Deformation of bond angle

Cyclodecene is the smallest cycloalkene, which can accommodate a trans double bond without significant deformation of bond angles and/or dihedral angles. The strain energies and structures of smaller fraws-cycloalkenes have been the subjects of considerable research over the years. 

The data for anhydro-3-hydroxy[l,2,3]oxadiazolo[4,3-c][l,2,4]benzotriazin-10-ium hydroxide show the molecule to be essentially planar. The 0(2)—C(3) bond is relatively long, the exocyclic C(3)—O bond is almost of double bond character, and there is a marked deformation of bond angles around C(3). From the bond angles and bond lengths it appears that a ketene type of structure contributes substantially to the overall bonding situation <79JCS(P2)1751>. 

The deformation of bond angles from their normal value is also usually assumed to be controlled by a harmonic potential (Eqn. 49). 

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 ... 

The high axial elastic modulus of polyethylene and polyamide 6 is due to the fact that these polymers have a preferred conformation that is fully extended, i.e. all-trans. The elastic deformation is caused by the deformation of bond angles and by bond stretching, both showing high elastic constants. Isotactic polypropylene and polyoxymethylene crystallize in helical conformations and therefore exhibit a maximum stiffness which is only 20% of the maximum stiffness of the all-trans polymers. The elastic deformation of a helical chain involves, in addition to the deformation of bond angles and bond stretching, deformation by torsion about the G bonds. The latter... 

Provided that small deformations of bond angles and slight deviations of the internal rotation angles from A and A are allowed, this model presenting a statistical sequence of conformations maintains also the chain axis straight. 

Isomerization occurs with the highest rate when the geometrically most favorable six-membered cycle of the transition state is formed. This isomerization from position 1 to position 2 does not occur due, most likely, to great deformations of bond angles in the three-membered cycle of the transition state. 

Even at these small deformations the apparent Young s modulus E is a function of the rate of strain. This shows that E is not solely determined by the energy elastic deformation of bond angles, bond lengths, and intermolecular distances but also involves time-dependent displacements of atoms and small atom-groups. In the fol-... 

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