One of the major reasons for studying chemical kinetics is to use measurements of the macroscopic properties of a system, such as the rate of change in the concentration of reactants or products with time. 50681-25-9, Name is 4-Pyridazinecarboxylic Acid, formurla is C5H4N2O2. In a document, author is Saldia, Marianela, introducing its new discovery. SDS of cas: 50681-25-9.
Electronic and Photophysical Properties of Re-I(CO)(3)Br Complexes Modulated by Pyrazolyl-Pyridazine Ligands
The direct reaction of a series of substituted (1H-pyrazol-1-yl)pyridazine (L-I: 6-(1H-pyrazolyl)pyridazine; L-II: 3-chloro-6-(1H-pyrazole-1-yl)-pyridazine; L-III: 6-(1H-3,5-dimethylpyrazolyl)pyridazine-3-carboxylic acid; L-IV: 3,6-bis-N-pyrazolyl-pyridazine; and L-V: 3,6-bis-N-3-methylpyrazolyl-pyridazine) with the bromotricarbonyl(tetrahydrofuran)rhenium(I) dimer leads to the monometallic complexes [(L-X)Re(CO)(3)Br] (I-V), which displays a nonregular octahedral geometry around the Re-I center and a fac-isomerism for the carbonyl groups, whereas pyridazine and pyrazolyl rings remain highly coplanar after coordination to rhenium. Cyclic voltammetry shows one irreversible oxidation and one irreversible reduction for each compound as measured in N, N-dimethylformamide. Oxidation ranges from 0.94 V for III to 1.04 V for I and have been attributed to the Re-I/Re-II couple. In contrast, the reductions are ligand centered, ranging from -1.64 V for II to -1.90 V for III and V. Density functional theory calculations on the vertical one electron oxidized and one electron reduced species, using the gas-phase optimized geometry for the neutral complex confirm this assignment. Compounds I-V show two absorption bands, one around 410 nm (metal-to-ligand charge transfer (MLCT), Re-d pi -> pi*) and the other at similar to 300 nm (intraligand, pi -> pi*). Excitation at 400 nm at 77 K leads to unstructured and monoexponential emission with large Stokes shift, whose maxima vary between 570 (III) and 636 (II) nm. The quantum yields for these emissions in solution are intensified strongly going from air to argon equilibrated solution. Singlet oxygen quantum yields change from 0.03 (III) to 0.21 (IV). These data are consistent with emission from (MLCT)-M-3. The emission undergoes a bathochromic shift when R-1 is a pi-donating group (Cl or N-pyrazolyl) and a hypsochromic shift for a pi-acceptor (COOH). The bimolecular emission quenching rate constant by triethylamine (TEA) for II, IV, and V is 1.09, 0.745, and 0.583 x 10(8) M-1 s(-1), respectively. Photolysis in dichloromethane-CO2 saturated solution with TEA as a sacrificial electron donor leads in all cases to formic acid generation.
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Reference:
Pyridazine – Wikipedia,
,Pyridazine | C4H4N2 – PubChem