Central nervous system drugs: Low temperature X-ray structures of (I) the base 5-(2,3-dichlorophenyl)-2,4-diamino-6-fluoromethyl-pyrimidine (4030W92) and (II) 5-(2,6-dichlorophenyl)-1-H-2,4-diamino-6-methyl-pyrimidine methanesulphonic acid salt (227C89)

The X-ray crystal structures of (I), the base 4030W92, 5-(2,3- dichlorophenyl)-2,4-diamino-6-fluoromethyl-pyrimidine, C11H 9Cl2FN4, and (II) 227C89, the methanesulphonic acid salt of 5-(2,6-dichlorophenyl)-1-H-2,4-diamino-6-methyl-pyrimidine, C 11H11Cl2N4 • CH 3O3S, have been carried out at low temperature. A detailed comparison of the two structures is given. Structure (I) is non-centrosymmetric, crystallizing in space group P21 with unit cell a = 10.821(3), b = 8.290(3), c = 13.819(4) Å, β = 105.980(6)°, V = 1191.8(6) Å3, Z = 4 (two molecules per asymmetric unit) and density (calculated) = 1.600 mg/m3. Structure (II) crystallizes in the triclinic space group ̄ with unit cell a = 7.686(2), b = 8.233(2), c = 12.234(2) Å, α = 78.379(4), β = 87.195(4), γ = 86.811(4)°, V = 756.6(2) Å3, Z = 2, density (calculated) = 1.603 mg/m3. Final R indices [I > 2sigma(I)] are R1 = 0.0572, wR2 = 0.1003 for (I) and R1 = 0.0558, wR2 = 0.0982 for (II). R indices (all data) are R1 = 0.0983, wR2 = 0.1116 for (I) and R1 = 0.1009, wR2 = 0.1117 for (II). 5-Phenyl-2,4 diaminopyrimidine and 6-phenyl-1,2,4 triazine derivatives, which include lamotrigine (3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine), have been investigated for some time for their effects on the central nervous system. The three dimensional structures reported here form part of a newly developed data base for the detailed investigation of members of this structural series and their biological activities. © 2008 Springer Science+Business Media, LLC.