STRUCTURE OF 2,9-DIMETHYL-1,10-PHENANTHROLINE HEMIHYDRATE

C14H12N2.1/2H2O, M(r) = 217.27, tetragonal, I4(1/a), a = 14.258 (3), c = 22.286 (4) angstrom, V = 4531 (3) angstrom 3, Z = 16, D(x) = 1.274 (1) g cm-3, Mo K-alpha radiation, lambda = 0.71073 angstrom, mu = 0.74 cm-1, F(000) = 1840, T = 297 K, R = 0.041 for 1196 unique observed reflections with I > 2-sigma(I). Pairs of dimethylphenanthroline molecules related by a two-fold axis are bridged by water molecules lying on the twofold axis and H bonded to one of the N atoms in each molecule. The H bonds are long and far from linear: O-H 1.06 (4), H...N 2.03 (4), O...N 3.020 (3) angstrom; O-H...N 154 (3)degrees. This is presumably a consequence of the approximately parallel arrangement of the two phenanthroline molecules in the (phen)2.H2O complex, which are tilted 4.7 (1)degrees with respect to each other; the atoms in one molecule are 3.50 to 3.81 angstrom from the plane of the other molecule. On the other side of the phenanthroline is another phenanthroline related by a center of symmetry with the atoms of one molecule 3.41 to 3.45 angstrom from the plane of the other molecule. The phenanthroline molecule has close to 2mm symmetry, but the individual C6 rings are tilted about 1-degrees with respect to each other.