A sextuple bond is a type of covalent bond involving 12 bonding electrons and in which the bond order is 6. The only known molecules with true sextuple bonds are the diatomic dimolybdenum (Mo₂) and ditungsten (W₂), which exist in the gaseous phase at very low temperatures. There is strong evidence to believe that no two elements in the periodic table can form a bond with greater order than 6.^[1]

Contents 1 Dimolybdenum and ditungsten 2 Other molecules 3 References 4 See also

[edit] Dimolybdenum and ditungsten

Dimolybdenum (Mo₂) can be observed in the gas phase at low temperatures (7K) by a laser evaporation technique using molybdenum sheet with, for instance, near infrared spectroscopy or UV spectroscopy.^[2] Like dichromium, a singlet state is expected from dimolybdenum.^[3] Higher bond order is reflected in shorter bond length of 194 pm.

[edit] Other molecules

Although diatomic Cr₂ and U₂ have formal structures with twelve-electron bonds, their effective bond orders derived from quantum chemistry calculations are less than 5 (which would be quintuple bonds).^[1]

[edit] References

[edit] See also

• Norman, Joe G., Jr.; Ryan, P. Barry (1980). "Metal-metal bond energies in diatomic molybdenum, octachloromolybdate (Mo2Cl84-), and molybdenum formate (Mo2(O2CH)4)". Journal of Computational Chemistry 1 (1): 59–63. doi:10.1002/jcc.540010107. 
• Atha, P. M.; Hillier, I. H.; Guest, M. F. (1980). "Electron correlation and the nature of the sextuple bond in the dimolybdenum molecule". Chemical Physics Letters 75 (1): 84–86. doi:10.1016/0009-2614(80)80469-6. 
• Wood, Carol; Doran, Mark; Hillier, Ian H.; Guest, Martyn F. (1980). "Theoretical study of the electronic structure of the transition metal dimers, discandium, dichromium, dimolybdenum, and dinickel". Faraday Symp. R. Soc. Chem. 14 (Diatomic Met. Met. Clusters): 159–169. doi:10.1039/fs9801400159. 

v • d • e Chemical bonds Intramolecular ("strong") Covalent bonds Sigma bond · Pi bond · Delta bond Double bond · Triple bond · Quadruple bond · Quintuple bond · Sextuple bond 3c-2e · 3c-4e · 4c-2e Agostic bond · Bent bond · Dipolar bond · Pi backbond Conjugation · Hyperconjugation · Aromaticity · Hapticity · Antibonding Ionic bonds cation-pi bond · salt bond Metallic bonds Metal aromaticity Intermolecular ("weak") Hydrogen bond Dihydrogen bond · Dihydrogen complex · Low-barrier hydrogen bond · Symmetric hydrogen bond Other noncovalent van der Waals force · London dispersion force · Mechanical bond · Halogen bond · Aurophilicity · Intercalation · Stacking · Entropic force · Chemical polarity Note: the weakest strong bonds are not necessarily stronger than the strongest weak bonds