1,3‐Dibenzoylimidazolidine‐2‐thione and 1,3‐dibenzo­yl‐3,4,5,6‐tetra­hydro­pyrimidine‐2(1H)‐thione

The title compounds, 1,3‐dibenzo­ylimidazolidine‐2‐thione, C₁₇H₁₄N₂O₂S, (I), and 1,3‐dibenzo­yl‐3,4,5,6‐tetra­hydro­pyrimidine‐2(1H)‐thione, C₁₈H₁₆N₂O₂S, (II), were obtained from the reactions of imidazolidine‐2‐thione and 1,4,5,6‐tetra­hydro­pyrimidine‐2‐thiol, respectively, with benzoyl chloride. Compounds (I) and (II) contain, respectively, imidazolidinethione [C=S = 1.6509 (14) Å] and ­pyrimidinethione [C=S = 1.6918 (19) Å] moieties bonded to two benzoyl rings. The mol­ecules of (I) exhibit C₂ symmetry, the C=S bond lying along the twofold rotation axis, while the mol­ecules of (II) have mirror symmetry (C_s). The imida­zolidine ring in (I) is essentially planar, while the pyrimidine ring in (II) adopts a boat conformation. Mol­ecules of (I) are linked by weak inter­molecular C—H⋯O inter­actions, while mol­ecules of (II) are held together by van der Waals inter­actions.