Polonium compounds are compounds containing the element polonium. As polonium is radioactive, it has no common compounds, and almost all of its compounds are synthetically created; more than 50 of those are known.[1] The most stable class of polonium compounds are polonides, which are prepared by direct reaction of two elements. Na2Po has the antifluorite structure, the polonides of Ca, Ba, Hg, Pb and lanthanides form a NaCl lattice, BePo and CdPo have the wurtzite and MgPo the nickel arsenide structure. Most polonides decompose upon heating to about 600 °C, except for HgPo that decomposes at ~300 °C and the lanthanide polonides, which do not decompose but melt at temperatures above 1000 °C. For example, the polonide of praseodymium (PrPo) melts at 1250 °C, and that of thulium (TmPo) melts at 2200 °C.[2] PbPo is one of the very few naturally occurring polonium compounds, as polonium alpha decays to form lead.[3]
Hydride
editPolonium hydride (PoH
2) is a volatile liquid at room temperature prone to dissociation; it is thermally unstable.[2] Water is the only other known hydrogen chalcogenide which is a liquid at room temperature; however, this is due to hydrogen bonding. The three oxides, PoO, PoO2 and PoO3, are the products of oxidation of polonium.[4]
Halides
editHalides of the structure PoX2, PoX4 and PoF6 are known. They are soluble in the corresponding hydrogen halides, i.e., PoClX in HCl, PoBrX in HBr and PoI4 in HI.[5] Polonium dihalides are formed by direct reaction of the elements or by reduction of PoCl4 with SO2 and with PoBr4 with H2S at room temperature. Tetrahalides can be obtained by reacting polonium dioxide with HCl, HBr or HI.[6]
Other compounds
editOther polonium compounds include potassium polonite as a polonite, polonate, acetate, bromate, carbonate, citrate, chromate, cyanide, formate, (II) and (IV) hydroxides, nitrate, selenate, selenite, monosulfide, sulfate, disulfate and sulfite.[5][7]
Organopolonium compounds
editA limited organopolonium chemistry is known, mostly restricted to dialkyl and diaryl polonides (R2Po), triarylpolonium halides (Ar3PoX), and diarylpolonium dihalides (Ar2PoX2).[8][9] Polonium also forms soluble compounds with some chelating agents, such as 2,3-butanediol and thiourea.[8]
| Formula | Color | m.p. (°C) | Sublimation temp. (°C) |
Symmetry | Pearson symbol | Space group | No | a (pm) | b(pm) | c(pm) | Z | ρ (g/cm3) | ref |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PoO | black | ||||||||||||
| PoO2 | pale yellow | 500 (dec.) | 885 | fcc | cF12 | Fm3m | 225 | 563.7 | 563.7 | 563.7 | 4 | 8.94 | [11] |
| PoH2 | -35.5 | ||||||||||||
| PoCl2 | dark ruby red | 355 | 130 | orthorhombic | oP3 | Pmmm | 47 | 367 | 435 | 450 | 1 | 6.47 | [12] |
| PoBr2 | purple-brown | 270 (dec.) | [13] | ||||||||||
| PoCl4 | yellow | 300 | 200 | monoclinic | [12] | ||||||||
| PoBr4 | red | 330 (dec.) | fcc | cF100 | Fm3m | 225 | 560 | 560 | 560 | 4 | [13] | ||
| PoI4 | black | [14] |
See also
editReferences
edit- ^ Bagnall, p. 199
- ^ a b Greenwood, p. 766
- ^ Weigel, F. (1959). "Chemie des Poloniums". Angewandte Chemie. 71 (9): 289–316. Bibcode:1959AngCh..71..289W. doi:10.1002/ange.19590710902.
- ^ Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 978-0-12-352651-9.
- ^ a b Figgins, P. E. (1961) The Radiochemistry of Polonium, National Academy of Sciences, US Atomic Energy Commission, pp. 13–14 Google Books
- ^ a b Greenwood, pp. 765, 771, 775
- ^ Bagnall, pp. 212–226
- ^ a b Zingaro, Ralph A. (2011). "Polonium: Organometallic Chemistry". Encyclopedia of Inorganic and Bioinorganic Chemistry. John Wiley & Sons. pp. 1–3. doi:10.1002/9781119951438.eibc0182. ISBN 9781119951438.
- ^ Murin, A. N.; Nefedov, V. D.; Zaitsev, V. M.; Grachev, S. A. (1960). "Production of organopolonium compounds by using chemical alterations taking place during the β-decay of RaE" (PDF). Dokl. Akad. Nauk SSSR (in Russian). 133 (1): 123–125. Retrieved 12 April 2020.
- ^ Wiberg, Egon; Holleman, A. F. and Wiberg, Nils Inorganic Chemistry, Academic Press, 2001, p. 594, ISBN 0-12-352651-5.
- ^ Bagnall, K. W.; d'Eye, R. W. M. (1954). "The Preparation of Polonium Metal and Polonium Dioxide". J. Chem. Soc.: 4295–4299. doi:10.1039/JR9540004295.
- ^ a b Bagnall, K. W.; d'Eye, R. W. M.; Freeman, J. H. (1955). "The polonium halides. Part I. Polonium chlorides". Journal of the Chemical Society (Resumed): 2320. doi:10.1039/JR9550002320.
- ^ a b Bagnall, K. W.; d'Eye, R. W. M.; Freeman, J. H. (1955). "The polonium halides. Part II. Bromides". Journal of the Chemical Society (Resumed): 3959. doi:10.1039/JR9550003959.
- ^ Bagnall, K. W.; d'Eye, R. W. M.; Freeman, J. H. (1956). "657. The polonium halides. Part III. Polonium tetraiodide". Journal of the Chemical Society (Resumed): 3385. doi:10.1039/JR9560003385.