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** Bond angle by theoretical calculation **

** Bond angles at bridging oxygens calculation **

** Bond angles dependence of calculated energies **

Values for the calculated bond angles in NH3 and H2O are shown in Table 3.21. There is quite reasonable agreement at the Hartree- [Pg.202]

Figure 7 Plot of calculated bond angles (deg) for XM(NH)3 versus |

Table 1 Observed and calculated bond angles in some halides and hydrides of oxygen |

Wyberg, in his modified CNDO/2 method 30>, calculated bond angles which are in good agreement with experiment. Del Bene and Jaffe 31> in their modified CNDO/2 method, however, were unable to reproduce satisfactory bond angles. [Pg.68]

Regarding the first of these factors, comparison of CISD-calculated bond angles in NH2 (102.6°) and CH3 (120.0°) indicates that the N-H bonds in NH2 have less 2s character than the C-H bonds in CH3.77 Such a difference, however, was found to account for no more than a quarter of the ca. 18 kcal/mol difference between the BDEs in Table 5 for R=R =H.77 [Pg.238]

Minimization of electrostatic interactions as defined by the various parameters described above, was done in order to calculate bond angles in halomethanes, -silanes and -germanes, as well as one-centre compounds that contain lone pairs and double bonds. The comparison with experimental values is such as to leave no doubt about the power of the VSEPR model. [Pg.187]

SH2, i.e. in cases where the central atom remains the same. On the other hand, the trends observed on the experimental bond angles, i.e. the increase as BX E molecules are charged to is also seen on the calculated values. It is only the molecule pair NEj and OF2 which an opposite change is observed in the calculated bond angles. However, the differences are tee small to warrant detailed considerations. [Pg.122]

X-ray crystal structure analyses yield information about the precise locations of the atoms contained within the crystal unit cell. From these locations, the geometry of the molecule under consideration can be derived by calculating bond angles, bond distances and torsion (dihedral) angles. [Pg.268]

Molecular mechanics (also known diS force-field calculations) is a method for the calculation of conformational geometries. It is used to calculate bond angles and distances, as well as total potential energies, for each conformation of a molecule. Steric enthalpy can be calculated as well. Molecular orbital calculations (p. 34) can also give such information, but molecular mechanics is generally easier, cheaper (requires less computer time), and/or more accurate. In MO calculations, positions of the nuclei of the atoms are assumed, and the wave equations take account only of [Pg.178]

Ab initio calculations on the three tautomeric forms of 2//-1,2,6-thiadiazine 1,1-dioxide reveals that for the 2H- (17) and 4H- (20) tautomers the planar conformers are less stable than the nonplanar boat conformers by 2.7 and 1.2 kcal moU, respectively. For the 3,5-dimethyl- derivative there is reasonable agreement between the calculated bond angles and those obtained by x-ray crystallographic measurements <90JP0470>. In contrast, for the fully conjugated tautomer (18) theoretical calculations reveal that the planar form is the more stable and that aromatic character is to be [Pg.697]

** Bond angle by theoretical calculation **

** Bond angles at bridging oxygens calculation **

** Bond angles dependence of calculated energies **

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