Exploring Tuning of Structural and Magnetic Properties by Modification of Ancillary β‑Diketonate Co-ligands in a Family of Near-Linear Tetranuclear Dy^III Complexes

Three tetranuclear Dy^III complexes, [Dy₄­(LH)₂­(CH₃­OH)₄­(acac)₆] (<b>1</b>), [Dy₄­(LH)₂­(CH₃­OH)₄­(hmacac)₆]·​2CH₃OH (<b>2</b>), and [Dy₄­(LH)₂­(CH₃­OH)₄­(dpacac)₆]·​2CHCl₃·​2CH₃OH·​2H₂O (<b>3</b>), have been synthesized and characterized [LH₄ = (2<i>E</i>,​<i>N</i>′<i>E</i>)-<i>N</i>′-(2,3-dihy­droxy­benzyl­idene)-2-(hy­droxy­imino)­propane­hydra­zide; acacH = acetyl­acetone; hmacacH = 2,2,6,6-tetra­methyl-3,5-heptane­dione; dpacacH = dibenzoyl­methane]. The structural elucidation of these complexes reveals two types of Dy^III centers in terms of the number of ancillary β-diketonate co-ligands coordinated to the metal centers. Detailed magnetic studies have been carried out on <b>1</b>–<b>3</b> which reveal a slow relaxation of magnetization at low temperatures. The relaxation of complexes <b>2</b> and <b>3</b> is distributed in three temperature ranges: lower temperature process, transition range, and higher temperature process. In the higher temperature range, the best fitting of the data for <b>2</b> yields τ₀ = (6.3 ± 3.6) × 10^–6 s and <i>U</i>_eff = (23.8 ± 4.0) K, and for <b>3</b>, τ₀ = (9.4 ± 5.9) × 10^–6 s, <i>U</i>_eff = (29.0 ± 6.3) K

Stepwise Reversible Oxidation of <i>N</i>‑Peralkyl-Substituted NHC–CAAC Derived Triazaalkenes: Isolation of Radical Cations and Dications

Herein, the isolation and characterization of <i>N</i>-peralkyl-substituted NHC–CAAC derived triazaalkenes in three oxidation states, neutral, radical cation, and dication, are reported. Cyclic voltammetry has shown the reversible electronic coupling between the first and second oxidation to be Δ<i>E</i>_1/2 = 0.50 V. As a proof-of-principle, to demonstrate the electron-rich nature of the triazaalkene, it was shown that it can be used as an electron donor in the reduction of an aryldiazonium salt to the corresponding arene