Synthesis, crystal structures and magnetic properties of composites incorporating an Fe(II) spin crossover complex and polyoxometalatesTools Kuramochi, Satoshi, Shiga, Takuya, Cameron, Jamie M., Newton, Graham N. and Oshio, Hiroki (2017) Synthesis, crystal structures and magnetic properties of composites incorporating an Fe(II) spin crossover complex and polyoxometalates. Inorganics, 5 (3). 48/1-48/8. ISSN 2304-6740 Full text not available from this repository.
Official URL: http://www.mdpi.com/2304-6740/5/3/48
Abstract[Fe(dppOH)2]2+ (dppOH = 2,6-di(pyrazol-1-yl)-4-(hydroxymethyl)pyridine) is known to show spin crossover (SCO) behavior and light-induced excited spin state transitions (LIESST). Here, we show that the SCO properties of the [Fe(dppOH)2]2+ complex can be altered by a crystal engineering approach employing counter anion exchange with polyoxometalate (POM) anions. Using this strategy, two new composite materials: (TBA)[Fe(dppOH)2][PMo12O40] (1) and [Fe(dppOH)2]3[PMo12O40]2 (2) (TBA = tetra-n-butylammonium) have been isolated and studied by single crystal X-ray diffraction and magnetic susceptibility measurements. 1 is found to be in a high spin state at 300 K and shows no spin crossover behavior due to a dense packing structure induced by hydrogen bonding between the hydroxyl group of the dppOH ligands and the POM anions. Conversely, 2 contains two crystallographically unique Fe centers, where one is in the low spin state whilst the other is locked in a high spin state in a manner analogous to 1. As a result, 2 is found to show partial spin crossover behavior around 230 K with a decrease in the χmT value of 1.9 emu·mol−1·K. This simple approach could therefore provide a useful method to aid in the design of next generation spin crossover materials.
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