th(OTf)₃ and the ideal one is U(OTf)₃. The highest population contribution of 5 d orbital compared to 5 f orbital in Th-O bond of Th(OTf)₃ explains the distortion. The intramolecular rearrangement of the OTf ligands in Ln(OTf)₃ generates two conformers. In Yb(OTf)₃, the pseudo-eclipsed and the staggered conformations are stable and can be isolated.

Two new compounds of fluorine: (C₂H₅)₄N[I₂F] and (C₂H₅)₄N[Br₂F] have been easily synthesized in a nearly quantitative by a direct reaction of (C₂H₅)₄NF, I₂ and Br₂. The products were isolated and characterized by elemental analysis and spectroscopic methods such as: Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). These compounds have been studied with the Scalar ZORA relativistic level of theory using the ADF program package. The molecular parameters, and vibrational spectra were calculated. The excitation energies were found by time-dependent perturbation density functional theory (TD-DFT). Molecule optimization, frequencies and excitation energies were calculated with standard Slatertype-orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all atoms. The FTIR, UV-Vis spectra and assignment of principal transitions and total density of state (TDOS) were extracted using the GaussSum 2.2 program. The comparison between experimental and calculated values shows that the experimental results correlate well with the predicted data.

Synthesis procedures for new coordination compounds of iron(II) with tris(pyrazol-1-yl)methane (HC(pz)₃), containing cluster anions in the outer sphere, of the composition [Fe{HC(pz)₃}₂][Mo₆Cl₁₄]×2H₂O (I), [Fe{HC(pz)₃}₂][Mo₆Br₁₄]×H₂O (II), and [Fe{HC(pz)₃}₂]₂[Re₆S₈(CN)₆]×2H₂O (III) are developed. The compounds are studied by static magnetic susceptibility, electronic, IR, and Mössbauer spectroscopic methods. The magnetochemical study shows that in the polycrystalline phases of all compounds the spin-crossover ¹ А ₁ Û ⁵ - ₂ is observed which is accompanied by thermochromism.

A new dinuclear Fe(III) complex, [Fe(5-MeOL1)(OH)_0.86(CH₃O)_0.14]₂×2(CH₃OH), [H₂-5-MeOL1 = N,N¢-bis(5-methoxy-2-hydroxybenzylidene)-2,2-dimethylpropane-1,3-diamine], 1 has been synthesized and characterized by single crystal structure analysis. The structure of 1 consists of two Fe(III) centers with one tetradentate schiff base ligand (N₂O₂) which are bridged by dihydroxo/dimethoxo groups to yield a Fe₂O₂ core. Complex 1 exhibits weak antiferromagnetic exchange interaction between Fe(III) ions with J = -0.21 cm^-1.

By employing trans -dicyano or pentacyanometalate as building block and using a bicompartimental Schiff-base based manganese(III) compound as assemble segment, two new cyanide-bridged heterometallic Fe(III)-Mn(III) complexes {[Mn(L)(H₂O)][Febpb(CN)₂]}×2CH₃OH (1) and {[Mn(L)(H₂O)]₂×[Fe(CN)₅NO]} (2) (bpb^2- = 1,2-bis(pyridine-2-carboxamido)benzenete, L = N,N¢-ethylene-bis(3-ethoxysalicylideneiminate) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis reveals binuclear FeMn and trinuclear FeMn₂ structure, respectively, in which the cyanide precursor acts as mono- or bidentate ligand to connect the Mn(III) Schiff-base unit(s). Furthermore, these two complexes are self-complementary through coordinated aqua ligands from one complex and the free O₄ compartments from the neighboring complex, giving dimeric and 1D single chain supramolecular structure. Investigation of the magnetic susceptibility of 1 reveals weak antiferromagnetic coupling between the adjacent Mn(III) ions. Based on the binuclear FeMn model, best fit of the magnetic susceptibilities of 1 leads to the magnetic coupling constants J = -1.37 cm^-1 and zJ ¢ = - 0.72 cm^-1 (1).