HOMO and LUMO
Inchemistry,HOMOandLUMOare types ofmolecular orbitals.The acronyms stand forhighest occupied molecular orbitalandlowest unoccupied molecular orbital,respectively. HOMO and LUMO are sometimes collectively called thefrontier orbitals,such as in thefrontier molecular orbital theory.
Gap
[edit]The energy difference between the HOMO and LUMO isthe HOMO–LUMO gap.Its size can be used to predict the strength and stability oftransition metalcomplexes,as well as the colors they produce in solution.[1]As a rule of thumb, the smaller a compound's HOMO–LUMO gap, the less stable the compound.[2]
Semiconductors
[edit]The HOMO level is toorganic semiconductorsroughly what the maximumvalence bandis to inorganicsemiconductorsandquantum dots.The same analogy can be made between the LUMO level and theconduction bandminimum.[3]
Organometallic chemistry
[edit]In organometallic chemistry, the size of the LUMO lobe can help predict whereaddition to pi ligandswill occur.
SOMO
[edit]ASOMOis asingly occupied molecular orbitalsuch as half-filled HOMO of aradical.[4]This abbreviation may also be extended tosemi occupied molecular orbital.
Subadjacent orbitals: NHOMO and SLUMO
[edit]If existent, the molecular orbitals at one energy level below the HOMO and one energy level above the LUMO are also found to play a role in frontier molecular orbital theory. They are namedNHOMOfornext-to-highest occupied molecular orbitalandSLUMOforsecond lowest unoccupied molecular orbital.[5]These are also commonly referred to as HOMO−1 and LUMO+1 respectively.[6]
See also
[edit]- Diels–Alder reaction
- Electron configuration
- Klopman–Salem equation
- Koopmans' theorem
- Ligand
- Woodward–Hoffmann rules
References
[edit]- ^Griffith, J. S. and L. E. Orgel."Ligand Field Theory".Q. Rev. Chem. Soc.1957, 11, 381–383.
- ^Malik, Bashir Ahmad; Mir, Jan Mohammad (2018-01-02)."Synthesis, characterization and DFT aspects of some oxovanadium(IV) and manganese(II) complexes involving dehydroacetic acid and β-diketones".Journal of Coordination Chemistry.71(1): 104–119.doi:10.1080/00958972.2018.1429600.ISSN0095-8972.
- ^Bredas, J,-L."Mind the gap!".Mater. Horiz.2014, 1, 17–19.
- ^IUPAC,Compendium of Chemical Terminology,2nd ed. (the "Gold Book" ) (1997). Online corrected version: (2006–) "SOMO".doi:10.1351/goldbook.S05765.
- ^IUPAC,Compendium of Chemical Terminology,2nd ed. (the "Gold Book" ) (1997). Online corrected version: (2006–) "subjacent orbital".doi:10.1351/goldbook.S06067.
- ^"HOMO (Molecular Orbital) – an overview".ScienceDirect Topics.
Further reading
[edit]- Fleming, Ian (21 December 2009).Molecular Orbitals and Organic Chemical Reactions.pp. 1–360.ISBN9780470746592.
External links
[edit]- OrbiMolMolecular orbital database
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