Triple bond

Atriple bondinchemistryis achemical bondbetween twoatomsinvolving sixbonding electronsinstead of the usual two in acovalent single bond.Triple bonds are stronger than the equivalentsingle bondsordouble bonds,with abond orderof three. The most common triple bond is in anitrogenN₂molecule; the second most common is that between twocarbonatoms, which can be found inalkynes.Otherfunctional groupscontaining a triple bond arecyanidesandisocyanides.Some diatomic molecules, such asdiphosphorus^[1]andcarbon monoxide,are also triple bonded. Inskeletal formulaethe triple bond is drawn as three parallel lines (≡) between the two connected atoms.^[2]^[3]^[4]

Chemical compounds with triple bond(s)

acetylene,H−C≡C−H	cyanogen,N≡C−C≡N	carbon monoxide,C≡O

Bonding

Triple bonding can be explained in terms oforbital hybridization.In the case of acetylene, each carbon atom has twosp-orbitalsand twop-orbitals.The two sp-orbitals are linear, with 180°bond angles,and occupy the x-axis in thecartesian coordinate system.The p-orbitals areperpendicularto the sp-orbitals on the y-axis and the z-axis. When the atoms approach each other, the sp orbitals overlap to form an sp-spsigma bond.At the same time the p_z-orbitals approach and together they form a p_z-p_zpi-bond.Likewise, the other pair of p_y-orbitals form a p_y-p_ypi-bond. The result is formation of one sigma bond and two pi bonds.

In thebent bond model,the triple bond can also formed by the overlapping of three sp³lobes without the need to invoke a pi-bond.^[5]

Triple bonds between elements heavier than oxygen

Structure ofhexa(tert-butoxy)ditungsten(III),an example of a metal-metal triple bond.

Many elements beyond oxygen can form triple bonds. These bonds are common in some transition metals.Hexa(tert-butoxy)ditungsten(III)andHexa(tert-butoxy)dimolybdenum(III)are well known examples, in which the metal-metal bond distance is about 233 pm.^[6]Hexa(tert-butoxy)ditungsten(III)has attracted particular attention for its reactions with alkynes, leading to metal-carbon triple bonded compounds of the formula RC≡W(OBut)₃^[7]

Additionally,phosphoruscan exist as the highly reactive diatomic moleculediphosphorus,which has roughly half thebond-dissociation energyof dinitrogen.^[1]

References

^^a ^bHuber, K. P.; Herzberg, G. (1979).Molecular Spectra and Molecular Structure IV. Constants of Diatomic Molecules.New York: Van Nostrand.ISBN 978-0442233945.
^March, Jerry(1985),Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 3rd edition,New York: Wiley,ISBN 9780471854722,OCLC 642506595
^Organic Chemistry2nd Ed. John McMurry
^Pyykkö, Pekka; Riedel, Sebastian; Patzschke, Michael (2005). "Triple-Bond Covalent Radii".Chemistry: A European Journal.11(12): 3511–20.doi:10.1002/chem.200401299.PMID 15832398.
^Advanced Organic ChemistryCarey, Francis A., Sundberg, Richard J. 5th ed. 2007
^Chisholm, Malcolm H.; Gallucci, Judith C.; Hollandsworth, Carl B. (2006). "Crystal and molecular structure of W₂(OBut)₆and electronic structure calculations on various conformers of W₂(OMe)₆".Polyhedron.25(4): 827–833.doi:10.1016/j.poly.2005.07.010.
^.Listemann, Mark L.; Schrock, Richard R. (1985). "Multiple metal carbon Bonds. 35. A General Route to tri-tert-Butoxytungsten Alkylidyne complexes. Scission of Acetylenes by Ditungsten Hexa-tert-butoxide ".Organometallics.4:74–83.doi:10.1021/om00120a014.

[Herzberg-1] Huber, K. P.; Herzberg, G. (1979).Molecular Spectra and Molecular Structure IV. Constants of Diatomic Molecules.New York: Van Nostrand.ISBN 978-0442233945.

[2] March, Jerry(1985),Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 3rd edition,New York: Wiley,ISBN 9780471854722,OCLC 642506595

[3] Organic Chemistry2nd Ed. John McMurry

[4] Pyykkö, Pekka; Riedel, Sebastian; Patzschke, Michael (2005). "Triple-Bond Covalent Radii".Chemistry: A European Journal.11(12): 3511–20.doi:10.1002/chem.200401299.PMID 15832398.

[5] Advanced Organic ChemistryCarey, Francis A., Sundberg, Richard J. 5th ed. 2007

[6] Chisholm, Malcolm H.; Gallucci, Judith C.; Hollandsworth, Carl B. (2006). "Crystal and molecular structure of W₂(OBut)₆and electronic structure calculations on various conformers of W₂(OMe)₆".Polyhedron.25(4): 827–833.doi:10.1016/j.poly.2005.07.010.

[7] .Listemann, Mark L.; Schrock, Richard R. (1985). "Multiple metal carbon Bonds. 35. A General Route to tri-tert-Butoxytungsten Alkylidyne complexes. Scission of Acetylenes by Ditungsten Hexa-tert-butoxide ".Organometallics.4:74–83.doi:10.1021/om00120a014.

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