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. 175358-01-7, Name is 3-Amino-6-chloropicolinamide, formurla is C6H6ClN3O. In a document, author is Deorukhkar, Neel, introducing its new discovery. Formula: C6H6ClN3O.
Tuning spin-crossover transition temperatures in non-symmetrical homoleptic meridional/facial [Fe(didentate)(3)](2+) complexes: what for and who cares about it?
The [FeN6] chromophores found in [Fe(didentate)(3)](2+) complexes, where didentate is a non-symmetrical 2-(6-membered-heterocyclic ring)-benzimidazole ligand (Lk), exist as mixtures of two geometrical mer (C-1-symmetry) and fac (C-3-symmetry) isomers. Specific alkyl-substituted six-membered heterocyclic rings connected to the benzimidazole unit (pyridines in ligands L1-L3, pyrazines in L4-L5 and pyrimidines in L6-L7) control the ligand field strength and the electron delocalization so that [Fe-II(Lk)(3)](2+) display tunable thermally-induced spin transitions in solution. Thermodynamic, spectroscopic (UV-Vis, NMR) and magnetic studies in solution demonstrate that [Fe(L6)(3)](2+) (L6 = 1-methyl-2-(pyrimidin-2-yl)-1H-benzo[d] imidazole) exhibits a close to room temperature spin transition (T-1/2 = 273(3) K) combined with a high stability formation constant (logo beta(Fe,L6)(1,3)) = 21.8(9) in acetonitrile), which makes this complex suitable for the potential modulation of lanthanide-based luminescence in polymetallic helicates. A novel method is proposed for assigning specific thermodynamic spin crossover parameters to fac-[Fe(L6)(3)](2+) and mer-[Fe (L6)(3)](2+) isomers in solution. The observed difference relies mainly on the entropic content Delta S-SCO(mer) – Delta S-SCO(fac) = 11(1) J mol(-1) K-1, which favors the spin transition for the meridional isomer. Intermolecular interactions occurring in the crystalline state largely overcome minor thermodynamic trends operating in diluted solutions and a single configurational isomer is usually observed in the solid state. Among the thirteen solved crystal structures 1-13 containing the [M(Lk)(3)](2+) cations (M = Fe, Ni, Zn, Lk = L6-L7), pure meridional isomers are observed six times, pure facial isomers also six times and a mixture (44% mer and 56% fac) is detected only once. Solid-state magnetic data recorded for the Fe-II complexes show the operation of slightly cooperative spin transitions in 7 (fac-[Fe(L6)(3)](2+)) and 12 (mer-[Fe(L7)(3)](2+)). For the meridional isomer in 6, a two-step spin state transition curve, associated with two phase transitions, is detected.
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Reference:
Pyridine – Wikipedia,
,Pyridine | C5H5N – PubChem