摘要: First-row transition metal complexes with d4 up to d7 electron configuration in octahedral ligand fields (and d8 six-coordinate of lower symmetry) may undergo temperature dependent high spin (HS) ⇌ low (LS) transition, provided the field strength (Δ), including symmetry contributions, becomes comparable magnitude mean pairing energy (P). At a critical Δcrit = P, levels two states cross. This is illustrated Fig. 1, where simplified Tanabe-Sugano type level diagram for d6 systems (e.g. Fe2+, Co3+) shown as an example. For weak fields, Δ Δcrit, LS state1A1g(Oh) more stable. If difference ∣Δ-P∣, or, terms thermodynamics, Gibbs free ΔG=G(HS)-G(LS), on order thermal kT, both HS and be populated equilibrium.
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sci-hub.st 参考文章(65)
Philipp Gütlich, Spin crossover in iron(II)-complexes Springer, Berlin, Heidelberg. pp. 83- 195 ,(1981) , 10.1007/BFB0111269
Mössbauer spectroscopy and its chemical applications American Chemical Society. ,(1981) , 10.1021/BA-1981-0194
Bradley C. Moore, Chemical and Biochemical Applications of Lasers ,(1980)
M. Sorai, J. Ensling, K.M. Hasselbach, P. Gütlich, Mössbauer effect study on low-spin 1A1 ⇌ high spin 5T2 transition in [Fe(2-pic)3]Cl2: II. Influence of non-coordinating solvent molecule in [Fe(2-pic)3] Cl2 · X1 X = C2H5OH, CH3OH, H2O and 2H2O principles and practice of constraint programming. ,vol. 20, pp. 197- 208 ,(1977) , 10.1016/0301-0104(77)85023-4
K. Madeja, W. Wilke, S. Schmidt, Methoden zur Darstellung von Diacido-bis-1,10-phenanthrolin-Eisen(II)-Komplexen Zeitschrift für anorganische und allgemeine Chemie. ,vol. 346, pp. 306- 315 ,(1966) , 10.1002/ZAAC.19663460511
M. Sorai, J. Ensling, P. Gütlich, Mössbauer effect study on low-spin 1A1 ⇌ high-spin 5T2 transition in tris(2-picolylamine) iron chloride I. Dilution effect in [FexZn1-x(2-pic)3]Ch2·C2H5OH principles and practice of constraint programming. ,vol. 18, pp. 199- 209 ,(1976) , 10.1016/0301-0104(76)87047-4
E. König, G. Ritter, W. Irler, S.M. Nelson, The high-spin(5T2)⇌low-spin(1A1) transition in solid dithiocyanatobis(2,2′-bi-2,thiazoline)iron(II). Hysteresis effects, debye-waller factors and crystallographic changes Inorganica Chimica Acta. ,vol. 37, pp. 169- 179 ,(1979) , 10.1016/S0020-1693(00)95540-3
D. B. Chesnut, Simple Model for Some Dense Magnetic Exciton Systems Journal of Chemical Physics. ,vol. 40, pp. 405- 411 ,(1964) , 10.1063/1.1725127
E. W. Müller, H. Spiering, P. Gütlich, On the participation of domains in the high spin (5T2) ⇄ low spin (1A1) transition in dithiocyanatobis (2,2′‐bi‐2‐thiazoline) iron (II) Journal of Chemical Physics. ,vol. 79, pp. 1439- 1443 ,(1983) , 10.1063/1.445905
Edgar Koenig, K. Madeja, 5T2-1A1 Equilibriums in some iron(II)-bis(1,10-phenanthroline) complexes Inorganic Chemistry. ,vol. 6, pp. 48- 55 ,(1967) , 10.1021/IC50047A011