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Crystal Structure, Thermal and Electric Behaviour of [(CH 3 ) 2 NH 2 ] 3 [As 2 Cl 9 ] and [(CH 3 ) 2 NH 2 ][AsOCl 2 ]
Author(s) -
Wojtaś M.,
Ciunik Z.,
Bator G.,
Jakubas R.
Publication year - 2002
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/1521-3749(200202)628:2<516::aid-zaac516>3.0.co;2-6
Subject(s) - crystallography , orthorhombic crystal system , thermogravimetric analysis , crystal structure , differential scanning calorimetry , chemistry , octahedron , materials science , organic chemistry , thermodynamics , physics
Single crystals of the organic‐inorganic arsenate(III): [(CH 3 ) 2 NH 2 ] 3 [As 2 Cl 9 ] and [(CH 3 ) 2 NH 2 ][AsOCl 2 ] have been grown from aqueous hydrochloric acid solution. The crystals [(CH 3 ) 2 NH 2 ] 3 [As 2 Cl 9 ] have been investigated by X‐ray diffraction (at 253 K), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dilatometric and dielectric methods. They undergo two structural phase transitions of first order at 228/235 and 298/307 K (on cooling/heating), respectively, which are classified as an "order‐disorder" type. The trigonal [(CH 3 ) 2 NH 2 ] 3 [As 2 Cl 9 ] structure (at 253 K, intermediate phase (II)) refined in the space group R3c, consists of isolated [As 2 Cl 9 ] 3‐ bioctahedral units and dimethylammonium cations hydrogen bonded to the bridging Cl atoms of the anions. The crystals of [(CH 3 ) 2 NH 2 ][AsOCl 2 ] at 100 K are orthorhombic, space group Cmca. The structure contains one‐dimensional chains formed by strong distorted [AsO 2 Cl 4 ] octahedra. The dimethylammonium cations reveal distinct disorder.