Bidentate and Tetradentate β‐Aminovinyl Trifluoromethylated Ketones and Their Copper(II) Complexes: Synthesis, Characterization and Redox Chemistry

Abstract

Keywords: Electrochemistry / UV/Vis spectroscopy / Copper / FluorineNew polyfunctional bidentate and tetradentate trifluoromethylated enaminone ligands that bear redox-active and photosensitive moieties were synthesized in moderate to good yields and their coordination chemistry with copper(II) was examined. The crystal structures revealed the formation of mononuclear Cu II complexes with all ligands, where the metal ion is located in almost perfect to distorted square planar environments. The deviation from an ideal square

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

“…The mononuclear complex A is built from two deprotonated L1 – bidentate ligands and one Cu II ion, which is located in a distorted ML 4 square‐plane {N 2 O 2 } environment (see Figure 1a) and coordinated to the enaminone pincer part of ligands. Cu–O,N bond lengths are similar and range from 1.910(5) to 1.965(5) Å, which is in good agreement with what was found previously for similar complexes 6b. The distortion of the copper environment can be evaluated by different parameters:19 (1) The average N,O–Cu–N,O angles are equal to 146.8 and 94.7°, which differs from the theoretical values for a square plane, 180 and 90°, respectively; (2) the ω parameter (angle between planes formed by the enaminone moiety including the central atom) is equal to 47.3°; and (3) the β parameter (half of the value of the mean trans ‐ligand–metal–ligand) is equal to 73.4°.…”

“…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).…”

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

“…The β‐aminovinyl trifluoromethyl ketones (enaminones) L2H 2 – L4H 2 (Scheme ) were prepared in moderate unoptimized yields in three straightforward steps: acetalization of suitable methyl ketones A – C , trifluoroacetylation of dimethyl acetals D ,36 E 35b and F 35b by using a combination of trifluoroacetic anhydride (TFAA, 2 equiv.) and pyridine (4 equiv.)…”

“…and pyridine (4 equiv.) in anhydrous dichloromethane and O/N substitution of the resulting methoxyvinyl (trifluoromethyl) ketones G ,36 H 35b and I 35b with ethanolamine in anhydrous acetonitrile (Scheme ).…”

“…Compounds A and C are commercially available. Compounds B , E , F , H and I have been recently described in the literature 35b. Compounds D and G were prepared as described in the literature 36 .…”