Synthesis, crystal structure, thermal and dielectric properties of tetrapropylammonium tetrachloroantimonate(III)

The new organic-inorganic compound, tetrapropylammonium tetrachloroantimonate(III), [N(C3H7)4][SbCl4], crystallizes at room temperature in the monoclinic system (P21/c space group) with the following unit cell parameters: a=18.1973(5) Å, b=15.7225(4) Å, c=15.7225 (3) Å, β=91.65(1)° and Z=4. The atomic arrangement can be described by a stacking of organic-inorganic layers along a direction. Each layer is made up by two types of tetrapropylammonium cations and two types of distorted tetrachloroantimonate(III) anions. Differential scanning calorimetry studies indicate a presence of two order-disorder phase transitions located at 343 K and 363 K. Besides, an analysis of the dielectric constants ε', ε″ and loss tangent (tan(δ)) versus temperature, at several frequencies, shows a distribution of relaxation times. This relaxation is probably due to the reorientational dynamics of alkyl chains.