trigonal planar arrangement

Trigonal planar arrangement describes a molecular geometry where one central atom is bonded to three other atoms, all lying in the same plane. These three peripheral atoms are positioned at the corners of an equilateral triangle around the central atom.

Molecules like boron trifluoride (BF₃), sulfur trioxide (SO₃), formaldehyde (H₂CO), and phosgene (COCl₂) exhibit this geometry. This shape arises from the repulsion between electron pairs in the valence shell of the central atom, which arrange themselves to minimize these repulsions, leading to a planar configuration. This arrangement is distinct from a triangular ring structure, such as in cyclopropane, where bond angles can cause significant strain.12