Experimental bond angles

C1U-UUU4.me gaseous compound stibine, HDJrl, nas experimental bond angles ot (Jive a complete description of the bonding in stibine, including a ball-and-stick sketch that shows the shape of the molecule. 

This descripiion of the bonding orbitals is only an approximation the experimental bond angle is 116°. bEquauon 3.16. 

Table 6.4 Comparison of experimental bond angles (°) with those calculated with wavefunction-based electronic structure methods.

Table 1 Experimental and Calculated Bond Distances and Experimental Bond Angles in Tris(4-methoxyphenyl)-l,2,3-triazine3...

Bond Experimental PPPb SPOb Experimental bond angle (°) ... 

Experimental bond angles AMB, the corresponding R(A/B) values and the length of the trans metal-ligand bond relative to the length of the cis metal—ligand bonds, (M—F)/(M—B), for a selection of compounds, are collected in Table 9. 

Experimental Bond Angle and Bond Length Data for Z/E-2-Butene (17/15) and Z/ -l,2-di-lerr-Butylethene (255a/256) ... 

The hybridization assigned to the central atom is based on the experimental bond angle. For example, if the experimental bond angle is about 109° we say that the central atom is 5/ -hybridized. Another example, if the experimental bond angle is about 180° we say that the central atom is 5/7-hybridized. 

For N3 , there are two domains, forcing a linear electron geometry. As both domains are bonding, the molecular geometry will also be linear and the bond angle will be 180. The experimental bond angle is 180 with a bond length of I 18 pm, consistent with that of a typical N=N double bond. 

The experimental bond angle in NH3 is 107.2°. Application of Equation (10.8) yields 23% s-character and 77% p-character in each of the three N-H single bonds. Because 3(23.3%) = 69%, the lone pair in ammonia has approximately 31% s-character. As a result, the lone pair in NH3 will have slightly greater s-character than will the lone pair in H2O. The greater basicity of NH3 relative to H2O can at least in part be attributed to the fact that the lone pair in ammonia will have a greater amount of overlap with the I s-orbital on a proton than will a lone pair on water. 

Example 10-2. Rationalize the following experimental bond angles using Bent s rule. 

The most important geometrical parameters of the optimized structures of the four compounds examined are compared in Tables 1 and 2 with the available experimental geometries of similar compounds [31]. For I and II all the calculated bond lengths are close to their experimental values and, taking into account that the reference experimental compounds bear bulky substituents, there is a good agreement also between the calculated and the experimental bond angles. 

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. 

Self-test 10.2) Give a VB description of NH3, and predict the bond angle of the molecule on the basis of this description. The experimental bond angle is 107°. 

The predicted bond angle is 90°, which is in poor agreement with the experimental bond angle (104°). 

Our simple descriptions of the NH3 and H2O molecules do not exactly correspond to the experimental bond angles. Better descriptions can be constructed by carrying out calculations using LCAOMOs that are linear combinations of all atomic orbitals in the basis set. Hybrid orbitals are then not needed and the canonical molecular orbitals can extend over the entire molecule prior to energy localization. Improvements can also be obtained by using a larger basis set. 

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