Organoarsines

Organoarsines are organic compounds in which carbon is directly bonded to arsenic. The most common classes are trialkylarsines (R3As) and triarylarsines (Ar3As), in which arsenic is typically in the +3 oxidation state and bears a lone pair, giving a pyramidal geometry at arsenic. Diaryl- and mono-substituted arsones (R2AsR') also occur. The C–As bond is generally quite robust, and these compounds can be prepared with a variety of alkyl or aryl substituents.

Synthesis of organoarsines typically involves substitution of chlorine ligands on arsenic precursors with organometallic reagents. Common routes use arsenic trichloride (AsCl3) or diarylarsenyl chlorides (ArAsCl2) reacting with organolithium or Grignard reagents, followed by workup to yield the target R3As. Other approaches include coupling reactions that incorporate carbon substituents onto preformed arsenic centers. The resulting organoarsines are usually neutral molecules, though some derivatives can form cations or participate in broader arsenic-containing frameworks.

In coordination chemistry, organoarsines are used as ligands for transition metals. They resemble phosphines as σ-donor ligands and can stabilize various metal oxidation states; triphenylarsine and related derivatives have been utilized in catalytic applications, including hydrofunctionalization and cross-coupling, though they are less common than their phosphorus analogs due to toxicity and limited availability.

Safety considerations are important: organoarsines are generally toxic, and many arsenic compounds pose significant health risks. Handling requires appropriate controls and disposal in accordance with regulatory guidelines.