Crystal structures of 3-meth­oxy-4-{[5-(4-meth­oxy­phen­yl)-1,3,4-oxa­diazol-2-yl]meth­oxy}benzo­nitrile and N-(4-{[5-(4-chloro­phen­yl)-1,3,4-oxa­diazol-2-yl]meth­oxy}phen­yl)acetamide

The title compounds, C(18)H(15)N(3)O(4) and C(17)H(14)ClN(3)O(3), are heterocyclic 1,3,4-oxa­diazole derivatives which differ from each other in the groups attached to the carbon atoms: a meth­oxy­phenyl ring and a benzo­nitrile group in (I) and a chloro­phenyl ring and an acetamide group in (II). Short intra­molecular C—H⋯O hydrogen bonds occur in both mol­ecules. The crystal structure of (I) features C—H⋯N hydrogen bonds, while in the crystal structure of (II), N—H⋯N, C—H⋯N and C—H⋯O hydrogen bonds are observed.