The monoclinic polymorph of dimethyl­arsinic acid

摘要

The title compound, C2H7AsO2 or [As(CH3)2O(OH)], is an organic derivative of arsinic acid, and is also known by its trivial name cacodylic acid. In contrast to the first polymorph (triclinic, space group P , Z = 2), the current study revealed monoclinic symmetry (space group C2/c, Z = 8) for the second polymorph. The configuration of the tetra­hedral mol­ecule shows approximate Cs symmetry. Strong O—H⋯O hydrogen bonds connect the mol­ecules to infinite zigzag chains along [010], which are further connected by weak inter­molecular C—H⋯O contacts into a three-dimensional network.