Calculated optimized geometries

Formation of the bicyclic lithiated intermediate 8 is considered to be a two-step process whereby the nitrogen atom of nitric oxide attaches to the Cl atom of propynyllithium. Addition of a second molecule of nitric oxide gives intermediate 8 that on reaction with water produces 5-methyl-l,2,3-oxatriazole 3-oxide 9 (Scheme 1). Calculated, optimized geometry and bond lengths for stmcture 9 together with calculated infrared (IR) and Raman spectra are reported <2005JOC5045>. 

The geometries of the ground states and of the first excited singlet and triplet states of 150 with X = SiH-, CH-, NH, O, PH and S were calculated by the Cl version of the semi-empirical SINDOl method167. We will discuss here only the silirenyl anion (150, X = SiH-) and compare the properties of this anion to those of the analogous cyclopropenyl anion (150, X = CH-). The calculated optimized geometries and bond orders for 150, X = SiH- and CH- are given in Table 15. 

The differences in the calculated geometrical parameters of the isolated molecules and the H-bonding dimers (which are models for the gas and solid phases) serve to emphasize the potential errors that may arise upon comparison of calculated geometrical parameters for isolated molecules with crystal structural data. It is significant that the calculated optimized geometries, themselves, change when intermolecular interactions that... 

Table 4. Calculated optimized geometry and flow parameters for example regenerators.

A consistent basis for the understanding of the interaction of cyclopropyl with the second-row substituents is provided by detailed theoretical study including 4-3IG basis set MO calculations. Optimized geometries and energies were obtained for the substituents Li, BeH, BH2, CH3, NH2, OH, and F, and stabilization energies (SE) were obtained relative to the corresponding i-PrX derivatives according to equation The results are shown in Table 10. 

Fig. 8 Calculated optimized geometries (front and side views) of the most stable con-formers of the IH- and 2H-tautomers of TAA. Reprinted with permission from C. Araujo-Andrade, i, Reva and R. Fausto, J. Chem. Phys., 2014, 140, 064306. Copyright 2014, AlP...

Figure 2 DFT calculated optimized geometries for 11 ligand-bridged transition metal complexes (VWN-Stoll potential) compared with related experimental synthetic systems. Metal-metal (rM-M) and metal-bridging ligand (rM-L) distances are given. The core complexes are (1) [Mn 20(OAc)2] + (2) [Mn Mn 0(OAc)2] (3) [Mn Mni 02(0Ac)]3+ (4) [Mni" 2(/ -0)3]"+ (5) [Fe 20(OAc)2]"+ (6) [Feii2(OH)(OAc)2]+ ...

Is SieHe a planar Deh molecule analogous to benzene The answer varies between the Deti structure (31) and the Dsd structure (32), depending on the theoretical method used . The calculated optimized geometries of the Z>6h and Dsa structures of SieHe at various theoretical levels are shown in Figure 5. While early HF/3-21G calculations found SieHe to have Den symmetry with r(Si-Si) equal to 2.220 this is not the case at higher levels of theory - -. Thus when d-functions are added to... 

In modem quantum chemistry packages, one can obtain moleculai basis set at the optimized geometry, in which the wave functions of the molecular basis are expanded in terms of a set of orthogonal Gaussian basis set. Therefore, we need to derive efficient fomiulas for calculating the above-mentioned matrix elements, between Gaussian functions of the first and second derivatives of the Coulomb potential ternis, especially the second derivative term that is not available in quantum chemistry packages. Section TV is devoted to the evaluation of these matrix elements. 

You can include geometric restraints—for interatomic distances, bond angles, and torsion angles—in any molecular dynamics calculation or geometry optim i/.ation. Here are some applications of restrain ts ... 

HyperChem always com putes the electron ic properties for the molecule as the last step of a geometry optimization or molecular dyn am ics calcu lation. However, if you would like to perform a configuration interaction calculation at the optimized geometry, an additional sin gle poin t calcu lation is requ ired with theCI option being turned on. 

An algorithm has been proposed for determining the reaction coordinate, transition structure, and optimized geometry all in a single calculation. The... 

In this example, the HOMO is plotted one Angstrom above the plane of the molecule. Since it is of n symmetry, it has a node in the plane of the molecule. It shows the site of electrophilic attack at the carbon adjacent to the oxygen atom. This is also the experimentally observed site. The orbital comes from an Extended Hiickel calculation of an MM-t optimized geometry. 

On the other hand, theoretical methods allow an insight into the structure of non-existent molecules like 2//-indazole (37) or the anion of indazole (38). INDO calculations have been performed by Palmer et al. on the anion of indazole (38) (75JCS(P1)1695). The optimized geometry obtained by them is shown in Figure 7. The N—N bond distance is longer in the... 

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