STABLE MOLECULAR-METAL [PD(DDDT)(2)]AG1.54BR3.50 - SYNTHESIS, CRYSTAL-STRUCTURE, TRANSPORT-PROPERTIES AND ELECTRONIC BAND-STRUCTURE

The synthesis, crystal and electronic band structures as well as condu cting properties of the new stable molecular metal [Pd(dddt)(2)]Ag1.54 Br3.50 (dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolato) are reported. T he crystal structure contains layers of donor cations alternating with layers of silver bromide complex anions along the a axis of the unit cell. The Ag and Pr atoms are disordered in the anion layer. The condu cting layers contain uniform stacks of the translationally equivalent Pd(dddt)(2) cations along the c-axis with a Pd ... Pd distance of 4.15 7(2) Angstrom. Within the cation layers there are shortened interstack S ... S contacts (3.49(3) and 3.56(3) Angstrom). The temperature depe ndence of the resistivity exhibits metallic behaviour down to 1.3 K. T he resistivity anisotropy (rho(a)/rho(bc)) at room temperature is abo ut 600 and does not change considerably when decreasing the temperatur e down to 4.2 K. The origin of the metallic conductivity of [Pd(dddt)( 2)]Ag1.54Br3.50 as well as the stability of this salt with respect to metal-to-insulator transitions is explained on the basis of tight bind ing band structure calculations.