Trigonal bipyramidal molecular geometry

Phosphorus pentachloride has trigonal bipyramidal molecular geometry.

Trigonal bipyramidal molecular geometry is a type of molecular geometry. Molecules with this geometry have a central atom surrounded by five other atoms. Two of the outer atoms make a straight line through the center atom, and the other three make a (roughly) equilateral triangle surrounding it. The triangle is perpendicular to the line.

Triangular bipyramidal molecules where the central atom is a main-group element are considered hypervalent.

Several geometries with fewer atoms are related to trigonal bipyramidal molecular geometry. They are shaped like trigonal bipyramids with one or more atoms replaced with lone pairs:

• Replacing one atom with a lone pair gives seesaw molecular geometry, AX₄E
• Replacing two atoms with lone pairs gives T-shaped molecular geometry, AX₃E₂
• Replacing three atoms with lone pairs gives a type of linear molecular geometry, AX₂E₃