In chemistry, an arsaalkyne is chemical compound with a

triple bond A triple bond in chemistry is a chemical bond between two atoms involving six bonding electrons instead of the usual two in a covalent single bond. Triple bonds are stronger than the equivalent single bonds or double bonds, with a bond order o ...

between carbon and

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, ...

. These

organoarsenic compound Organoarsenic chemistry is the chemistry of compounds containing a chemical bond between arsenic and carbon. A few organoarsenic compounds, also called "organoarsenicals," are produced industrially with uses as insecticides, herbicides, and fu ...

s are rare, especially in comparison with the

phosphaalkyne In chemistry, a phosphaalkyne (IUPAC name: alkylidynephosphane) is an organophosphorus compound containing a triple bond between phosphorus and carbon with the general formula R-C≡P. Phosphaalkynes are the heavier congeners of nitriles, though, ...

s. The parent HCAs has been characterized spectroscopically, otherwise the only arsaalkynes have bulky organic substituents.

Synthesis and isolation

Arsaalkynes are produced by

dehydrohalogenation In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications. Dehydrohalogenation from alkyl halid ...

or related base-induced

elimination reaction An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one- or two-step mechanism. The one-step mechanism is known as the E2 reaction, and the two-step mechanism is known as the E1 r ...

s. The case of HCAs is illustrative: : Owing to the principles of the

double bond rule In chemistry, the double bond rule states that elements with a principal quantum number greater than 2 for their valence electrons ( period 3 elements and higher) tend not to form multiple bonds (e.g. double bonds and triple bonds). The double b ...

, arsaalkynes tend to oligomerize more readily than the phosphorus analogues. Thus attempts to prepare AsCCMe₃ produce the

tetramer A tetramer () ('' tetra-'', "four" + '' -mer'', "parts") is an oligomer formed from four monomers or subunits. The associated property is called ''tetramery''. An example from inorganic chemistry is titanium methoxide with the empirical formula ...

, which has a

cubane Cubane () is a synthetic hydrocarbon compound that consists of eight carbon atoms arranged at the corners of a cube, with one hydrogen atom attached to each carbon atom. A solid crystalline substance, cubane is one of the Platonic hydrocarbons an ...

structure. The very bulky substituent C₆H₂-2,4,6-(''t''-Bu)₃ does however allow the crystallization of the monomeric arsaalkyne. Its As-C bond length is 1.657(7) Å.{{cite journal , doi=10.1039/C39940002061, title=Synthesis, Crystal and Molecular Structure of the First Metal Complex [Pt(PPh₃)₂{η²-As≡C(C6H2Bu^t₃)}] Derived from an Arsaalkyne , year=1994 , last1=Hitchcock , first1=Peter B. , last2=Jones , first2=Cameron , last3=Nixon , first3=John F. , journal=J. Chem. Soc., Chem. Commun. , issue=18 , pages=2061–2062

References

Functional groups Organoarsenic compounds

Synthesis and isolation

See also

References