Structure of entinostat Form B, C(21)H(20)N(4)O(3), derived using laboratory powder diffraction data and density functional techniques

The crystal structure of entinostat Form B, C(21)H(20)N(4)O(3), has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. Entinostat crystallizes in space group Pna2(1) and the crystal structure consists of inter-locking layers of entinostat mol-ecules parallel to the bc plane. A strong N-H⋯N hydrogen bond links the mol-ecules into zigzag chains propagating along the b-axis direction. The graph set for this pattern is C (1) (1)(8). Two N-H⋯O hydrogen bonds link the mol-ecules along the c-axis direction. The graph sets for this pattern are C (1) (1)(4) and C (1) (1)(7).