2. Materials and methods

The experiments were carried out using a single crystal of [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3] grown by slow evaporation from a mixture of hydrochloric acid containing stoichiometric CuCl2-SeO2 at room temperature in the ratio 1/2. Blue thin rectangular parallelepiped crystals were grown after vaporizing in air for 15 days approximately. The determination of [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3] formula was achieved by the crystal structure refinement approach at room temperature.

For electrical impedance measurements (in the range 1–10 KHz), a Hewlett-Packard 4192 ALF automatic bridge monitored by a HP Vectra microcomputer was used. Prepared dense translucent pellets with approximately a diameter of 8 mm and a thickness of 1–1.2 mm, covered with graphite electrodes were utilized for the measurements.

The measurement of electrical impedances were equally carried out in the range, 1–10 KHz, using a Hewlett-Packard 4192 ALF automatic bridge monitored by a HP Vectra microcomputer. For these types of experiments, dense translucent pellet samples were prepared, with a diameter of 8 mm and thickness between 1 and 1.2 mm. All the pellets were then covered with graphite electrodes prior to measurements.

A modern nondispersive Fourier Transform (FT-IR) spectrometer (Perkin-Elmer 1750 spectrophotometer IR-470) was employed for the characterization of the crystalline powders after mixing with KBr, with very notable IR-active functional groups found in the samples investigated. Scans of IR spectra were recorded in in the range 400–4000 cm<sup>1</sup> without apodization. To record Raman spectra of the solid samples for the study of the various phases, a conventional scanning Raman instrument (Horiba Jobin Yvan HR800 microcomputer system), equipped with a Spex 1403 double monochromator (with a pair of 600 grooves/mm gratings) and a Hamamatsu 928 photomultiplier detector was used. Solid materials were sampled at different temperatures for this analysis. During the recording of prominent Raman peaks, excitation radiation from the instrument was fulfilled by a coherent radiation emitted by a He-Neon laser operating at a wavelength of 633 nm, with an output laser power of 50 mW. In order to acquire high-resolution Raman spectra, the spectral resolution of the slit width varied from 3 to 1 cm<sup>1</sup> .

To study the crystal structure of [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3], an APEX II diffractometer (powder XRD) fitted with graphite-crystal monochromated Mo Kα radiation (0.71073 Å) was employed. In this study, a total of 3093 reflections were collected, among which only 2803 reflections, namely those for which I > 2σ (I), were actually used in the determination and refinement of the structure. Corrections were made for Lorentz-Polarization and absorption effects. Table 1 presents the data collection procedure and structure refinement at room temperature.

three-dimensional structure, but it may be considered as being derived from the [Cu(HSeO3)2]-

Compounds exhibiting mixed valences (like Se4+ and Cu2+) are at the center of many studies owing to their potential applications in relation to the electronic exchange. For almost all of these compounds, except [Cu(HSeO3)2], magnetic measurements have revealed the occurrence of weak ferromagnetism at low temperature (T ~ 10–20 K) for which a tentative explanation is offered for this peculiar property in agreement with other authors [8, 9]. In this study, the crystal structure of the compound [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3], herein presented, was obtained using an X-ray single structure and various spectroscopic (IR and Raman) character-

The experiments were carried out using a single crystal of [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3] grown by slow evaporation from a mixture of hydrochloric acid containing stoichiometric CuCl2-SeO2 at room temperature in the ratio 1/2. Blue thin rectangular parallelepiped crystals were grown after vaporizing in air for 15 days approximately. The determination of [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3] formula was achieved by the crystal structure refinement

For electrical impedance measurements (in the range 1–10 KHz), a Hewlett-Packard 4192 ALF automatic bridge monitored by a HP Vectra microcomputer was used. Prepared dense translucent pellets with approximately a diameter of 8 mm and a thickness of 1–1.2 mm, covered

The measurement of electrical impedances were equally carried out in the range, 1–10 KHz, using a Hewlett-Packard 4192 ALF automatic bridge monitored by a HP Vectra microcomputer. For these types of experiments, dense translucent pellet samples were prepared, with a diameter of 8 mm and thickness between 1 and 1.2 mm. All the pellets were then covered with

A modern nondispersive Fourier Transform (FT-IR) spectrometer (Perkin-Elmer 1750 spectrophotometer IR-470) was employed for the characterization of the crystalline powders after mixing with KBr, with very notable IR-active functional groups found in the samples investigated. Scans of IR spectra were recorded in in the range 400–4000 cm<sup>1</sup> without apodization. To record Raman spectra of the solid samples for the study of the various phases, a conventional scanning Raman instrument (Horiba Jobin Yvan HR800 microcomputer system), equipped with a Spex 1403 double monochromator (with a pair of 600 grooves/mm gratings) and a Hamamatsu 928 photomultiplier detector was used. Solid materials were sampled at different temperatures for this analysis. During the recording of prominent Raman peaks, excitation radiation from the instrument was fulfilled by a coherent radiation emitted by a He-Neon laser operating at a wavelength of 633 nm, with an output laser power of 50 mW. In order to acquire high-resolution Raman spectra, the spectral resolution of the slit width varied

type structure.

30 Chalcogen Chemistry

ization, as well as dielectric measurements.

2. Materials and methods

approach at room temperature.

graphite electrodes prior to measurements.

from 3 to 1 cm<sup>1</sup>

.

with graphite electrodes were utilized for the measurements.

A three-dimensional Patterson synthesis approach was used to determine the selenium atoms positions in the compound. On the one hand, the Fourier function allowed for the localization of the chlorine (Cl), copper (Cu), and oxygen (O) atoms. On the other hand, the hydrogen atoms were localized from a difference Fourier synthesis and introduced as fixed contributors. Conversely, all the non-hydrogen atoms were typically assigned anisotropic thermal displacements. The structure solution and refinement were carried out using SHELX programs [10, 11]. The bond lengths and angles are given in Table 2.


Table 1. Crystal structure data and experimental conditions for the structure determination of [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3].


the octahedral site of Cu(2) are typically consistent with the value +2.7, confirming the presence of selenium Se4+ and cuprite Cu2+ in the same site. It is also observed that the blue single crystal [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3] crystallizes in the orthorhombic system, space group Pbn21. Structurally, the crystal structure of [Cu0.332Se0.582(HSeO3)2CuCl3(H2O)3] represents a new type of structure for complexes of hydrogen selenites (Figure 1). The building blocks [Cu0.335Se0.582(HSeO3)2] and [CuCl3(H2O)3], hereunder drawn, are arranged to form layers in the structure parallel to the (001) plane between which the lone pairs E are located (Figure 2). Due to the stereochemical activity of the lone pairs E, Se has very asymmetric

The Characterization of a Newly Layered Bimetallic Hydrogen Selenite Copper-Selenium: Synthesis and Structure

http://dx.doi.org/10.5772/intechopen.76310

33

Spatially, the high anisotropic distribution of anions observed around each cation is characteristically of a strong stereochemical activity of their electron lone pair E for the Se1 and Se3 atoms. The consequence for the coordination polyhedral is the description of a distorted SeO3 triangular pyramid, in which the SedO(7) and SedO(8) are marginally longer than the other SedO bonds (Table 2). Thereof, the lone pair E so directed to constitute the fourth vertex of an

The OdSedO with angles of values 98(2) and 102(2) formed from SedO chemical bonds are situated on one side of the Se atom, whereas the other side is hitherto a "dead" zone around

Figure 1. Perspective view of the [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3] unit cell content.

coordination polyhedral SeO3 pyramids.

SeO3E tetrahedron (Figure 3).

Symmetry code: a: –x + 1/2, y + 1/2, z; b: –x + 3/2, y + 1/2, z; c: –x + 3/2, y 1/2, z; d: –x + 1/2, y 1/2, z; e: –x + 1, y + 2, z + 1/2.

Table 2. Interatomic distances for [Cu0.335Se0.582(HSeO3)2CuCl3(H2O)3] samples (this study).
