MOLECULAR CONDUCTORS FROM NEUTRAL-RADICAL CHARGE-TRANSFER SALTS - PREPARATION AND CHARACTERIZATION OF AN IODINE-DOPED HEXAGONAL PHASE OF 1,2,3,5-DITHIADIAZOLYL ([HCN2S2](CENTER-DOT))

Sublimation of 1,2,3,5-dithiadiazolyl in vacuo affords a triclinic pha se of the dimer [HCN2S2](2). The crystals belong to the space group <o ver bar>P1, a=8.816(3), b=13.940(2), c=14.403(3) Angstrom a=3 116.830( 14),beta=98.64(3), gamma 99.18(3)degrees, FW=212.4 (for [HCN2S2](2). [ N-2](0.08) Z=6. The crystal structure consists of stacked dimers, with three dimers per asymmetric unit. Pairs of asymmetric units, related by an inversion center, generate a pinwheel motif consisting of six di mers. The columnar structure associated with these pinwheels forms clo se-packed sets of ''molecular tubes''. Cosublimation of the radical th e presence of iodine in the mole ratio (HCN2S2:I=5:1) yields an iodine -doped hexagonal phase of composition [HCN2S2](6)[I](1.1). Crystals of this material belong to the space group P6(1), a=b=14.132(16), c=3.35 2(5) Angstrom, FW=128.20, Z=6. The crystal structure consists of sixfo ld pinwheels in which-the now evenly spaced HCN2S2 rings form a spiral about the 6(1) axis. The iodine atoms lie within the columnar cavity of the pinwheels in a disordered array wrapped tightly about the sixfo ld screw axis. The single-crystal conductivity of the doped material i s 15 S cm(-1) at room temperature. Raman spectroscopic and magnetic su sceptibility measurements on the doped material are reported.