Crystal structures of 4,7-phenanthrolino-5,6 : 5 ',6 '-pyrazine tetrahydrate and 1,4,5,8,9,12-hexaazatriphenylene dihydrate

The crystal structures of 4,7-phenanthrolino-5,6:5' ,6'-pyrazine tetrahydra te (I) and 1,4,5,8,9,12-hexaazatriphenylene dihydrate (II) have been determ ined from low temperature (173 K) x-ray single crystal diffraction data. I crystallizes in the triclinic system, space group P (1) over bar with a = 1 1.2687(6), b = 12.4766(6), c = 12.7068(7) Angstrom, alpha = 113.4740(10), b eta = 91.605(2), gamma = 114.587(2)degrees, V = 1449.33(13) Angstrom(3), an d Z = 4. II crystallizes in the orthorhombic system, space group Pca2(1) wi th a = 18.187(2), b = 9.2576(11), c = 6.9672(8) Angstrom, V = 1173.0(2) Ang strom(3), and Z = 4. In both structures the planar heterocyclic molecules s tack with interplanar distances down to 3.3 Angstrom, which is consistent w ith self-pi-complexation. The crystal water molecules provide links between the columns of stacked molecules through hydrogen bonds. In each compound the N-C bond lengths fall into two distinct groups (mean values 1.330(3) vs 1.361(1) Angstrom in I and 1.320(3) vs 1.357(5) Angstrom in II), as do the C-C bonds of the central phenyl rings (1.411(4) vs 1.467(1) Angstrom in I and 1.405(5) vs 1.458(4) Angstrom in II).