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Structure of the Bi2+
8
cluster in [Bi8](GaCl4)2. The Bi–Bi bond lengths are 3.07 Å.[1]

Bismuth polycations are polyatomic ions of the formula Bin+
x
. They were originally observed in solutions of bismuth metal in molten bismuth chloride.[2] It has since been found that these clusters are present in the solid state, particularly in salts where germanium tetrachloride or tetrachloroaluminate serve as the counteranions, but also in amorphous phases such as glasses and gels.[3][4][5][6][7] Bismuth endows materials with a variety of interesting optical properties that can be tuned by changing the supporting material.[8][9][10][11] Commonly-reported structures include the trigonal bipyramidal Bi3+
5
cluster, the octahedral Bi2+
6
cluster, the square antiprismatic Bi2+
8
cluster, and the tricapped trigonal prismatic Bi5+
9
cluster.

Known materials

Crystalline

Metal complexes

  • [CuBi8][AlCl4]3[12]
  • [Ru(Bi8)2]6+[13]
  • [Ru2Bi14Br4][AlCl4]4[13]

Structure and bonding

Bismuth polycations form despite the fact that they possess fewer total valence electrons than would seem necessary for the number of sigma bonds. The shapes of these clusters are generally dictated by Wade's rules, which are based on the treatment of the electronic structure as delocalized molecular orbitals. The bonding can also be described with three-center two-electron bonds in some cases, such as the Bi3+
5
cluster. Bismuth clusters have been observed to act as ligands for copper[14] and ruthenium[15] ions. This behavior is possible due to the otherwise fairly inert lone pairs on each of the bismuth that arise primarily from the s-orbitals left out of Bi–Bi bonding.

The 0.60 isosurface of the ELF of a Bi2+
8
cluster. Localizations around the nuclei are pink and lone pairs are purple.

Optical properties

The variety of electron-deficient sigma aromatic clusters formed by bismuth gives rise to a wide range of spectroscopic behaviors. Of particular interest are the systems capable of low-energy electronic transitions, as these have demonstrated potential as near-infrared light emitters. It is the tendency of electron-deficient bismuth to form sigma-delocalized clusters with small HOMO/LUMO gaps that gives rise to the near-infrared emissions. This property makes these species potentially valuable to the field of near-infrared optical tomography, which exploits the near-infrared window in biological tissue.[11]

References

  1. ^ a b c Lindsjö, Andreas Fischer, Martin; Kloo, Lars (2005-02-01). "Improvements of and Insights into the Isolation of Bismuth Polycations from Benzene Solution – Single-Crystal Structure Determinations of Bi8[GaCl4]2 and Bi5[GaCl4]3". European Journal of Inorganic Chemistry. 2005 (4): 670–675. doi:10.1002/ejic.200400466. ISSN 1099-0682.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ^ Day, Graeme; Glaser, Rainer; Shimomura, Noriyuki; Takamuku, Atsushi; Ichikawa, Kazuhiko (2000-03-17). "Electronic Excitations in Homopolyatomic Bismuth Cations: Spectroscopic Measurements in Molten Salts and an ab initio CI-Singles Study". Chemistry – A European Journal. 6 (6): 1078–1086. doi:10.1002/(sici)1521-3765(20000317)6:6<1078::aid-chem1078>3.0.co;2-r. ISSN 1521-3765. PMID 10785828.
  3. ^ Fujimoto, Yasushi; Nakatsuka, Masahiro (March 2001). "Infrared Luminescence from Bismuth-Doped Silica Glass". Japanese Journal of Applied Physics. 40 (Part 2, No. 3B): L279–L281. Bibcode:2001JaJAP..40L.279F. doi:10.1143/jjap.40.l279. ISSN 1347-4065. S2CID 250811099.
  4. ^ Dianov, Evgenii M.; Dvoyrin, V. V.; Mashinsky, V. M.; Umnikov, A. A.; Yashkov, M. V.; Gur'yanov, A. N. (2005). "CW bismuth fibre laser". Quantum Electronics. 35 (12): 1083–1084. Bibcode:2005QuEle..35.1083D. doi:10.1070/qe2005v035n12abeh013092. S2CID 250774487.
  5. ^ Zhou, Shifeng; Jiang, Nan; Zhu, Bin; Yang, Hucheng; Ye, Song; Lakshminarayana, Gandham; Hao, Jianhua; Qiu, Jianrong (2008-05-09). "Multifunctional Bismuth-Doped Nanoporous Silica Glass: From Blue-Green, Orange, Red, and White Light Sources to Ultra-Broadband Infrared Amplifiers". Advanced Functional Materials. 18 (9): 1407–1413. doi:10.1002/adfm.200701290. hdl:10397/21390. ISSN 1616-3028. S2CID 136501137.
  6. ^ Razdobreev, Igor; El Hamzaoui, Hicham; Bouwmans, Géraud; Bouazaoui, Mohamed; Arion, Vladimir B. (2012-02-01). "Photoluminescence of sol-gel silica fiber preform doped with Bismuth-containing heterotrinuclear complex". Optical Materials Express. 2 (2): 205–213. Bibcode:2012OMExp...2..205R. doi:10.1364/ome.2.000205. ISSN 2159-3930.
  7. ^ Sun, Hong-Tao; Yang, Junjie; Fujii, Minoru; Sakka, Yoshio; Zhu, Yufang; Asahara, Takayuki; Shirahata, Naoto; Ii, Masaaki; Bai, Zhenhua (2011-01-17). "Highly Fluorescent Silica-Coated Bismuth-Doped Aluminosilicate Nanoparticles for Near-Infrared Bioimaging". Small. 7 (2): 199–203. doi:10.1002/smll.201001011. ISSN 1613-6829. PMID 21213381.
  8. ^ Cao, Renping; Peng, Mingying; Zheng, Jiayu; Qiu, Jianrong; Zhang, Qinyuan (2012-07-30). "Superbroad near to mid infrared luminescence from closo-deltahedral Bi3+
    5
    cluster in Bi5(GaCl4)3"
    . Optics Express. 20 (16): 18505–18514. Bibcode:2012OExpr..2018505C. doi:10.1364/oe.20.018505. ISSN 1094-4087. PMID 23038400.
  9. ^ Sun, Hong-Tao; Xu, Beibei; Yonezawa, Tetsu; Sakka, Yoshio; Shirahata, Naoto; Fujii, Minoru; Qiu, Jianrong; Gao, Hong (2012-08-28). "Photoluminescence from Bi5(GaCl4)3 molecular crystal". Dalton Transactions. 41 (36): 11055–61. arXiv:1205.6889. doi:10.1039/c2dt31167d. ISSN 1477-9234. PMID 22864825. S2CID 19202220.
  10. ^ a b c Sun, Hong-Tao; Sakka, Yoshio; Shirahata, Naoto; Gao, Hong; Yonezawa, Tetsu (2012-06-06). "Experimental and theoretical studies of photoluminescence from Bi2+
    8
    and Bi3+
    5
    stabilized by [AlCl4] in molecular crystals". Journal of Materials Chemistry. 22 (25): 12837. arXiv:1202.5395. doi:10.1039/c2jm30251a. ISSN 1364-5501. S2CID 95074461.
  11. ^ a b Sun, Hong-Tao; Zhou, Jiajia; Qiu, Jianrong (2014). "Recent advances in bismuth activated photonic materials". Progress in Materials Science. 64: 1–72. doi:10.1016/j.pmatsci.2014.02.002.
  12. ^ Kou, C. Y.; Zhuang, L.; Wang, G. Q.; Cui, H.; Yuan, H. K.; Tian, C. L.; Wang, J. Z.; Chen, H. (2015-10-27). "[TM13@Bi20] clusters in three-shell icosahedral matryoshka structure: being as superatoms". RSC Advances. 5 (112): 92134–92143. doi:10.1039/c5ra19194g. ISSN 2046-2069.
  13. ^ a b Groh, Matthias F.; Isaeva, Anna; Frey, Christoph; Ruck, Michael (2013-11-01). "[Ru(Bi8)2]6+ – A Cluster in a Highly Disordered Crystal Structure is the Key to the Understanding of the Coordination Chemistry of Bismuth Polycations". Zeitschrift für Anorganische und Allgemeine Chemie. 639 (14): 2401–2405. doi:10.1002/zaac.201300377. ISSN 1521-3749.
  14. ^ Knies, Maximilian; Kaiser, Martin; Isaeva, Anna; Müller, Ulrike; Doert, Thomas; Ruck, Michael (2018). "The Intermetalloid Cluster Cation (CuBi8)3+". Chemistry – A European Journal. 24 (1): 127–132. doi:10.1002/chem.201703916. ISSN 1521-3765. PMID 28977714.
  15. ^ Groh, Matthias F.; Isaeva, Anna; Frey, Christoph; Ruck, Michael (2013-11-01). "[Ru(Bi8)2]6+ – A Cluster in a Highly Disordered Crystal Structure is the Key to the Understanding of the Coordination Chemistry of Bismuth Polycations". Zeitschrift für Anorganische und Allgemeine Chemie. 639 (14): 2401–2405. doi:10.1002/zaac.201300377. ISSN 1521-3749.