Alkene out-of-plane bending vibrations

The out-of-plane C-H bend of an alkene is a good way to determine how the alkene is substituted:

Monosubstituted (Vinyl): These give two strong bands near 990 and 910 respectively. The overtone of the 910 band usually appears at 1820 - which helps to confirm a vinyl group. The 910 band can shift as low as 810 if the substituent donates electrons via resonance (Cl, F, OR) and can shift as high as 960 if the substituent withdraws electrons by resonance (C=O, CN). The use of oop bands to confirm a vinyl group is considered very reliable.

Cis and trans: Cis has a strong peak at at 700, trans at 970. This can be valuable in assigning stereochemistry.

1,1-Disubstituted (Geminal): A strong band around 890, if electron withdrawing or donating groups are attached to the double bond, shifts similar to Vinyl alkenes occur.

Trisubstituted: One medium band near 815

Tetrasubstituted: No absorption, due to the absence of a C=C-H bond. In addition, the C=C stretch around 1670 is weak or absent for highly-substituted double bonds.