Electrochemical Evidence for Hemilabile Coordination of 1,3-Dimethyllumazine to [1,1 '-Bis(diorganophosphino)ferrocene]copper(I)

• Published in: Organometallics
• Main Authors: Jana, R., Sarkar, B., Strobel, S., Mobin, S. M., Kaim, W., Fiedler, J. (Jan)
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: electrochemistry; metal complexes; crystal structure; DML
• Online Access: https://doi.org/10.1021/om500039a; http://hdl.handle.net/11104/0238723

The complex cations [Cu(dippf)(DML)](+) ([1](+)) and [Cu(dppf)(DML)](+) ([2](+)), where dippf = 1,1'-bis(diisopropylphosphino)ferrocene, dppf = 1,1'-bis(diphenylphosphino)ferrocene, and DML = 1,3-dimethyllumazine, were prepared and crystallized as BF4- or PF6- salts. Structure determinations of the tetrafluoroborates revealed asymmetric O-4,N-5 chelation of DML to copper(I) with longer Cu-O bonds of about 2.25 angstrom. Reversible oxidation to [1](2+) and [2](2+) proceeds at the ferrocene units, while reduction leads to the neutral radical complexes [1] and [2] with the unpaired electron localized on the DML ligand. The occurrence of two voltammetric steps for the one-electron-reduction process is attributed to a two-species equilibrium caused by the hemilabile coordination of DML. Electrochemical and spectroelectrochemical measurements (UV-vis, IR) reveal increased coordination lability of the reduced complexes and their slow fragmentation.