The synthesis of bis(formazanate) zinc complexes is described. These complexes have well-behaved redox-chemistry, with the ligands functioning as a reversible electron reservoir. This allows the synthesis of bis(formazanate) zinc compounds in three redox states in which the formazanate ligands are reduced to "metallaverdazyl" radicals. The stability of these ligand-based radicals is a result of the delocalization of the unpaired electron over four nitrogen atoms in the ligand backbone. The neutral, anionic, and dianionic compounds (L2 Zn(0/-1/-2)) were fully characterized by single-crystal X-ray crystallography, spectroscopic methods, and DFT calculations. In these complexes, the structural features of the formazanate ligands are very similar to well-known β-diketiminates, but the nitrogen-rich (NNCNN) backbone of formazanates opens the door to redox-chemistry that is otherwise not easily accessible.
The bond energy of the unsupported Au-Au bond in the Au(ii) dimer [(C(∧)N(∧)C)Au]2 and the difference between Au(III)-OH and Au(III)-H bond enthalpies have been determined experimentally by electrochemical methods, with Au-OH and Au-H complexes showing unexpected differences in their reduction pathways, supported by DFT modelling.
ABSTRACT:We report the first known examples of triazolederivatised cymantrene complexes (η 5 -[4-substituted-triazol-1-yl]cyclopentadienyl tricarbonyl manganese(I), obtained via a "click" chemical synthesis, bearing either a phenyl, 3-aminophenyl or 4-aminophenyl moiety at the 4-position of the triazole ring. Structural characterization data using multinuclear NMR, UV-vis, ATR-IR and mass spectrometric methods are provided as well as crystallographic data for (η 5 -[4-phenyltriazol-1-yl]cyclopentadienyl tricarbonyl manganese(I) and (η 5 -[4-(3-aminophenyl)triazol-1-yl]cyclopentadienyl tricarbonyl manganese(I). Cyclic voltammetric characterization of the redox behaviour of each of the three cymantrene-triazole complexes is presented together with digital simulations, in situ infra-red spectroelectrochemistry and DFT calculations to extract the associated kinetic and thermodynamic parameters. The trypanocidal activity of each cymantrene-triazole complex is also examined and found to be more active than cymantrene alone.
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