Crystal structures, magnetic and dielectric features of two new isostructural one-dimensional platinum-bis-dithiolene molecular solids

摘要

Two new one-dimensional (1-D) molecular solids, [CH2 = CH-BzPy][Pt(mnt)(2)] (1) and [CH2 = CH-BzPy-d(5)] [Pt(mnt)(2)] (2) where CH2 = CH-BzPy-d(5)(+)= 1-N-(4-vinylbenzyl) pyridinium-d(5) and mnt(2-) = maleonitrile-dithiolate, were synthesized and characterized. A structural phase transition undergoes with T-C approximate to 335 K in the crystals of 1 and 2, which were confirmed by variable-temperature magnetic susceptibility and DSC measurements. Crystals oft and 2 are isostructural in both high- and low-temperature phases. Besides the strong similarity in crystal structures, they show quite analogous magnetic and dielectric features. Above To the magnetic behavior is failed to follow the S = 1/2 Heisenberg linear chain model; below To a spin gap is opened for 1 and 2. The thermally-assisted dielectric relaxation occurs above ca. 280K for 1 and 2, and this relaxation process is related to the dipole motion of the disordered CH2=CH groups in the cation under an ac electrical field. (C) 2014 Elsevier B.V. All rights reserved.