Square Planar
Definition and meaning of Square Planar in chemistry.
Square planar is a molecular geometry in which a central atom bonds to four atoms or ligands arranged in a square pattern within a single plane, with all bond angles at 90 degrees.
In more detail
In square planar geometry, the four bonded atoms occupy the corners of a square, with the central atom at the center, and all five atoms lying in the same plane. This geometry is particularly common among d8 transition metal complexes, such as those of Pt(II), Pd(II), and Ni(II), as well as in some main-group compounds like xenon tetrafluoride, XeF4. The square planar arrangement results from the interplay between ligand field effects and electronic configuration. This geometry is distinct from tetrahedral, which is three-dimensional and favored by d10 configurations.
Key facts
| Field | Inorganic Chemistry |
|---|---|
| Bond angles | 90 degrees (all atoms coplanar) |
| Typical electron configuration | d8 transition metals |
| Example compound | [Pt(NH3)4]2+ |
The complex ion [Pt(NH3)4]2+ (tetraammineplatinum(II)) is a classic square planar structure, where four ammonia ligands surround a central platinum(II) ion at the corners of a square.
Frequently asked questions
How does square planar geometry differ from tetrahedral?
Square planar has four atoms in a plane at 90 degree angles; tetrahedral has four atoms in three-dimensional space at 109.5 degree angles.
Why are d8 transition metals commonly square planar?
Crystal field theory predicts that d8 configurations stabilize square planar geometry at lower energy than tetrahedral.