Synthesis, X-Ray Structure, Magnetic Properties, and a Study of Intra/Intermolecular Radical-Radical Interactions of a Triradical TEMPO Compound.
A novel triradical compound with a P=S core and three branches functionalized with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radicals is synthesized and characterized by IR, (1) H NMR, (31) P NMR, and EPR spectroscopy and MALDI-TOF mass spectrometry, and its chemical structure is confirmed by X-ray diffraction analysis. The triradical shows neither spin exchange interactions between its radical units nor detectable dipolar interactions. This is consistent with the separation between the radical units found in its X-ray diffraction structure, and discounts the existence of intramolecular interactions. This conclusion is confirmed by an EPR concentration study. The concentration at which intermolecular interactions start to appear is determined (5×10(-3)  m) and this concentration should be taken into account as a higher concentration limit when studies on intramolecular radical-radical interactions in polyradicals with similar structure are required. SQUID magnetometry analysis of the compound shows antiferromagnetic interactions between the spin carriers of different molecules; that is, antiferromagnetic intermolecular interactions.
Institut de Ciència de Materiales de Barcelona (ICMAB-CSIC), Campus UAB s/n, E-08193, Cerdanyola del Vallès, Spain.|CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain.
Vega
V
Lloveras
Institut de Ciència de Materiales de Barcelona (ICMAB-CSIC), Campus UAB s/n, E-08193, Cerdanyola del Vallès, Spain.|CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain.|Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo, 1, 35131, Padova, Italy.
Elena
E
Badetti
Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Center for Chemistry and Biomedicine, Innrain 80-82, A-6020, Innsbruck, Austria.
Klaus
K
Wurst
Institut de Ciència de Materiales de Barcelona (ICMAB-CSIC), Campus UAB s/n, E-08193, Cerdanyola del Vallès, Spain. j.vidal@icmab.es.|CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain. j.vidal@icmab.es.
José
J
Vidal-Gancedo
D003497:Cyclic N-Oxides / Q000737:chemistry*; D008280:Magnetics; D008958:Models, Molecular; D014961:X-Ray Diffraction
D003497:Cyclic N-Oxides; C003959:TEMPO
EPR spectroscopy; X-ray diffraction; magnetic properties; radicals; through-space interactions