Structure and internal dynamics of 1,2-propanediammonium pentachloroantimonate (III) dichloride of formula [C3H10N2]2Cl2SbCl5

Author(s): Mohsen Ouled Mohamed Sghaier, KrystynaHolderna-Natkaniec, PiotrCzarnecki, SlaheddineChaabouni

1,2-propanediammonium pentachloroantimonate (III) dichloride, PDA, has been synthesized and characterized by theX-ray at 293K. It crystallize in the orthorhombic space group, P212121with the followingunit-cell dimensions: a=9.2610(7)A °´ , b= 10.5950(6)A °´ , c = 19.4830(1)A °´ and Z = 4. The crystal structure consists of 1,2-propanediammoniumcations, [SbCl5]2- anions and two frees atoms chlor. The Original Article ChemXpress 5(3), 089-097, (2014) ISSN(Print) : 2320 –1967 ISSN(Online) : 2320 –1975 INTRODUCTION Halogenoantimonates(III) and halogenobismuthates( III)with organic cations defined bythe general formula (RNH3 +)n(MmXn+3m)n- (whereMis SbIII, BiIII; Xis Cl, Br, I) are an interesting group of compounds due to their ferroelectric properties[1-4]. The polarityof these crystals is associatedwith phase transitions, which aremainly caused by the changes in rotationalmotions of the organic cations[2,5].These phenomena are especiallymanifested in the structures containing relativelysmallmethyl-, dimethyl-, trimethyland tetramethylammoniumcations[2,6-9].Differences in the size, symmetryand abilityto formhydrogen bonds of the various possible organic cations, togetherwith themany different possiblemetal-halogen atomconfigurations, provide a rich family of compounds. The anionic structures that have been reported so far range fromsimple isolated [MX6]3– octahedra and [MX5]2– square pyramids through isolated units containing oc- Sb III atomis coordinated bysixCl atomswhich form one-dimensional infinite chains of composition [SbCl6]3-.The compound is stabilized byintermolecularN —H….Cl hydrogen bonds. The dynamics of the proton and themolecularmotion revealed the phase transitions at the vicinity of 261Kand 355K.

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