Methyl 2‐(4‐ferrocenylbenzamido)thiophene‐3‐carboxylate and ethyl 2‐(4‐ferrocenylbenzamido)‐1,3‐thiazole‐4‐acetate, a unique ferrocene derivative containing a thiazole moiety

The conformations and hydrogen bonding in the thiophene and thia­zole title compounds, [Fe(C 5 H 5 )(C 20 H 14 NO 3 S)], (I), and [Fe(C 5 H 5 )(C 19 H 17 N 2 O 3 S)], (II), are discussed. The sequence (C 5 H 4 )–(C 6 H 4 )–(CONH)–(C 4 H 2 S)–(CO 2 Me) of rings and moieties in (I) is close to being planar; all consecutive inter­planar angles are less than 10°. An intra­molecular N—H⋯O=C ester hydrogen bond [graph set S (6), N⋯O = 2.768 (2) Å and N—H⋯O = 134 (2)°] effects the mol­ecular planarity, and aggregation occurs via hydrogen‐bonded chains formed from inter­molecular C ar —H⋯O=C ester/amide inter­actions along [010], with C⋯O distances ranging from 3.401 (3) to 3.577 (2) Å. The thia­zole system in (II) crystallizes with two mol­ecules in the asymmetric unit; these differ in the conformation along their long mol­ecular axes; for example, the inter­planar angle between the phenyl­ene (C 6 H 4 ) and thia­zole (C 3 NS) rings is 8.1 (2)° in one mol­ecule and 27.66 (14)° in the other. Inter­molecular N—H⋯O=C ester hydrogen bonds [N⋯O = 2.972 (4) and 2.971 (3) Å], each augmented by a C phenyl­ene —H⋯O=C ester inter­action [3.184 (5) and 3.395 (4) Å], form motifs with graph set (7) and generate chains along [100]. The amide C=O groups do not participate in hydrogen bonding. Compound (II) is the first reported ferrocen­yl‐containing thia­zole structure.