An x-ray study of a crystal of new organic metal (ET)/sub 4/Hg/sub 3/Br/sub 8/

Summary form only given. An x-ray study of a crystal of new organic metal (ET)/sub 4/Hg/sub 3/Br/sub 8/ with T/sub M-D/ =20 K has been made. The crystal structure is similar to the crystals of organic superconductors (ET)/sub 4/Hg/sub 2.89/Br/sub 8/ (T/sub c/ =4.3 K) (2) and (ET)/sub 2/Hg/sub 1.41/Br/sub 8/ (T/sub c/ =2.0 K) (3). An x-ray study of crystals 1-3 allows us to assume that the anion layers consist of HgBr/sub 4//sup 2-/ ions and HgBr/sub 2/, neutral molecule alterating in the crystal in an arbitrary way. In the conducting layers of crystals 1-3, the ET are packed according to the k-type. Each cation-radical has 12 shortened S...S contacts. The atomic-atomic potentials calculations show that, the energies of intermolecular interactions in the conducting layers of crystals 1-3 are the same, 33.6 kcal/mol. At the same time, the interplanar distance between the neighbours in the ET dimer are different, being equal to 3.51(l), 3.44(l) and 3.42(3) /spl Aring/ in structural 1-3 respectively. The structure 1 is also different from 2 and 3 in stronger cation-anion interactions: the Br ... S distances are 3.59(l), 3.64(l) and 3.64(l) /spl Aring/ respectively. We believe that the discovered differences in the structure of crystals 1-3 may account for the differences in the electronductive properties.