Electronegativity effect on bond angles

As discussed earlier, the electronegativity effect causes not only a shortening of bonds, but also a deformation of bond angles, some getting smaller and some getting larger. The following discussion can best be understood with reference to Structure 2  

In the figure is shown a partial structure of propyl fluoride. As we increase the p character in the CF bond from carbon (relative to what it was in the corresponding hydrocarbon), the front-side angles indicated by the arrows, FCIH and FCIC, all tend to get smaller (toward 90°). The backside angles at Cl (those not mentioned in the previous sentence) tend to get correspondingly larger. This is the a-electronegativity effect 

Multiple substituents will presumably cause multiple effects, but they will also be diminished as successive ones are added, as was previously discussed for bond lengths. Some studies have been carried out along these lines, although not in very great detail. But everything so far learned seems consistent with what one anticipates from the above discussion. 

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