Interbond angle

As shown in Figure 1 for BP and DMBA, measured C-C bond lengths, interbond angles and torsion are variable around these values. 

Figure 1. (a) Bond lengths, (b) interbond angles and (c) torsion... 

Figure 9. Averaged geometry of an epoxide showing bond distances and interbond angles. Values in parentheses are estimated standard deviations of these average values.

Fig. 1. Bond lengths and interbond angles of Paludrine (85). (Reproduced by kind permission of the author, and of the Chemical Society, London)...

In Chapter 10, it is shown that by using symmetry considerations alone we may predict the number of vibrational fundamentals, their activities in the infrared and Raman spectra, and the way in which the various bonds and interbond angles contribute to them for any molecule possessing some symmetry. The actual magnitudes of the frequencies depend on the interatomic forces in the molecule, and these cannot be predicted from symmetry properties. However, the technique of using symmetry restrictions to set up the equations required in calculations in their most amenable form (the F-G matrix method) is presented in detail. 

Qualitative ways of analyzing a problem in molecular vibrations, that is, methods for determining the number of normal modes of each symmetry type which will arise in the molecule as a whole and in each set of equivalent internal coordinates, have been developed. There is also the quantitative problem of how the frequencies of these vibrations, which can be obtained by experiment, are related to the masses of the atoms, the bond angles and bond lengths, and most particularly the force constants of the individual bonds and interbond angles. In this section we shall show how to set up the equations which express these relationships, making maximum use of symmetry to simplify the task at every stage. 

Similarly, we can use the six interbond angles to generate a representation, obtaining rHCH, which reduces thus ... 

Bond distances (a-e) in A and interbond angles (a-e) in degrees numbers in parentheses are the estimated standard deviations in the least significant digit. Data taken from Reference 194. 

Many AX2E2 type molecules, such as Se(CH3)2, SeCl2, Te(CH3)2, and TeBr2, all exhibit a bent configuration, in which repulsion of lone pairs makes the interbond angles smaller than the ideal tetrahedral angle ... 

Force constants, interbond angle and solid state spectrum of disilox-ane. Spectrochim. Acta 13, 38—42 (1958). 

---