A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, SDS of cas: 2926-30-9, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 2926-30-9, Name is Sodium trifluoromethanesulfonate, molecular formula is CF3NaO3S. In a Article, authors is Chang, Hsiu-Rong£¬once mentioned of 2926-30-9
(Tetrakis(2-pyridylmethyl)ethylenediamine)iron(II) perchlorate, the first rapidly interconverting ferrous spin-crossover complex
The preparation and characterization of the first FeII spin-crossover complex that interconverts between high- and low-spin states at a rate faster than the 57Fe Moessbauer time scale is reported. [Fe(tpen)](ClO4)2¡¤2/3H 2O crystallizes in the monoclinic space group C2/c, which at 298 K has a unit cell of a = 40.87 (2) A, b = 9.497 (4) A, c = 23.946 (9) A, and beta = 108.42 (4) with Z = 12 and at 358 K the unit cell is characterized by a = 41.00 (2) A, b = 9.517 (5) A, c = 24.21 (1) A, and beta = 109.46 (4) with Z = 12. The hexadentate ligand tpen is tetrakis(2-pyridylmethyl)ethylenediamine. The refinements were carried out with 3110 (2.58sigma) and 2221 (2.58sigma) observed reflections at 298 and 358 K, respectively, to give R = 0.073 and Rw = 0.076 at 298 K and R = 0.082 and Rw = 0.082 at 358 K. At both temperatures there are two crystallographically different [Fe(tpen)]2+ cations. One of these two cation sites has a greater high-spin content, as evidenced by Fe-ligand atom bond lengths and trigonal distortions which are greater than those found at the other cation site. The Fe-N bond lengths and trigonal distortion increase for both cations as the temperature is increased from 298 to 358 K. Solid-state magnetic susceptibility data show that the critical temperature, Tc, where there are equal amounts of high- and low-spin complexes, is Tc = 365 K. Faraday balance data for this same perchlorate salt in DMF solution give Tc = 363 K. The similarity of these solid- and solution-state Tc values and the susceptibility data taken for the pure solid and solid solutions in the isostructural Zn2+ complex definitively show that the spin-crossover cations in [Fe(tpen)](ClO4)2¡¤2/3H 2O experience no appreciable intermolecular interactions. Each cation acts independently in a high-/low-spin equilibrium. The 57Fe Moessbauer spectrum exhibits only one quadrupole-split doublet for each cation up to the highest temperature (350 K) investigated. Thus, this is the first FeII spin-crossover complex that interconverts in the solid state between high- and low-spin states at a rate that is faster than the Moessbauer time scale. A careful analysis of the changes in the structure of the [Fe(tpen)]2+ cation as a function of temperature together with angular overlap calculations suggest that it is the increase in Fe-N bond lengths together with an increase in the trigonal distortion that leads to the fast rate of spin-state interconversion in [Fe(tpen)]2+. The steric constraints introduced by the hexadentate ligand lead to a relatively large trigonal distortion lowering the energy of triplet excited states (3T1 and/or 3T2). This then leads to greater spin-orbit interaction of the 1A low-spin state with components of the 5T2 high-spin state, and a greater rate of interconversion results. Additional evidence supporting the presence of fluxional distortions of [Fe(tpen)]2+ along a trigonal twisting coordinate is presented in the form of variable-temperature 1H NMR data. In solution [Fe(tpen)]2+ exhibits a very fast rate (>600 s-1) of enantiomerization. Finally, the preparation and properties (Tc > 400 K) of [Fe(tpen)](ClO4)2 are given. This non-hydrated complex crystallizes in the monoclinic space group P21/c, which at 298 K has a unit cell characterized by a = 17.865 (3) A, b= 9.878 (1) A, c = 17.213 (4) A, and beta= 110.01 (2) with Z = 4. This structure was refined with 3031 (2.58sigma) observed reflections to give R = 0.049 and Rw = 0.053. The trigonal twist found for the cation is in keeping with magnetic susceptibility data indicating that this nonhyrated complex is totally low spin at 298 K.
I hope this article can help some friends in scientific research. I am very proud of our efforts over the past few months and hope to 2926-30-9, help many people in the next few years.SDS of cas: 2926-30-9
Reference£º
Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI