Chelated Fischer carbene complexes of annulated thiophenes: synthesis, structure and electrochemistry

• Published in: Dalton transactions : an international journal of inorganic chemistry 2020-11, Vol.49 (43), p.15339-15354
• Main Authors: Lamprecht, Zandria, Malan, Frederick P, Fernández, Israel, Lotz, Simon, Bezuidenhout, Daniela I
• Format: Article
• Language: English
• Subjects: Cartesian coordinates; Coordination compounds; Crystallography; Data collection; Density functional theory; Electrochemistry; Infrared spectroscopy; NMR; Nuclear magnetic resonance; Synthesis; Thiophenes
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d0dt03298k

Two (thieno[3,2- b ]thiophene) and three annulated thiophenes (dithieno[2,3- b ;3′,2′- d ]thiophene and dithieno[3,2- b ;2′,3′- d ]thiophene) were employed as building blocks to synthesize linear or semi-circular chelated mononuclear biscarbene and dinuclear tetracarbene complexes. The electronic properties of the annulated thienylene chelated carbene complexes were investigated by cyclic voltammetry experiments and compared to non-chelated Fischer-type monocarbene complexes. Density functional theory (DFT) calculations were used to assign the redox events and to probe the extent of electron delocalisation as well as the possibility of electronic (intramolecular metal-metal) communication as a result of intervalence. The differences of these electronic properties in the conjugated chelated carbene complexes are compared to chelated carbene compounds without a linear conjugated pathway. The effect of curved or linear band annulated thiophene structures of chelated carbene complexes on conjugation pathways and electronic properties.