Syntheses, characterization, and reactivity of copper complexes with camphor-like tetramethylguanidine ligands

• Published in: Inorganica Chimica Acta 2018-09, Vol.481, p.171-175
• Main Authors: Wern, Miriam, Ortmeyer, Jochen, Josephs, Patrick, Schneider, Tobias, Neuba, Adam, Henkel, Gerald, Schindler, Siegfried
• Format: Article
• Language: English
• Subjects: Alkylation; Camphor; Chemical reactions; Coordination compounds; Copper; Copper compounds; Ligands; Reaction kinetics
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2017.09.020

Based on camphor (top) guanidine based ligands NH2-TMG (left) and TMG-TMG (right) were used to support formation of bis-µ-oxido copper complexes. [Display omitted] •It was possible to synthetically modify a camphor derivative by guanidine groups.•The two new ligands applied supported formation of quite stable bis-µ-oxido copper complexes.•These findings are promising to investigate the potential of these complexes for enantioselective oxidation reactions. The reactions of dioxygen with copper(I) complexes with the ligands (1R,3S)-1,2,2-trimethylcyclopentane-3-amino-1-(N,N,N′,N′-tetramethyl-guanidine) and (1R,3S)-1,2,2-trimethylcyclopentane-1,3-Bis(N,N,N′,N′-tetramethyl-guanidine) have been investigated. The new ligands are based on a camphor-like structure and contain alkylated guanidine units for stabilization of copper “dioxygen” adduct complexes. Bis-µ-oxido dicopper(III) complexes were detected spectroscopically using low-temperature stopped-flow techniques and a kinetic analysis suggested that the formation of a transient superoxido copper complex was rate determining.