Crystal Structure and Characterization of CsH5(AsO4)2: A New Cesium Pentahydrogen Arsenate, and Comparison with CsH5(PO4)2 and RbH5(AsO4)2

✍ Scribed by H. Naı̈li; T. Mhiri; J. Jaud

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 482 KB
• Volume: 161
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9218

✦ Synopsis

Chemical preparation and X-ray single-crystal, vibrational, and calorimetric studies of CsH 5 (AsO 4 ) 2 are described. The new compound crystallizes in the monoclinic system P2 1 /c with cell parameters a ‫؍‬ 10.983(1) A s , b ‫؍‬ 7.943(1) A s , c ‫؍‬ 9.844(1) A s , ‫؍‬ 96.15(1)3, V ‫؍‬ 853.82(6) A s 3 , Z ‫؍‬ 4, and cal ‫؍‬ 3.235 g cm ؊3 . The re5nement of data leads to R 1 ‫؍‬ 0.0396 and WR 2 ‫؍‬ 0.0809 for 2377 observed re6ections (I > 2 (I)) re5ned with 122 parameters. The structure is di4erent from RbH 5 (AsO 4 ) 2 (orthorhombic) and similar to CsH 5 (PO 4 ) 2 (monoclinic). The atomic arrangement can be described as layered organization of isolated arsenate tetrahedra; interleaved cesium cations ensure the cohesion of the structure. As in all atomic arrangements, we can observe the formation of an in5nite network of anions connected by strong H bonds (2.436(4)+2.597(5) A s ). The hydrogen atoms were located from di4erence maps and the short contact (2.436(4) A s ), which is not astride any symmetry element, is of the type O+H2O asymmetrical. The Raman and infrared spectra of CsH 5 (AsO 4 ) 2 recorded at room temperature in the frequency ranges 10+1000 cm ؊1 and 250+4000 cm ؊1 , respectively, con5rm the presence of two independent AsO 3 ؊ 4 groups in the crystal. An assignment of all the bands is given. Di4erential scanning calorimetry shows that the title compound does not exhibit any phase transition in the range 123+473 K.