A new molecular magnetic semiconductor based on tetrathiafulvalene (ttf) and oxamato ligand (opba): [ttf]2[Cu(opba)]·H2O

• Autor(a) principal: Dias,Mauro C.
• Data de Publicação: 2010
• Outros Autores: Stumpf,Humberto O., Mambrini,Raquel V., Matencio,Tulio, Sansiviero,Maria T. C., Knobel,Marcelo
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532010000700015
• topic: tetrathiafulvalene; molecular magnetism; semiconductor; oxamato ligand; molecular spintronics

An oxamato-based compound of formula [ttf]2[Cu(opba)]·H2O, with ttf = tetrathiafulvalene and opba = ortho-phenylenebis(oxamato), has been prepared and characterized. The complex was obtained by metathesis from (ttf)3(BF4)2 and (Bu4N)2[Cu(opba)] in acetonitrile at room temperature. The UV-Vis-NIR spectrum reveals the presence of the radical cation in two forms, (ttf•+) and (ttf•+)2 dimer. The electronic transport properties of [ttf]2[Cu(opba)]·H2O were studied by impedance spectroscopy (IS) and linear voltammetry (LV), and show a typical semiconductor behavior. The EPR spectra exhibit two superposed lines corresponding to electron spins of CuII ions and ttf•+ radical cations. The dc magnetic properties show a room temperature value of the χMT product close to that expected for three uncoupled S = ½ spins and a value of 0.13 emu K mol-1 at low temperature (4 K). The χMT vs. T curve was fitted and the best model consists of a term for a (ttf•+)2 dimer (Bleaney-Bowers, leading to J2 = -186 cm-1) and a second term related to an antiferromagnetic {Cu···ttf•+} chain (J1 = -10.1 cm-1).