title: N-(2-Methyl-phen-yl)maleamic acid.
abstract: In the title compound, C(11)H(11)NO(3), the conformation of the N-H bond is anti to the C=O bond in the amide segment, while it is syn to the ortho-methyl group in the phenyl ring. In the maleamic acid unit, the amide C=O bond is anti to the adjacent C-H bond, while the carboxyl C=O bond is syn to the adjacent C-H bond. The C=O and O-H bonds of the acid group are in the relatively rare anti position to each other. This is an obvious consequence of the intra-molecular O-H⋯O hydrogen bond donated to the amide carbonyl group. The ortho-substituted phenyl ring makes a dihedral angle of 12.7 (1)° with the mean plane of the maleamic acid unit. In the crystal structure, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into zigzag chains parallel to [001]. These chains are further linked into sheet by weak π-π inter-actions [centroid-centroid distance = 3.425 (2) Å].
authors.forename: B Thimme
authors.initials: BT
authors.lastname: Gowda
authors.forename: Miroslav
authors.initials: M
authors.lastname: Tokarčík
authors.forename: K
authors.initials: K
authors.lastname: Shakuntala
authors.forename: Jozef
authors.initials: J
authors.lastname: Kožíšek
authors.forename: Hartmut
authors.initials: H
authors.lastname: Fuess