1,2-Bis(dimethylarsino)benzene (diars) is the

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 ...

with the formula CH(As(CH)). The molecule consists of two di methylarsino groups attached to adjacent carbon centers of a

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...

ring. It is a

chelating Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are ...

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...

in coordination chemistry. This colourless oil is commonly abbreviated "diars."

Coordination chemistry

Related, but non-chelating organoarsenic ligands include

triphenylarsine Triphenylarsine is the chemical compound with the formula As(C6H5)3. This organoarsenic compound, often abbreviated As Ph3, is a colorless crystalline solid that is used as a ligand and a reagent in coordination chemistry and organic synthesis. T ...

and

trimethylarsine Trimethylarsine (abbreviated TMA or TMAs) is the chemical compound with the formula (CH3)3As, commonly abbreviated As Me3 or TMAs. This organic derivative of arsine has been used as a source of arsenic in microelectronics industry, a building bloc ...

. Work on diars preceded the development of the chelating diphosphine ligands such as

dppe 1,2-Bis(diphenylphosphino)ethane (dppe) is an organophosphorus compound with the formula (PhPCH) (Ph = phenyl). It is a commonly used bidentate ligand in coordination chemistry. It is a white solid that is soluble in organic solvents. Preparation ...

, which are now prevalent in

homogeneous catalysis In chemistry, homogeneous catalysis is catalysis by a soluble catalyst in a solution. Homogeneous catalysis refers to reactions where the catalyst is in the same phase as the reactants, principally in solution. In contrast, heterogeneous catalysi ...

. Diars is a bidentate ligand used in coordination chemistry. It was first described in 1939, but was popularized by R. S. Nyholm for its ability to stabilize metal complexes with unusual oxidation states and coordination numbers, e.g. TiCl(diars). High coordination numbers arise because diars is fairly compact and the As-M bonds are long, which relieves crowding at the metal center. In terms of stabilizing unusual oxidation states, diars stabilizes Ni(III), as in iCl(diars)l. Of historical interest is the supposedly diamagnetic i(diars)ClO), obtained by heating nickel perchlorate with diars. Octahedral ''d'' complexes characteristically have triplet ground states, so the diamagnetism of this complex was puzzling. Later by

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

, the complex was shown to be pentacoordinate with the formula i(triars)(diars)ClO), where triars is the tridentate ligand HAs(CH)s(CH), arising from the elimination of

Preparation and handling

Diars is prepared by the reaction of ''ortho''-dichlorobenzene and sodium dimethylarsenide:Feltham, R. D.; Silverthorn, W. "''o''-Phenylenebis(dimethylarsine)" Inorganic Syntheses 1967, Vol. X, pp. 159–164. :CHCl + 2 NaAs(CH) → CH(As(CH)) + 2 NaCl It is a colorless liquid. Oxygen converts diars to the dioxide, CH(As(CH)O).

References

{{DEFAULTSORT:Bis(dimethylarsino)benzene, 1, 2- Benzene derivatives Chelating agents Cacodyl compounds