A new molecular metal based on Pd(dmit)2: synthesis, structure and electrical properties of (C7H13NH)[Pd(dmit)(2)](2) (dmit(2-)=2-thioxo-1,3-dithiole-4,5-dithiolate)
T. Naito et al., A new molecular metal based on Pd(dmit)2: synthesis, structure and electrical properties of (C7H13NH)[Pd(dmit)(2)](2) (dmit(2-)=2-thioxo-1,3-dithiole-4,5-dithiolate), J MAT CHEM, 11(9), 2001, pp. 2199-2204
Air-oxidation of the acetone-acetic acid solution Of (C7H13NH)(2)[Pd(dmit)(
2)] yielded black shiny platelets of (C7H13NH)[Pd(dmit)(2)](2). The crystal
structure was characterized by a criss-cross columnar structure, which has
been often observed in M(dmit)(2)-based (M = Ni, Pd) superconductors. Alth
ough the quinuclidinium cation (C7H13NH)(+) is found to be orientationally
disordered on a 2-fold axis, the crystal exhibited metallic conductivity do
wn to similar to 40 K. Under ambient pressure the room temperature conducti
vity is around 22 S cm(-1) and the resistivity gradually decreased with dec
reasing temperature down to 200 K, where it suddenly started to decrease mo
re rapidly and kept decreasing down to similar to 40 K, where it started to
increase steeply. At ea. 200 K the structural transition occurred, yet the
crystal and molecular structures remained practically unaffected including
the cation site disorder and the strong dimerization of the Pd(dmit)(2) mo
lecules. The electrical behaviour under high pressure was rather unusual bu
t could be compared with structurally related Pd(dmit)(2)-based superconduc
tors.