Copper(II) Cubane Complexes Built from Electro‐ and Photosensitive β‐Aminovinyl Trifluoromethyl Ketone Ligands

Abstract

A new family of [Cu 4 L 4 ] cubane complexes have been synthesized by the self-assembly of Cu II salts and β-aminovinyl trifluoromethyl ketone ligands. The resulting polynuclear architectures were especially designed to exhibit magnetic properties arising from the metallic cubane architecture as well as electro-or photosensitive properties arising from the ligands. The optical and electrochemical behaviours of the compounds were measured in solution to confirm that the properties of the free ligands were retained within the elaborated complexes. DFT investigations of the organic moieties [a] Université Claude 5058 Scheme 2. Designed β-aminovinyl trifluoromethyl ketone ligands L1H 2 -L4H 2 .

Quenching of Fluorescence in Bodipy‐Derived Trifluoromethyl Enaminone Ligands upon Coordination to Copper(II)

“…The four short Cu–O,N bond lengths in the {NO 3 } square plane range from 1.881(7) to 1.952(7) Å, whereas the oxygen atom coordinated in the apical position exhibits a longer Cu–O bond length that is equal to 2.395(7) Å (Table 2). All these bond lengths are in good agreement with those previously reported in the literature 7,8. The cubane core appears slightly distorted with two types of Cu ··· Cu distances: four short [3.11(1) Å] and two long ones [3.17(1) Å].…”

“…A good agreement with the experimental data for compound B is obtained with two sets of parameters: (a) J 1 = +0.93(3) cm –1 , J 2 = +16.89(2) cm –1 , g = 2.09(1), zJ = –0.225(4) cm –1 and R = 4.3 × 10 –3 ; and (b) J 1 = +20.56(3) cm –1 , J 2 = –10.29(2) cm –1 , g = 2.02(1), zJ = –0.122(5) cm –1 , and R = 4.6 × 10 –3 (Figure S1 in the Supporting Information). Despite fit (a) being the best in terms of quality, the values of exchange parameters in fit (b) correspond better to the ones previously reported on the [Cu 4 ] cubane series with similar ligands 7,28…”

“…Since the reversibility of this step is found in CH 2 Cl 2 , it seems that the Bodipy + · radical cation is chemically unstable in DMF. A second broad irreversible oxidation step (around +1.15 V for L1 H and A and around +1.12 V for L2 H 2 and B ) can be found in DMF (Figure 5b, d) and around +1.60 V in CH 2 Cl 2 for all four compounds, likely owing to the formation of the unstable radical cation of the enaminone moiety 6b,7. The reversible reduction step of the Bodipy core is observed between –1.63 and –1.86 V in both DMF (Figure 5a, c) and CH 2 Cl 2 (Figure S2 in the Supporting Information).…”

“…The ability of enaminones to coordinate with a variety of transition metals is well known and allows, for example, the successful preparation of metallomesogens for liquid‐crystal applications,3 catalysts for C–C and C–O coupling reactions,4 and also some boron chelate complexes that exhibit fluorescence properties 5. In some of our previous studies, we demonstrated the ability of trifluoromethyl bi‐, tri‐, and tetradentate enaminone ligands to coordinate copper(II) and to give access (1) to mononuclear complexes with interesting redox properties6 and (2) tetranuclear complexes with cubane‐type architecture, which exhibit ferromagnetic interactions between paramagnetic metal centers 7. Such cubanes are appropriate molecular precursors towards the elaboration of single‐molecule magnets (SMMs) 8…”

Dinuclear Zn(II) and tetranuclear Co(II) complexes of a tetradentate N2O2 Schiff base ligand: Synthesis, crystal structure, characterization, DFT studies, cytotoxicity evaluation, and catalytic activity toward benzyl alcohol oxidation

“…Among polynuclear transition metal complexes, tetranuclear clusters with cubane‐like M 4 O 4 core have been widely studied and have received considerable attention . However, reports on cobalt clusters of the type Co 4 O 4 ‐containing cubane structure are scarce …”