Triphenylamine Derivatives Containing Nitronyl Nitroxide and Iminyl Nitroxide-Syntheses, Characterization, Crystal Structures and Magnetic Studies
Abstract
New triphenylamine derivatives 1, 2, 3, and 4 were synthesized and characterized by IR, FAB-MS, EPR and EA. All of them displayed similar absorption and fluorescence spectra except compound 1, for which a possible explanation was proposed. Quasi-reversible oxidation waves at about 0.76 V (vs. SCE) and 1.1 V for nitronyl nitroxide and iminyl nitroxide respectively as well as irreversible one at about 1.5 V for triphenylamine group were detected with cyclic voltammetry for compounds 1, 2, 3 and 4. Crystal structures of 2 and 4 were determined by X-ray diffraction analysis. Their crystal data are as follows: for 2: monoclinic, C2/c, a = 1.69914 (4), b = 1.37435(5), c = 1.24621(5) ran, β= 106.553(2)°, V = 2.7896(2) nm3 Z = 4; for 4: orthorhombic, Pbca, a = 1.95970(6), b = 1.33096(4), c = 4.84691(14) nm, V = 12.6421(7) nm3, Z = 8. Magnetic studies indicated that all of them showed antiferromagnetic properties in solid state, but with strong intermolecular spin-spin coupling as indicated by the relatively large values of 6, in particular for 4 (θ = −12 K). Possible spin-spin interaction mechanism was suggested based on the crystal structures of 2 and 4.
