title: Bis(2,9-dimethyl-1,10-phenanthrolin-1-ium) hydrogen (S,S)-tartrate nona-hydrate.
abstract: The asymmetric unit of the title compound, 2C(14)H(13)N(2) (+)·2C(4)H(5)O(6) (-)·9H(2)O, contains two cations and two anions in addition to nine mol-ecules of water. Each of the hydrogen tartrate anions is hydrogen bonded to itself by translation along [100] in a head-to-tail fashion via a short hydrogen bond with donor-acceptor distances of 2.473 (4) and 2.496 (4) Å. A large number of inter-molecular O-H⋯O, N-H⋯O and C-H⋯O hydrogen-bonding inter-actions, as well as π-π stacking [centroid-centroid distances in the range 3.642 (3) to 3.866 (3) Å], play an important role in the crystal structure.
authors.forename: Zohreh
authors.initials: Z
authors.lastname: Derikvand
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead