Trimethylarsine

Trimethylarsine is the chemical compound with the formula (CH3)3As, commonly abbreviated AsMe3. This organic derivative of arsine (AsH3) has been used as a source of arsenic in microelectronics industry. It is known for it's distinct "garlic" like smell. Trimethylarsine had been discovered as early as 1854.

Structure and Preparation
As predicted by VSEPR theory, AsMe3 is pyramidal with As-C distance of 1.519 Å and C-As-C angles 91.83°

Trimethylarsine can be prepared by treatment of arsenic oxide with trimethylaluminium:
 * As2O3 +  3 AlMe3 →  2 AsMe3  +  Me-(Al-O)n

Properties and reactions
Trimethylarsine is pyrophoric due to the exothermic nature of the following reaction, which initiates combustion:
 * AsMe3 +  1/2 O2  →  OAsMe3 (TMAO)

History
Although poisoning events due to a gas produced by certain micobes was observed and the dependence to the arsenic in paint was assumed. It was not until 1893 that the Italian physician Bartolomeo Gosio published his results on the toxic "Gosio gas" which was subsequently shown to be trimethylarsine. . Under wet conditions mold (scopulariopsis brevicaulis was an very active species) produces significant amounts of arsenic via biomethylation of inorganic pigments especially Paris green or Scheele's Green used in indoor wallpapers which is than released into the air. Newer studies show that trimethylearsine has a low toxicity and could therefor not account for the death and the severe health problems observed in the 19th century.

Safety
Like all organoarsenic compounds, it is considered a carcinogen.