Unique structural topolgies involving metal-metal and metal-sulfur interactions: salts of [Ni(C_3S_5)_2]~(x-) with cis-anti-cis-dicyclohexyl-18-crown-6 complexed counter ions

摘要

Preparation by electrocrystallisation has been carried out for the salts [Rb(anti-dchyl-18-c6)]_2]1, [Rb(anti-dchyl-18c6)][Ni(dmit)_2]2, [Cs(anti-dchyl- 18c6)]_2(Ni(dmit)_2]3 and [Cs(anti~dchyl-l8c6)_(1.5)][Nidmit_(2]_64 (anui-dchyl-18c6 = cis-anti~cisdicyclohexyl1 S-crown-6, dmit = C3S~). Salts 1 and 3 involve the planar dianionic nickel complex sandwiched by two metal-crown units. This leads to short Rb~+...Ni and RV. S interactions in I and the shortest recorded Cs~+ ... Ni distance of 3.47 A in 3, presumably stabilised by the four surrounding S atoms at 3.73-4,44 A. DFT calculations on the dianionic salts 1 and 3 indicate an essentially electrostatic interaction between the [Ni(dmit)_2)2 complex and the Rb - or Cs~ ion and show frontier orbitals qualitatively similar to those previously derived from EHMO calculations on molecular conductors containing (Ni(dmit)2J. Salt 2 consists of non-stacked nickel complexes arranged in chains linked by s... Rb~ interactions through the terminal sulfurs with the Rb~ ion placed exactly within the plane of the crown oxygens. Magnetic susceptibility measurement indicated weak antiferromagnetic interactions Salt 4 shows a 2-D sheet of nickel complexes stacked in a herringbone arrangement separated by layers of counter ions complexed by the crowns in a disordered manner with the anion : cation ratio of 6:1 uniquely high among [Ni(dmit)_2]~(x-)salts. Salt 4 displays semiconductor behaviour with #sigma#_(RT)=10~(-2)S cm~(-1).