Superatom

In chemistry, a superatom is any cluster of atoms that seem to exhibit some of the properties of elemental atoms.[1]

Sodium atoms, when cooled from vapor, naturally condense into clusters, preferentially containing a magic number of atoms (2, 8, 20, 40, 58, etc.), with the outermost electron of each atom entering an orbital encompassing all the atoms in the cluster. Superatoms tend to behave chemically in a way that will allow them to have a closed shell of electrons, in this new counting scheme.[citation needed]

Aluminum clusters

Certain aluminum clusters have superatom properties. These aluminium clusters are generated as anions (Al−
n with n = 1, 2, 3, … ) in helium gas and reacted with a gas containing iodine. When analyzed by mass spectrometry one main reaction product turns out to be Al
13I−
.[2] These clusters of 13 aluminium atoms with an extra electron added do not appear to react with oxygen when it is introduced in the same gas stream, indicating a halide-like character and a magic number of 40 free electrons. Such a cluster is known as a superhalogen.[3][4][5][6] The cluster component in Al
13I−
 ion is similar to an iodide ion or better still a bromide ion. The related Al
13I−
2 cluster is expected to behave chemically like the triiodide ion.[2]

Similarly it has been noted that Al
14 clusters with 42 electrons (2 more than the magic numbers) appear to exhibit the properties of an alkaline earth metal which typically adopt +2 valence states. This is only known to occur when there are at least 3 iodine atoms attached to an Al−
14 cluster, Al
14I−
3. The anionic cluster has a total of 43 itinerant electrons, but the three iodine atoms each remove one of the itinerant electrons to leave 40 electrons in the jellium shell.[7][8]

It is particularly easy and reliable to study atomic clusters of inert gas atoms by computer simulation because interaction between two atoms can be approximated very well by the Lennard-Jones potential. Other methods are readily available and it has been established that the magic numbers are 13, 19, 23, 26, 29, 32, 34, 43, 46, 49, 55, etc.[9]

Other clusters

  • Li(HF)3Li = the (HF)3 interior causes 2 valence electrons from the Li to orbit the entire molecule as if it were an atom's nucleus.[12]
  • Li(NH3)4 = Has one diffuse electron orbiting around Li(NH3)+4 core, i.e., mimics an alkali-metal atom.[13][14]
  • Be(NH3)4 = Has two diffuse electrons orbiting around Be(NH3)2+4 core, i.e., mimics He-atom.[15][14]

Superatom complexes

Superatom complexes are a special group of superatoms that incorporate a metal core which is stabilized by organic ligands. In thiolate-protected gold cluster complexes a simple electron counting rule can be used to determine the total number of electrons (ne) which correspond to a magic number via,

where N is the number of metal atoms (A) in the core, v is the atomic valence, M is the number of electron withdrawing ligands, and z is the overall charge on the complex.[19] For example the Au102(p-MBA)44 has 58 electrons and corresponds to a closed shell magic number.[20]

Gold superatom complexes

  • Au25(SMe)−18[21]
  • Au102(p−MBA)44
  • Au144(SR)60[22]

Other superatom complexes

  • Ga23(N(Si(CH3)3)2)11[23]
  • Al50(C5(CH3)5)12[24]
  • Re6Se8Cl2 – In 2018 researchers produced 15-nm-thick flakes of this superatomic material. They anticipate that a monolayer will be a superatomic 2-D semiconductor and offer new 2-D materials with unusual, tunable properties.[25]
  • Organo− Zintl-based superatoms:[Ge9(CHO)3] and [Ge9(CHO)][26]

See also

References

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  2. ^ a b Bergeron, D. E. (2 April 2004). "Formation of Al
    13    I−
    : Evidence for the Superhalogen Character of Al13". Science. 304 (5667). American Association for the Advancement of Science (AAAS): 84–87. doi:10.1126/science.1093902. ISSN 0036-8075. PMID 15066775. S2CID 26728239.
  3. ^ Reddy, G. Naaresh; Parida, Rakesh; Giri, Santanab (2017-12-12). "Functionalized deltahedral Zintl complexes Ge9R3 (R = CF3, CN, and NO2): a new class of superhalogens". Chemical Communications. 53 (99): 13229–13232. doi:10.1039/C7CC08120K. ISSN 1364-548X. PMID 29182179.
  4. ^ Giri, Santanab; Child, Brandon Z.; Jena, Puru (2014). "Organic Superhalogens". ChemPhysChem. 15 (14): 2903–2908. doi:10.1002/cphc.201402472. ISSN 1439-7641. PMID 25056518.
  5. ^ Reddy, Gorre Naaresh; Giri, Santanab (2016-05-10). "Super/hyperhalogen aromatic heterocyclic compounds". RSC Advances. 6 (52): 47145–47150. Bibcode:2016RSCAd...647145R. doi:10.1039/C6RA08625J. ISSN 2046-2069.
  6. ^ Sinha, Swapan; Jena, Puru; Giri, Santanab (2022-08-12). "Functionalized nona-silicide [Si9R3] Zintl clusters: a new class of superhalogens". Physical Chemistry Chemical Physics. 24 (35): 21105–21111. Bibcode:2022PCCP...2421105S. doi:10.1039/D2CP02619H. ISSN 1463-9084. OSTI 1978872. PMID 36018293. S2CID 251551751.
  7. ^ Philip Ball, "A New Kind of Alchemy", New Scientist Issue dated 2005-04-16.
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  9. ^ Harris, I. A.; Kidwell, R. S.; Northby, J. A. (17 December 1984). "Structure of Charged Argon Clusters Formed in a Free Jet Expansion". Physical Review Letters. 53 (25). American Physical Society (APS): 2390–2393. Bibcode:1984PhRvL..53.2390H. doi:10.1103/physrevlett.53.2390. ISSN 0031-9007. S2CID 13793440.
  10. ^ a b Naiche Owen Jones, 2006.[permanent dead link]
  11. ^ Das, Ujjal; Raghavachari, Krishnan (2008). "Al5O4 Superatom with Potential for New Materials Design". Journal of Chemical Theory and Computation. 4 (12): 2011–2019. doi:10.1021/ct800232b. PMID 26620474.
  12. ^ Sun, Xiao-Ying; Li, Zhi-Ru; Wu, Di; Sun, Chia-Chung (2007). "Extraordinary superatom containing double shell nucleus: Li(HF)3Li connected mainly by intermolecular interactions". International Journal of Quantum Chemistry. 107 (5). Wiley: 1215–1222. Bibcode:2007IJQC..107.1215S. doi:10.1002/qua.21246. ISSN 0020-7608.
  13. ^ Ariyarathna, Isuru R.; Pawłowski, Filip; Ortiz, Joseph Vincent; Miliordos, Evangelos (2018). "Molecules mimicking atoms: monomers and dimers of alkali metal solvated electron precursors". Physical Chemistry Chemical Physics. 20 (37): 24186–24191. Bibcode:2018PCCP...2024186A. doi:10.1039/C8CP05497E. ISSN 1463-9076. PMID 30209476.
  14. ^ a b Ariyarathna, Isuru (2021-03-01). First Principle Studies on Ground and Excited Electronic States: Chemical Bonding in Main-Group Molecules, Molecular Systems with Diffuse Electrons, and Water Activation using Transition Metal Monoxides (PhD thesis).
  15. ^ Ariyarathna, Isuru R.; Khan, Shahriar N.; Pawłowski, Filip; Ortiz, Joseph Vincent; Miliordos, Evangelos (2018-01-04). "Aufbau Rules for Solvated Electron Precursors: Be(NH 3 ) 4 2+ Complexes and Beyond". The Journal of Physical Chemistry Letters. 9 (1): 84–88. doi:10.1021/acs.jpclett.7b03000. ISSN 1948-7185. PMID 29232138.
  16. ^ Koyasu, Kiichirou; Atobe, Junko; Akutsu, Minoru; Mitsui, Masaaki; Nakajima, Atsushi (2007). "Electronic and Geometric Stabilities of Clusters with Transition Metal Encapsulated by Silicon". The Journal of Physical Chemistry A. 111 (1). American Chemical Society (ACS): 42–49. Bibcode:2007JPCA..111...42K. doi:10.1021/jp066757f. ISSN 1089-5639. PMID 17201386.
  17. ^ Platinum nanoclusters go magnetic Archived 2007-10-15 at the Wayback Machine, nanotechweb.org, 2007
  18. ^ Ultra Cold Trap Yields Superatom, NIST, 1995
  19. ^ Walter, M.; Akola, J.; Lopez-Acevedo, O.; Jadzinsky, P. D.; Calero, G.; Ackerson, C. J.; Whetten, R. L.; Gronbeck, H.; Hakkinen, H. (1 June 2008). "A unified view of ligand-protected gold clusters as superatom complexes". Proceedings of the National Academy of Sciences. 105 (27): 9157–9162. Bibcode:2008PNAS..105.9157W. doi:10.1073/pnas.0801001105. ISSN 0027-8424. PMC 2442568. PMID 18599443.
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  21. ^ Akola, Jaakko; Walter, Michael; Whetten, Robert L.; Häkkinen, Hannu; Grönbeck, Henrik (2008). "On the Structure of Thiolate-Protected Au25". Journal of the American Chemical Society. 130 (12). American Chemical Society (ACS): 3756–3757. doi:10.1021/ja800594p. ISSN 0002-7863. PMID 18321117.
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  23. ^ Hartig, Jens; Stößer, Anna; Hauser, Petra; Schnöckel, Hansgeorg (26 February 2007). "A Metalloid Ga23{N(SiMe3)2}11 Cluster: The Jellium Model Put to Test". Angewandte Chemie International Edition. 46 (10). Wiley: 1658–1662. doi:10.1002/anie.200604311. ISSN 1433-7851. PMID 17230594.
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  25. ^ Zyga, Lisa. "Researchers create first superatomic 2-D semiconductor". Phys.org. Retrieved 2018-02-18.
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