Telluropyrylium
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| Names | |
|---|---|
| Preferred IUPAC name
Telluropyrylium[1] | |
| Other names
Tellurinium; Tellurapyrylium
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
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| Properties | |
| C5H5Te+ | |
| Molar mass | 192.69 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Telluropyrylium is an aromatic heterocyclic compound consisting of a six member ring with five carbon atoms, and a positively charged tellurium atom.[2][3] Derivatives of telluropyrylium are important in research of infrared dyes.[4]
Naming and numbering
[edit]Formerly it was named tellurapyrylium. However this is misleading, as "tellura" indicates that tellurium substitutes for carbon atom, but actually tellurium is substituted for the oxygen atom in pyrilium.[2] In the Hantzsch-Widman system it is called tellurinium. This is the name used by Chemical Abstracts. Replacement nomenclature would call this telluroniabenzene.[2]
Numbering in telluropyrylium starts with 1 on the tellurium atom and counts up to 6 counter-clockwise on the carbon atoms. The positions adjacent to the chalcogen, numbered 2 and 6 can also be called α, the next two positions 3 and 5 can be termed "β" and the opposite carbon at position 4 can be called "γ".
Occurrence
[edit]Because telluropyrylium is a positively charged cation, it takes the solid form as a salt with non-nucleophillic anions like perchlorate, tetrafluoroborate, or hexafluorophosphate.
Properties
[edit]The positive charge is not confined to the tellurium atom in telluropyrylium, but distributes on the ring in several resonance structures, so that the α and γ positions have some positive charge. A nucleophillic attack targets these carbon atoms.
The shape of the telluropyrylium molecule is not a perfect hexagon, as the bond lengths to the tellurium atom at about 2.068 Å compared to about 1.4 Å for the carbon-carbon bonds. The angle at the tellurium atom is also reduced to about 94°, angles at the α and γ carbon atoms in the ring are about 122° and at the β positions 129°. The whole ring is bent so that it forms a boat shape with an angles of 8.7° on the Te-γ axis. (This was measured in the crystal structure of tetraphenyl telluropyrylium-pyrylium monomethine fluoroborate.
Related
[edit]When the ring of telluropyrylium is fused with other aromatic rings larger aromatic structures such as tellurochromenylium, telluroflavylium, and telluroxanthylium result.
See also
[edit]- 6-membered aromatic rings with one carbon replaced by another group: borabenzene, silabenzene, germabenzene, stannabenzene, pyridine, phosphorine, arsabenzene, stibabenzene, bismabenzene, pyrylium, thiopyrylium, selenopyrylium
References
[edit]- ^ International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 1097. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
- ^ a b c Doddi, Giancarlo; Ercolani, Gianfranco (1994). "Thiopyrylium, Selenopyrylium, and Telluropyrylium Salts". Advances in Heterocyclic Chemistry Volume 60. Vol. 60. pp. 65–195. doi:10.1016/S0065-2725(08)60182-8. ISBN 9780120207602.
- ^ Sugimoto, Toyonari (1981). "Reactions of Pyrylium, Thiopyrylium and Selenopyrylium Salts and Their Application to Synthetic Utility". Journal of Synthetic Organic Chemistry, Japan. 39 (1): 1–13. doi:10.5059/yukigoseikyokaishi.39.1.
- ^ Detty, Michael R.; O'regan, Marie B. (1994). "Telluropyrylium Compounds". Chemistry of Heterocyclic Compounds: Tellurium-Containing Heterocycles. Chemistry of Heterocyclic Compounds: A Series of Monographs. Wiley. pp. 219–289. doi:10.1002/9780470187937.ch4. ISBN 9780470187937.
Extra reading
[edit]- Detty, Michael R.; Murray, Bruce J. (December 1982). "Telluropyrylium dyes. 1. 2,6-Diphenyltelluropyrylium dyes". The Journal of Organic Chemistry. 47 (27): 5235–5239. doi:10.1021/jo00148a001.