Above room temperature spin transition in a series of iron(II) bis(pyrazolyl)pyridine compounds

作者：Madhu N T; Salitros Ivan; Schramm Frank; Klyatskaya Sveflana; Fuhr Olaf; Ruben Mario^*

来源：Comptes Rendus Chimie, 2008, 11(10): 1166-1174.

DOI：10.1016/j.crci.2008.06.015

• Iron(II)
• Bispyrazolylpyridine ligands
• Spin transition

We report on the synthesis of a series of iron(II) compounds of the general composition [FeII(L)(2)](ClO(4))(2) center dot nCH(3)CN (where L is 4-iodo-2,6-bis(pyrazol-1-yl)pyridine (L(1)), 4-(4'-hydroxyphenyl)-2,6-bis(pyrazol-1-yl)-pyridine (L(2)), 4-(4'-trimethylsilylethynyl)-2,6-bis(pyrazol-1-yl)pyridine (L(3)), and 4-ethynyl-2,6-bis(pyrazol-1-yl)pyridine (L(4))). The compounds [Fe(II)(L)(2)](ClO(4))(2)center dot nCH(3)CN (1-4; n = 0 for 1, 2, and 4; n = 2 for 3) were characterised by single crystal X-ray diffraction studies, MALDI-TOF mass spectrometry and elemental analysis. Temperature-dependent magnetic studies reveal different types of spin transition behaviour. Compounds [Fe(II)(L(1))2](ClO(4))(2) (1) and [Fe(II)(L(2))(2)](ClO(4))(2) (2) show above or near room temperature spin transition with T(1/2) = 333 and 281 K. The investigations of compound [Fe(II)(L(3))(2)](ClO(4))(2)center dot 2CH(3)CN (3) elucidate a more complex magnetic behaviour with spin transition of half of the involved iron(II) centres at temperatures above 140 K and ferromagnetic exchange coupling of the remaining high-spin centres below 125 K. Finally, compound [Fe(II)(L(4))(2)](ClO(4))(2) (4) is completely blocked in the diamagnetic low-spin state in the temperature range from 5 to 3 80 K. To cite this article: N.T. Madhu et al., C.R. Chimie 11 (2008).

• 出版日期2008-10