Solution Conformation and Self‐Assembly of Ferrocenyl(thio)ureas

• Published in: European journal of inorganic chemistry 2017-01, Vol.2017 (2), p.433-445
• Main Authors: Hanauer, Kristina, Pham, Minh Thu, Förster, Christoph, Heinze, Katja
• Format: Article
• Language: English
• Subjects: (Thio)ureas; Anions; Assembly; Conformation analysis; Crystals; Density functional calculations; Ferrocene; Hydrogen bonds; Oxidation; Self assembly; Solid state; Solid‐state structures; Switching
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201600918

Conformations and (dis)assembly processes of ureas and thioureas are of fundamental importance in supramolecular chemistry, anion binding, or crystal engineering, both in solution and in the solid state. For sensing and switching processes a redox‐active unit, such as the ferrocene/ferrocenium couple, is especially suitable. Here, self‐assembly processes of redox‐active ferrocenyl(thio)ureas FcNHC(X)NHR [X = O, R = Fc (1), Ph (2), 1‐naphthyl (3), Me (4), Et (5); X = S, R = Fc (6), 1‐anthracenyl (7)] through hydrogen bonds – both in the solid state and in THF and CH2Cl2 solution – are reported. Special emphasis is placed on the impact of nonclassical intramolecular NH···Fe hydrogen bonds in these organometallic systems [these are absent in conventional organic (thio)ureas] on conformation and assembly. Furthermore, conformational switching and disassembly of 1–6 is induced by oxidation of 1–6 to the corresponding ferrocenium cations 1+–6+ (redox switch). Assembly processes of (thio)ureas are fundamental in anion sensing, supramolecular chemistry, and crystal engineering. The interplay of monomer conformation and hydrogen bonding, including nonclassical hydrogen bonds to iron(II), for the self‐assembly of redox‐active N,N′‐disubstituted ferrocenyl(thio)ureas is elucidated. The impact of oxidation of 1–6 on conformation and assembly is discussed.