title: The monoclinic polymorph of dimethyl-arsinic acid.
abstract: The title compound, C(2)H(7)AsO(2) or [As(CH(3))(2)O(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[Formula: see text], Z = 2), the current study revealed monoclinic symmetry (space group C2/c, Z = 8) for the second polymorph. The configuration of the tetra-hedral mol-ecule shows approximate C(s) symmetry. Strong O-H⋯O hydrogen bonds connect the mol-ecules to infinite zigzag chains along [010], which are further connected by weak inter-molecular C-H⋯O contacts into a three-dimensional network.
authors.affiliation: Nelson Mandela Metropolitan University, Summerstrand Campus, Department of Chemistry, University Way, Summerstrand, PO Box 77000, Port Elizabeth 6031,  South Africa.
authors.forename: Richard
authors.initials: R
authors.lastname: Betz
authors.forename: Cedric
authors.initials: C
authors.lastname: McCleland
authors.forename: Harold
authors.initials: H
authors.lastname: Marchand
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