T-shaped molecular geometry

T-shaped molecular geometry
T-shaped molecular geometry
Examples	ClF3
Point group	C2v
Coordination number	3
Bond angle(s)	90° and 180°
μ (Polarity)	>0

Structure of chlorine trifluoride, an example of a compound with T-shaped coordination geometry.

In chemistry, T-shaped molecular geometry describes the structures of some molecules where a central atom has three ligands. Ordinarily, three-coordinated compounds adopt trigonal planar or pyramidal geometries. Examples of T-shaped molecules are the halogen trifluorides, such as ClF₃.^[1]

According to VSEPR theory, T-shaped geometry results when three ligands and two lone pairs of electrons are bonded to the central atom, written in AXE notation as AX₃E₂. The T-shaped geometry is related to the trigonal bipyramidal molecular geometry for AX₅ molecules with three equatorial and two axial ligands. In an AX₃E₂ molecule, the two lone pairs occupy two equatorial positions, and the three ligand atoms occupy the two axial positions as well as one equatorial position. The three atoms bond at 90° angles on one side of the central atom, producing the T shape.^[2]

The trifluoroxenate(II) anion, XeF⁻
₃, has been investigated as a possible first example of an AX₃E₃ molecule, which might be expected by VSEPR reasoning to have six electron pairs in an octahedral arrangement with both the three lone pairs and the three ligands in a mer or T-shaped orientations.^[3] Although this anion has been detected in the gas phase, attempts at synthesis in solution and experimental structure determination were unsuccessful. A computational chemistry study showed a distorted planar Y-shaped geometry with the smallest F–Xe–F bond angle equal to 69°, rather than 90° as in a T-shaped geometry.^[3]

References

^ Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann. ISBN 978-0-7506-3365-9.
^ Housecroft, C. E.; Sharpe, A. G. (2004). Inorganic Chemistry (2nd ed.). Prentice Hall. p. 47. ISBN 978-0-13-039913-7.
^ ^a ^b Vasdev, Neil; Moran, Matthew D.; Tuononen, Heikki M.; Chirakal, Raman; Suontamo, Reijo J.; Bain, Alex D.; Schrobilgen, Gary J. (2010). "NMR Spectroscopic Evidence for the Intermediacy of XeF⁻
₃ in XeF₂/F⁻ Exchange, Attempted Syntheses and Thermochemistry of XeF⁻
₃ Salts, and Theoretical Studies of the XeF⁻
₃ Anion". Inorg. Chem. 49 (19): 8997–9004. doi:10.1021/ic101275m. PMID 20799721. S2CID 25413351.

External links

This stereochemistry article is a stub. You can help Wikipedia by expanding it.

[1] Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann. ISBN 978-0-7506-3365-9.

[2] Housecroft, C. E.; Sharpe, A. G. (2004). Inorganic Chemistry (2nd ed.). Prentice Hall. p. 47. ISBN 978-0-13-039913-7.

[Vasdev-3] Vasdev, Neil; Moran, Matthew D.; Tuononen, Heikki M.; Chirakal, Raman; Suontamo, Reijo J.; Bain, Alex D.; Schrobilgen, Gary J. (2010). "NMR Spectroscopic Evidence for the Intermediacy of XeF⁻
₃ in XeF₂/F⁻ Exchange, Attempted Syntheses and Thermochemistry of XeF⁻
₃ Salts, and Theoretical Studies of the XeF⁻
₃ Anion". Inorg. Chem. 49 (19): 8997–9004. doi:10.1021/ic101275m. PMID 20799721. S2CID 25413351.

[1]

[2]

[3]

v t e Molecular geometry
VSEPR theory Coordination number
Coordination number 2	Linear Bent
Coordination number 3	Trigonal planar Trigonal pyramidal T-shaped
Coordination number 4	Tetrahedral Seesaw Square planar
Coordination number 5	Trigonal bipyramidal Square pyramidal Pentagonal planar
Coordination number 6	Octahedral Trigonal prismatic Pentagonal pyramidal
Coordination number 7	Pentagonal bipyramidal Capped octahedral Capped trigonal prismatic
Coordination number 8	Square antiprismatic Dodecahedral Bicapped trigonal prismatic
Coordination number 9	Tricapped trigonal prismatic Capped square antiprismatic
Category

See also

References

External links