10.1021/om500039a.s001 Rajkumar Jana Rajkumar Jana Biprajit Sarkar Biprajit Sarkar Sabine Strobel Sabine Strobel Shaikh M. Mobin Shaikh M. Mobin Wolfgang Kaim Wolfgang Kaim Jan Fiedler Jan Fiedler Electrochemical Evidence for Hemilabile Coordination of 1,3-Dimethyllumazine to [1,1′-Bis(diorganophosphino)ferrocene]copper(I) American Chemical Society 2014 voltammetric steps BF coordination lability DML ligand spectroelectrochemical measurements Electrochemical Evidence PF UV ferrocene units 2.25 Å. Reversible oxidation Hemilabile Coordination hemilabile coordination Cu complex Structure determinations IR 2014-09-22 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Electrochemical_Evidence_for_Hemilabile_Coordination_of_1_3_Dimethyllumazine_to_1_1_Bis_diorganophosphino_ferrocene_copper_I_/2253181 The complex cations [Cu­(dippf)­(DML)]<sup>+</sup> ([<b>1</b>]<sup>+</sup>) and [Cu­(dppf)­(DML)]<sup>+</sup> ([<b>2</b>]<sup>+</sup>), where dippf = 1,1′-bis­(diisopropylphosphino)­ferrocene, dppf = 1,1′-bis­(diphenylphosphino)­ferrocene, and DML = 1,3-dimethyllumazine, were prepared and crystallized as BF<sub>4</sub><sup>–</sup> or PF<sub>6</sub><sup>–</sup> salts. Structure determinations of the tetrafluoroborates revealed asymmetric O<sup>4</sup>,N<sup>5</sup> chelation of DML to copper­(I) with longer Cu–O bonds of about 2.25 Å. Reversible oxidation to [<b>1</b>]<sup>2+</sup> and [<b>2</b>]<sup>2+</sup> proceeds at the ferrocene units, while reduction leads to the neutral radical complexes [<b>1</b>] and [<b>2</b>] 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.