The monoclinic polymorph of dimethyl-arsinic acid

Abstract

The title compound, C 2H 7AsO 2 or [As(CH 3) 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 P1̄ , Z = 2), the current study revealed monoclinic symmetry (space group C2/c, Z = 8) for the second polymorph. The configuration of the tetra-hedral molecule shows approximate C s symmetry. Strong O - H⋯O hydrogen bonds connect the molecules to infinite zigzag chains along [010], which are further connected by weak inter-molecular C - H⋯O contacts into a three-dimensional network.