Insight of the Structures and Properties on 2-Thioxanthine Complexes with One Hg^(2+)and Two Cl^-Ions:a Theoretical Investigation

The molecular structures of fifteen possible 2-thioxanthine（2TX） complexes with one Hg^2＋ and two Cl-ions were fully optimized using density functional theory B3PW91/6-311＋＋G^＊＊ method. The effective pseudo potential LANL2DZ basis set was used for metal Hg^2＋ion. The vibrational analysis was also carried out at the same level. The bond lengths, bond angles, zero point energies, Gibbs free energies, thermodynamic energies and relative energies of all the complexes were obtained. The NBO analysis for natural charge and the second order perturbation energy values was carried out for three stable complexes and the IR spectroscopy of the two complexes was assigned to the experimental data. The results show that the 2-thioxanthine complexes with one Hg^2＋ and two Cl^-ions were formed and the complexes resulting from the thione tautomer are more stable than that of the thiol ones. The order of three complexes with relative lower energy is 2TX（1,3,7）-Hg^2＋-2, 2 TX（1,3,7）-Hg^2＋-1 and 2 TX（1,3,9）-Hg^2＋. The calculated IR spectroscopy of the two complexes agreed with the experimental data.

Dynamic Response of Tunnel Structures in Inhomogeneous Medium Under SHWave:Shear Modulus in Quadratic Functional Form

The task of thiswork is to study the scattering of SHwaves by homogeneous tunnel structures in an unbounded inhomogeneous medium.The shear modulus is assumed to be a function of coordinates(x,y).Atwo-dimensional scattering model is established.Selecting different inhomogeneous parameters,the medium has different properties,expressed as a rigid variation.The stress concentration phenomenon of the structure is analyzed for material design.Based on the complex function theory,the expressions of wave field in the tunnel are derived.The stress concentration phenomenon on the tunnel is discussed with numerical examples.The distribution of dynamic stress concentration factor on the inner and outer boundaries is analyzed under different influencing factors.Finally,it is found that the distribution of dynamic stress concentration factor is significantly affected by the inhomogeneous parameters and reference wave numbers of the medium.

Comparative DFT Study of [Mg(CHZ)_3](ClO_4)_2 and [Mg(CHZ)_3](NO_3)_2(CHZ=Carbohydrazide)

The molecular geometry,electronic structure,thermochemistry and infrared spectra of [Mg（CHZ）3]（ClO4）2 and [Mg（CHZ）3]（NO3）2 were comparatively studied using the Heyd-Scuseria-Ernzerhof（HSE） screened hybrid density functional with 6-31G＊＊ basis set.The experimental results show that the complexes have six-coordinated octahedron feature,and the metal-ligand interactions are predominantly ionic in nature.The calculated heats of formation predict that [Mg（CHZ）3]（NO3）2 is more stable than [Mg（CHZ）3]（ClO4）2.Detailed NBO analyses indicate that the ligand-anion interaction plays an important role in the stability for these two energetic complexes.Moreover,the stretching vibration frequencies of N-H bonds shift to lower wave number compared to the free CHZ ligand,which are caused by the delocalizations from N-H bond orbital to lone-pair electron antibond orbital of magnesium.

Mechanism of trifluoromethylation reactions with well-defined NHC copper trifluoromethyl complexes and iodobenzene:A computational exploration

Computational calculation was performed to investigate the mechanism of trifluoromethylation reactions of iodobenzene with well-defined N-heterocyclic carbene （NHC）-supported Cu~ trifiuor- omethyl complexes. Four proposed reaction pathways, namely cr-bond metathesis （BM）, concerted oxidative addition-reductive elimination （OARE）, iodine atom transfer （IAT） and single-electron transfer （SET）, have been computed by density functional theory （DFT）. The result indicated that the concerted OARE mechanism is favored among the four reaction pathways, suggesting the trifluoromethylation may occur via concerted OARE mechanism involving Ar-X oxidative addition to the Cu（1） center as the rate determining step.

A MATHEMATICAL MODEL OF THE FLOW FROM THE OUTLET IN DAMS

WT5”BZ]On the basis of the theory of complex functions the authors derive the boundary integral equations for the flow discharging from an outlet in a dam in an auxiliary plane. Assuming that the integral variables are constants in small integral intervals, one can directly integrate the boundary integral equations. With the use of the boundary stream coordinates, the boundary integral equations in the physical plane are obtained. Therefore the angle of the solid boundaries is a known function of stream coordinates in the physical plane instead of an unknown function in the complex potential plane or auxiliary plane. As a result we avoid the difficulty for seeking the mapping function which conformally maps the physical plane onto the complex potential or auxiliary plane. A synchronous iterative method for the flow rate and the flow pattern is presented. The flow rate, the pressure distributions at the solid walls and the profiles of the free jet are calculated. The numerical results are in excellent agreement with the experimental results.[WT5”HZ]