Pressure Effect Studies on the Spin‐Transition Behavior of a Dinuclear Iron(II) Compound. Issue 5 (23rd January 2013)

• Record Type: Journal Article
• Authors: Bhattacharjee, Ashis; Roy, Madhusudan; Ksenofontov, Vadim; Kitchen, Jonathan A.; Brooker, Sally; Gütlich, Philipp
• Other Names: Murray Keith S. sponsoringEditor.; Oshio Hiroki sponsoringEditor.; Real Jose Antonio sponsoringEditor.
• Is Part Of: European journal of organic chemistry. Issue 5(2013)
• Page Start: 843
• Page End: 849
• Publication Date: 2013-01-23
• Subjects: Spin crossover -- Iron -- N li­gands -- High‐pressure chemistry -- ­Calorimetry; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejic.201201522
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: Magnetic studies into the effect of different hydrostatic pressures between ambient and 1.03 GPa on the high‐spin (HS) ⇄ low‐spin (LS) transition behavior of the dinuclear iron(II) compound [Fe II 2 (PMAT)2 ](BF4 )4 · DMF (1, PMAT = 4‐amino‐3, 5‐bis{[(2‐pyridylmethyl)amino]methyl}‐4 H ‐1, 2, 4‐triazole, DMF = N, N ‐dimethylformamide) have been carried out at 2–300 K. Under ambient pressure, the sample studied exhibits a [HS–HS] to [HS–LS] half spin transition (ST) at T ${1 \over 2}$ = 208 K without any thermal hysteresis. Increasing the pressure above 0.2 GPa causes an increase (initially rapid but above 0.5 GPa more gradual) of T ${1 \over 2}$ as well as a matching reduction in the residual high‐spin fraction at room temperature. This paper probes in detail how the increased pressure favors the stabilization of the system through a transition from the [HS–HS] state to the [HS–LS] state, although there is no evidence of the [LS–LS] state even under a pressure of 1.03 GPa and down to 2 K. This work includes magnetic measurements, a calorimetric study of the ST behavior, and an estimation of the entropy change for such a half‐ST process. The origin of [HS–HS] ⇄ [HS–LS] transition behavior, which likely lies with the rigidness of the bridging ligand, is explained in greater detail. This is consistent with significant stabilization of the [HS–LS] form by the two very rigid bridging ligands between the two Fe II centers. The role of intermolecular interactions in the stabilization of the dinuclear lattice system is established. Abstract : The spin‐transition behavior of a dinuclear Fe II compound is studied to explore how increased pressure favors the stabilization of the system through a transition from the [HS–HS] to the [HS–LS] state with no evidence of the [LS–LS] state even at the highest applied pressure (HS = high spin, LS = low spin). The origin of the spin transition lies with the rigidness of the bridging ligand.