Two-Step Spin-Transition Iron(III) Compound with a Wide [High Spin-Low Spin] Plateau

• Published in: Inorganic chemistry Vol. 48; no. 5; pp. 2128 - 2135
• Main Authors: Tang, Jinkui, Sánchez Costa, José, Smulders, Simon, Molnár, Gábor, Bousseksou, Azzedine, Teat, Simon J, Li, Yangguang, van Albada, Gerard A, Gamez, Patrick, Reedijk, Jan
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02.03.2009
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic801973x

A new iron(III) coordination compound exhibiting a two-step spin-transition behavior with a remarkably wide [HS-LS] plateau of about 45 K has been synthesized from a hydrazino Schiff-base ligand with an N,N,O donor set, namely 2-methoxy-6-(pyridine-2-ylhydrazonomethyl)phenol (Hmph). The single-crystal X-ray structure of the coordination compound {[Fe(mph)2](ClO4)(MeOH)0.5(H2O)0.5}2 (1) determined at 150 K reveals the presence of two slightly different iron(III) centers in pseudo-octahedral environments generated by two deprotonated tridentate mph ligands. The presence of hydrogen bonding interactions, instigated by the well-designed ligand, may justify the occurrence of the abrupt transitions. 1 has been characterized by temperature-dependent magnetic susceptibility measurements, EPR spectroscopy, differential scanning calorimetry, and 57Fe Mössbauer spectroscopy, which all confirm the occurrence of a two-step transition. In addition, the iron(III) species in the high-spin state has been trapped and characterized by rapid cooling EPR studies.