title: Charge-transfer complexes of 4-(dimethylamino)pyridine with 2,4-, 3,4- and 3,5-dinitrobenzoic acid.
abstract: In the three title crystal structures 4-(dimethylamino)pyridinium 2,4-dinitrobenzoate, (I), 4-(dimethylamino)pyridinium 3,4-dinitrobenzoate, (II), and 4-(dimethylamino)pyridinium 3,5-dinitrobenzoate, (III), all C(7)H(11)N(2)(+).C(7)H(3)N(2)O(6)(-), the ions are connected by an N-H.O hydrogen bond. Dihedral angles between the pyridine and phenyl rings are 69.9 (1), 26.7 (1) and 56.2 (1) degrees in (I), (II) and (III), respectively. Donor-acceptor pi-pi stacking is observed in (II) and (III), but not in (I).
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Hosomi
authors.forename: S
authors.initials: S
authors.lastname: Ohba
authors.forename: Y
authors.initials: Y
authors.lastname: Ito