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Show 85 college of science The purpose of this research was to synthesize and characterize analogs of [FeII(TCNE•-)- (NCMe)2]+[FeIIICl4]- where TCNE is tetracyanoethylene and NCMe is acetonitrile. [FeII(TCNE•-)- (NCMe)2]+[FeIIICl4]- is a molecule-based magnet that orders as a ferrimagnet below 90 K, the magnetic ordering temperature (Tc). The Tc is the temperature at which a compound undergoes a transition from being ordered magnetically to being in a disordered paramagnetic phase. This compound was synthesized by mixing FeCl2(NCMe)2 and TCNE with a 2:1 mol ratio in dichloromethane. The analog was synthesized by mixing FeCl2(NCMe)2 and TCNQF4 (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquin-onedimethane) with a 2:1 mol ratio in dichloromethane. TCNQF4 was chosen because of its similar reduction potential and its similarity in structure to TCNE. The product was dark green whereas the starting materials were orange and white indicating that a reaction took place. Reduced TCNQF4 is green so it is likely that the TCNQF4 was reduced in the reaction. AC susceptibility (χ ' and χ '') and remnant magnetization measurements were performed. The most linear part of the onset of χ '' and the most linear part of the onset of the remnant magnetization were used to do a linear regression to find the Tc. The Tc was found to be 77.2 ± 0.5 K in both measurements. The existence of χ '' indicated that the compoound was either ferromagnetic or ferrimagnetic, because antiferromagnets lack a χ ''. Since [FeII(TCNE•-)(NCMe)2]+[FeIIICl4]- ordered ferrimagnetically, it is likely that the analog also orders ferrimagnetically. The compound showed magnetic field induced hysteretic behavior. At 2 K, the compound had a coercive field of 4780 ± 25 Oe. The coercive field is the magnitude of an opposing magnetic field needed to reduce the magnetization of a compound to zero. SYNTHESIS OF AN [FeII(TCNE•-) (NCMe)2]+[FeIIICl4]- ANALOG Kevin Siegel (Joel S. Miller, Jack Dasilva) Department of Chemistry University of Utah UNDERGRADUATE RESEARCH ABSTRACTS Kevin Siegel Joel S. Miller |
