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Crystal structures and magnetic properties are determined for two novel compounds, [1-(4'-iodobenzyl)-pyridinium][M(mnt)(sub 2)] (mnt(super 2-) = maleonitriledithiolate, M = Ni (1) or Cu (2)). It is concluded that the structural transition of M=Ni is driven by spin-lattice interaction, as crystal Cu (S = 0) does not exhibit a structural transition.

A nonmagnetic compound, [NO2BzPy][Au(mnt)2] (NO2BzPy+ = 1-(4'-nitrobenzyl)pyridinium; mnt2- = maleonitriledithiolate), was synthesized and characterized structurally, which is isostructural with [NO2BzPy][Ni(mnt)2] that is a quasi-one-dimensional magnet and possesses a spin-Peierls-like transition with J = 192 K in the gapless state and spin energy gap = 738 K in the dimerization state, respectively. Further, ten nonmagnetic impurity doped compounds with a formula [NO2BzPy][AuxNi1-x(mnt)2] (x = 0.01−0.73) were prepared and investigated by crystal structural determinations and magnetic susceptibility measurements. The nonmagnetic doping causes the suppression of the spin transition with an average rate of 221(12) K/percentage of dopant concentration. From the plots of χm−T, the transition collapse (the characteristic of the transition is the sudden drop of χm upon cooling, and the disappearance of this characteristic is considered as the criterion for the transition collapse) is estimated at around x > 0.27. In heavier doped system x = 0.49, the spin gap vanishes and a gapless phase is achieved again. [ABSTRACT FROM AUTHOR]