View source for Generalized Kac–Moody algebra

[[Image:AX3E0-3D-balls.png|thumb|left|200px|Idealized structure of a compound with trigonal planar coordination geometry.]]
[[Image:Boron-trifluoride-3D-vdW.png|thumb|right|200px|Structure of [[boron trifluoride]], an example of a molecule with trigonal planar geometry.]]
In [[chemistry]], '''trigonal planar''' is a [[molecular geometry]] model with one atom at the center and three atoms at the corners of a triangle, called peripheral atoms, all in one plane.<ref name=March>Jerry March Advanced Organic Chemistry 3rd Ed.</ref> In an ideal trigonal planar species, all three ligands are identical and all bond angles are 120° or <math style="height: 1.6em;">\frac{2\pi}{3}</math> radians.  Such species belong to the [[point group]] D<sub>3h</sub>.  Molecules where the three ligands are not identical, such as [[formaldehyde|H<sub>2</sub>CO]], deviate from this idealized geometry.  Examples of [[molecule]]s with trigonal planar geometry include [[boron trifluoride]] (BF<sub>3</sub>), [[formaldehyde]] (H<sub>2</sub>CO), [[phosgene]] (COCl<sub>2</sub>), and [[sulfur trioxide]] (SO<sub>3</sub>).  Some ions with trigonal planar geometry include [[nitrate]] (NO<sub>3</sub><sup>−</sup>), [[carbonate]] ion (CO<sub>3</sub><sup>2−</sup>), and [[guanidine|guanidinium]] C(NH<sub>2</sub>)<sub>3</sub><sup>+</sup>.  In organic chemistry, planar, three-connected carbon centers that are trigonal planar are often described as having [[orbital hybridisation|sp<sup>2</sup> hybridization]].<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref><ref>G. L. Miessler and D. A. Tarr “Inorganic Chemistry” 3rd Ed, Pearson/Prentice Hall publisher, ISBN 0-13-035471-6.</ref>

[[Nitrogen inversion]] is the distortion of pyramidal [[amine]]s through a transition state that is trigonal planar.

'''Pyramidalization''' is a distortion of this molecular shape towards a [[tetrahedral molecular geometry]]. One way to observe this distortion is in [[pyramidal alkene]]s.<ref name=March />

==See also==
*[[AXE method]]
*[[Molecular geometry]]
*[[VSEPR theory]]

==References==
<references/>

==External links==
*[http://www.3dchem.com/ 3D Chem Chemistry, Structures, and 3D Molecules]
*[http://www.iumsc.indiana.edu/ Indiana University Molecular Structure Center]
*[http://www.phys.ncl.ac.uk/staff/njpg/symmetry/Molecules_l3d.html Point Group Symmetry Interactive Examples]
*[http://chemlab.truman.edu/CHEM121Labs/MolecularModeling1.htm Molecular Modeling]
*[http://intro.chem.okstate.edu/1314F97/Chapter9/3BP.html Animated Trigonal Planar Visual]

{{MolecularGeometry}}

[[Category:Stereochemistry]]
[[Category:Molecular geometry]]