Amino­guanidinium hydrogen fumarate

The title compound, CH7N4 +·C4H3O4 −, is a molecular salt in which the amino­guanidinium cations and fumarate monoanions are close to planar, with maximum deviations of 0.011 (1) and 0.177 (1) Å, respectively. The crystal packing is stabilized by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds

(3E)-11,16-Dioxatricyclo[15.4.0.05,10]henicosa-1(21),3,5,7,9,17,19-heptaen-2-one

The title compound, C19H18O3, crystallizes with three molecules (A, B and C) in the asymmetric unit. The carbonyl O atom shows positional disorder over two sites in molecules A and B; the site-occupancy ratios are 0.76 (3):0.24 (3) and 0.86 (3):0.14 (3), respectively. The ethylene fragments in each molecule have an E conformation, while the C—O—C—C torsion angles indicate near planarity. The dihedral angles formed by the aromatic rings are 20.0 (1), 23.7 (1) and 16.1 (1)° for molecules A, B and C, respectively. Intramolecular C—H...O hydrogen bonds occur in each molecule

A diastereomer of methyl (1R,3′S)-1′,1′′-dimethyl-2,2′′-dioxo-2H-dispiro[acenaphthylene-1,2′-pyrrolidine-3′,3′′-indoline]-4′-carboxylate

In the title compound, C26H22N2O4, the central pyrrolidine ring adopts a twist conformation and the cyclopentane ring of the dihydroacenapthylene group adopts an envelope conformation with the spiro C atom as the flap. The naphthalene ring system of the dihydroacenaphthylene group forms dihedral angles of 83.4 (9) and 61.3 (7)°, respectively, with the mean planes of the pyrrolidine and indole rings. The crystal packing is stabilized by intermolecular C—H...O hydrogen bonds. The title compound is a diastereomer of a previously reported structure