Arsane
Arsanes (arsine) are chemical compounds made up of the elements arsenic and hydrogen or their derivatives. The arsanes, like the various hydrocarbons, can be classified in a homologous series . The general formula is As n H n + 2 . However, cyclic and polycyclic arsanes As n H n + m (m = 0, −2, −4, −6, ...) are also known, which structurally correspond to the phosphines P n H n + m , but cannot be determined because of their instability (there are, however, isolable organyl and silyl derivatives). There are also organylarsanes R n AsX 3 − n , as well as oligo- and polyarsane organyls As m R n (m> 1) with chains, rings, cages made of single or double linked As atoms.
The term arsine is also used for the most common representative of this group of substances, monoarsane .
The individual representatives of the compounds previously referred to as arsines are now referred to as substituted arsane, for example CH 3 CH 2 AsH 2 as ethyl arsane and C 18 H 15 As as triphenyl arsane .
To avoid ambiguity, the traditional names Arsin etc. should generally be avoided in German.
nomenclature
Based on the nomenclature of the hydrogen compounds of the main group neighbor phosphorus ( phosphanes ), the number of arsenic atoms in the compounds is given with a preceding Greek number. The number of hydrogen atoms is not taken into account in the naming for the sake of simplicity. Example: Diarsan, As 2 H 4 .
The name of a saturated arsenic hydride, in which one or more arsenic atoms have the bond number 5, is formed by providing the locants with a prefix and the λ 5 symbol on the name of the corresponding arsan. In general, the parent hydrides that are richer and poorer in hydrogen and only exist in the form of derivatives, in which the number of H atoms deviates from 3, are identified by a symbol λ n in front of the respective element hydrogen name, separated by a dash .
Example: H 2 AsAsHAsH 2 triarsan, H 4 AsAsH 3 AsH 4 1λ 5 , 2λ 5 , 3λ 5 -triarsan
history
Louis Claude Cadet de Gassicourt heated arsenic in the presence of potassium acetate in 1760 . A mixture of kakodyl (tetramethyldiarsane) and kakodyl oxide (oxybis-dimethylarsane) was formed.
Extraction and presentation
Tertiary arsanes (based on monoarsane, all three hydrogen atoms are exchanged for organic residues: AsH 3 → AsR 3 ) can be obtained from arsenic (III) chloride with the help of organometallic reagents such as Grignard compounds :
properties
Arsanes are very unstable compounds. At the moment only three unsubstituted compounds are known:
- Monoarsan , this is sometimes simply called arsan or, according to the old nomenclature , arsine.
- Diarsan
- Triarsan
They are not resistant to atmospheric oxygen. Sometimes they ignite spontaneously. They react easily with alkyl halides with the addition of a further alkyl radical to form a quaternary arsonium salt , that is to say four organic radicals :
Arsanes are weak Lewis bases . With transition metals they can form a multitude of complexes , with oxygen , sulfur and halogens compounds of the type R 3 AsO, R 3 AsS and R 3 AsCl 2 .
literature
- AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 830.
Individual evidence
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↑ a b c entry on arsanes . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.A00447 Version: 2.3.3. Entry to arsines . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.A00452 Version: 2.3.3.
- ^ A b Arnold F. Holleman, Egon Wiberg: Textbook of inorganic chemistry . de Gruyter, 2007, ISBN 978-3-11-012641-9 , p. 831, 854, 857, 2023 ( limited preview in Google Book search).
- ↑ Wolfgang Liebscher, Ekkehard Fluck: The systematic nomenclature of inorganic chemistry . Springer-Verlag, 2013, ISBN 978-3-642-58368-1 , p. 16 ( limited preview in Google Book search).