Hydrogen bonding in 2-amino-4-methoxy-6-methylpyrimidine, 2-benzylamino-4-benzyloxy-6-methylpyrimidine and 4-benzylamino-2,6-bis(benzyloxy)pyrimidine: pi-stacked chains of fused R22(8) rings, and centrosymmetric R22(8) dimers.

Molecules of 2-amino-4-methoxy-6-methylpyrimidine, C(6)H(9)N(3)O, (I), lie on mirror planes in space group Pnma and are linked by two N-H...N hydrogen bonds [H...N = 2.26 and 2.34 A, N...N = 3.136 (2) and 3.212 (2) A, and N-H...N = 175 and 172 degrees ] into chains of edge-fused R(2)(2)(8) rings, which themselves are linked into sheets by aromatic pi-pi-stacking interactions. In 2-benzylamino-4-benzyloxy-6-methylpyrimidine, C(19)H(19)N(3)O, (II), and 4-benzylamino-2,6-bis(benzyloxy)pyrimidine, C(25)H(23)N(3)O(2), (III), the molecules are linked by paired N-H.N hydrogen bonds [H...N = 2.16 A, N.N = 3.039 (2) A and N-H...N = 165 degrees in (II); H...N = 2.15 A, N...N = 2.980 (2) A and N-H...N = 176 degrees in (III)] into centrosymmetric R(2)(2)(8) dimers, with no direction-specific interactions between these dimeric units.