The seesaw configuration in molecular geometry is a variation of the trigonal bipyramid configuration. The seesaw configuration occurs when there is a lone electron pair and four atoms are attached to the central atom. Sulfur tetrafluoride is an example of a trigonal bipyramid configuration exhibiting a seesaw structure.
The lone electron pair in the seesaw configuration compresses the angles of the atoms from 120 degrees to 102 degrees. The other bond angles are changed from 180 degrees to 187 degrees and 90 degrees to 86.5 degrees respectively.
Molecules with a seesaw configuration have a steric number of five. Molecules with four fluorides such as selenium tetrafluoride and tellurium tetrafluoride have a seesaw configuration too.