Georgiev,and
D. Stoilova
Journal of the UniversityV.ofKaradjova,
Chemical M.
Technology
Metallurgy, 47, 3, 2012, 303-310
PREPARATION, X-RAY POWDER DIFFRACTION AND VIBRATIONAL SPECTRA
OF (NH4)2Be(IO3)4·2H2O AND K2Be(IO3)4·2H2O
V. Karadjova1, M. Georgiev1, D. Stoilova2
1
University of Chemical Technology and Metalurgy
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail:[email protected]
E-mail:[email protected]
2
Institute of General and Inorganic Chemistry
Bulgarian Academy of Sciences
“Akad. G. Bonchev” str., bl.11, 1113, Sofia, Bulgaria
E-mail:[email protected]
Received 05 May 2012
Accepted 22 June 2012
ABSTRACT
The solubility in the three-component MeIO3-Be(IO3)2-H2O (Me = K, NH4+) systems at 25°C is studied by the
method of isothermal decrease of supersaturation. It has been established that double salts, K2Be(IO3)4·2H2O and
(NH4)2Be(IO3)4·2H2O, crystallized from the ternary solutions in wide concentration ranges. The X-ray powder diffraction
as well as the vibration spectroscopic studies reveal that the title compounds are isostructural.
Comparatively strong hydrogen bonds are formed in the potassium compound analogically to other beryllium
compounds owing to the strong Be-OH2 interactions (synergetic effect) as deduced from the wavenumbers of νOD of
matrix-isolated HDO molecules (isotopically dilute samples). The formation of weaker hydrogen bonds in the ammonium
salt (bonds of moderate strength) than that in the potassium one is due to the decreasing proton acceptor capability of the
IO3- ions. The latter are involved in hydrogen bonds with NH4+ ions additionally to those with water molecules and as a
result of these molecular interactions the proton acceptor strength of the iodate ions decreases as compare to that of the
same ions in the potassium compound (anti-cooperative effect). The normal vibrations of other entities (IO3- ions and BeO4
tetrahedra (skeleton vibrations)) are also discussed. A hypothesis is made that probably at least two crystallographically
different iodate ions exist in the structures. The water librations couple intensively with both the translatory modes of the
BeO4 tetrahedra and the normal modes of the iodate ions, thus resulting in small values of isotopic ratios νR(H2O)/νR(D2O)
(close to 1).
Keywords: potassium beryllium iodate dihydrate, ammonium beryllium iodate dihydrate, solubility diagrams,
vibrational spectroscopy, hydrogen bond strength.
INTRODUCTION
Our interest in beryllium compounds is determined
by their promising physical properties. For example, the
synthesis and some properties of different beryllium iodate crystal hydrates (protonated and deuterated) are
widely discussed in previous papers of one of the authors
[1-8]. Recently, the preparation and the thermal behavior of the double beryllium iodates, K2Be(IO3)4·2H2O
and (NH4)2Be(IO3)4·2H2O, have been reported [7,8].
Thermal dehydration and decomposition schemes are
proposed and some kinetic parameters (E* and A) are
calculated. The infrared spectra of both compounds in
the spectral regions of the iodate ions are briefly
commented.
In this paper we present and discuss the solubility diagrams of the three-component MeIO3-Be(IO3)2 H2O (Me = K, NH4+) systems at 25°C. The vibrational
303
Journal of the University of Chemical Technology and Metallurgy, 47, 3, 2012
spectra (infrared and Raman) are commented with respect to the strength of the hydrogen bonds formed by
the water molecules and to the normal modes of the
different entities in the structures (IO3- ions and BeO4
tetrahedra (skeleton vibrations)).
EXPERIMENTAL
Be(IO3)2·4H2O was prepared by neutralization of
beryllium oxide with HIO3 solution at 60-70°C. Then
the solution was filtered, concentrated at 50-60°C, and
cooled to room temperature. The crystals were filtered,
washed with alcohol and dried in air. Commercial KIO3
and NH4IO3 were used. The solubility in the threecomponent MeIO3 - Be(IO3)2 - H2O (Me = K, NH4+)
systems at 25°C was studied by the method of isothermal decrease of supersaturation. Preliminary experiments show that the equilibrium between the liquid and
solid phases was reached in two days. The compositions
of the liquid and solid phases were analyzed, as follows:
the IO 3 - ion concentrations were determined
iodometrically; the K+ and NH4+ ion concentrations
were determined gravimetrically after precipitation as
K[B(C6H5)4] and NH4[B(C6H5)4]. The Be2+ ion content
was taken to be the difference in weights of both compounds. The compositions of the solid phases were identified by means of X-ray powder diffraction and infrared
spectroscopy as well. Deuterated samples of the double
salts, K2Be(IO3)4·2H2O and (NH4)2Be(IO3)4·2H2O, were
prepared from solutions containing a different ratio of
H2O/D2O using the same crystallization procedure. The
reagents used were “p.a.” quality (Merck).
The Raman spectra of the compounds were recorded using a Spex Industries 1404 double monochromator (resolution 2 cm-1) in the region of 1000-100 cm-1.
An argon laser (excitation wavelength: 488 nm) was used.
The sample was measured in glass capillary employing
the backscattering geometry. X-ray powder diffraction
spectra were collected within the range from 5° to 40°
2è with a step 0.02° 2è and counting time 35 s/step on
a Bruker D8 Advance diffractometer with Cu Ká radiation and SolX detector. The infrared spectra were recorded on a Bruker model IFS 25 Fourier transform
interferometer (resolution < 2 cm-1) at ambient temperature using KBr discs as matrices. Ion exchange or
other reactions with KBr have not been observed (infrared spectra using Nujol mulls were also measured).
304
RESULTS AND DISCUSSION
The solubility diagrams of the MeIO3-Be(IO3)2-H2O
(Me = K, NH4+) systems at 25°C are shown in Fig. 1 (the
respective experimental data are summarized in Tables 1
and 2). Three crystallization fields are observed in the
diagrams – two very narrow crystallization fields of the
simple salts, KIO3, NH4IO3 and Be(IO3)2·4H2O, and wide
crystallization fields of double salts - K2Be(IO3)4·2H2O
and (NH4)2Be(IO3)4·2H2O. The potassium compound
crystallizes from solutions containing 16.10 % mass beryllium iodate and 0.78 % mass potassium iodate up to solutions
containing 0.79 % mass beryllium iodate and 5.18 % mass potassium iodate. The chemical analysis of the double salt
shows 43.61 % mass beryllium iodate and 52.02 % mass potassium iodate (theoretical content – 43.29 % mass Be(IO3)2
and 51.64 % mass KIO3). (NH4)2Be(IO3)4·2H2O crystallizes
from solutions containing 16.17 % mass beryllium iodate
Fig. 1. Solubility diagrams of the KIO3-Be(IO3)2-H2O and
NH4IO3-Be(IO3)2-H2O systems at 25°C.
V. Karadjova, M. Georgiev, D. Stoilova
Table 1. Solubility in the KIO3 - Be(IO3)2 - H2O system at 25°C.
Composition of the solid phases
Liquid phase, % mass
Wet solid phase, % mass
Be(IO3)2
17.81
15.97
16.14
16.10
9.17
4.09
2.46
0.94
0.79
0.65
0.06
-
KIO3
0.86
0.99
0.78
0.24
1.77
0.83
0.78
5.18
5.01
8.19
8.64
Be(IO3)2
KIO3
57.11
25.20
30.11
28.73
18.98
14.37
IR, XRD
IR, XRD
IR, XRD
26.83
18.98
1.45
-
33.59
70.37
93.90
-
Be(IO3)2·4H 2O
“−“
Be(IO3)2·4H 2O + K2Be(IO3)4 ·2H 2O
K2Be(IO3)4 ·2H2O
“−“
“−“
“−“
“−“
“−“
KIO3 + K2Be(IO3)4·2H 2O
KIO3
“−“
Table 2. Solubility in the NH4IO3 - Be(IO3)2 - H2O system at 25°C.
Liquid phase, % mass
Be(IO3)2
17.81
16.41
16.24
16.17
13.82
11.96
10.11
7.18
4.11
4.02
3.18
-
NH4IO3
1.35
1.44
1.39
2.03
1.64
1.83
2.43
3.34
3.26
2.57
3.96
Wet solid phase, % mass
Be(IO3)2
NH4IO3
47.21
24.56
31.67
27.41
IR, XRD
36.89
35.48
IR, XRD
29.67
34.56
14.24
65.68
0.78
82.81
-
and 1.39 % mass ammonium iodate up to solutions containing 4.11 % mass beryllium iodate and 3.34 % mass ammonium
iodate (the chemical analysis of the double salt shows 46.58
% mass beryllium iodate and 49.03 % mass ammonium iodate; theoretical content – 45.96 % mass Be(IO3)2 and 49.42
% mass NH4IO3). The formation of double compounds in
wide concentration ranges is due to strong complex formation processes occurring in the ternary solutions, thus
leading to the formation of mixed aqua iodate complexes
of the Be2+ ions.
The X-ray powder diffraction patterns of
K2Be(IO3)4·2H2O and (NH4)2Be(IO3)4·2H2O are shown
in Fig. 2 (d-spacing, hkl and relative intensities are given
in Table 3). It is readily seen from Fig. 2 and the data in
Table 3 that both compounds are isostructural.
The normal vibrations of the free NH4+ and IO3ions in aqueous solutions are reported to appear, as fol-
Composition of the solid phases
Be(IO3)2 ·4H2O
“−“
Be(IO 3)2 ·4H2O + (NH 4)2Be(IO3)4 ·2H2O
(NH 4)2Be(IO3)4 ·2H2O
“−“
“−“
“−“
“−“
“−“
NH4IO3 + (NH4)2Be(IO3)4 ·2H2O
NH4IO3
“−“
lows: for the NH4+ tetrahedral ions – ν1(A1) = 3040 cm-1,
ν2(E) = 1680 cm-1, ν3(F) = 3145 cm-1, ν4(F) = 1400 cm-1;
for the pyramidal IO3- ions – ν1(A1) = 779 cm-1, ν2(A1) =
390 cm-1, ν3(E) = 826 cm-1, ν4(E) = 330 cm-1 [9]. The
BeO4 tetrahedra are known to exhibit lattice modes (skeleton vibrations) – ν12 , ν22 , ν32 and ν42 in the range of
540, 250–300, 700–900 and 350 cm -1, respectively
[10,11]. On going into solid state the normal modes are
expected to shift to higher or lower frequencies due to
different intra- and intermolecular interactions.
The interpretation of the vibrational spectra of
the compounds studied has to be made with a great deal
of precaution due to two main reasons: (i) the crystal
structures of the double salts are not reported in the
literature and (ii) an intensive coupling between the
normal modes of the IO3- ions, the translatory modes of
the beryllium tetrahedra and the water librations oc-
305
Journal of the University of Chemical Technology and Metallurgy, 47, 3, 2012
608
K2Be(IO3)4·2H2O
1625
988 956
470
806
(NH4)2Be(IO3)4·2H2O
Transmittance (%)
Intensity (a.u.)
K2Be(IO3)4·2H2O
867
824
725
751
785
779 775
600
964
1626
465
1455
806
1426
1415
716
824
15
20
25
30
35
2Θ (degree)
40
45
50
55
60
1600
680
867
(NH4)2Be(IO3)4·2H2O
10
683
785
1200
775
800
737
749
400
-1
Wavenumber (cm )
Fig. 2. X-ray powder diffraction patterns of K2Be(IO3)4·2H2O
and (NH4)2Be(IO3)4·2H2O.
Fig. 3. Infrared spectra in the regions of 1700-400 cm-1 of
K2Be(IO3)4·2H2O and (NH4)2Be(IO3)4·2H2O.
curs and as a result the normal vibrations of the different entities could not be recognized precisely. The assignments of the infrared and Raman bands discussed
in this paper are made according to those reported for
Be(IO3)2·4H2O [3], Be(IO3)2 [4] and for iodate crystal
hydrates of Mg, Co, Ni [12]. It is reported that the
symmetric modes ν1 and ν2 of the iodate ions appear at
higher frequencies than the asymmetric ones ν3 and ν4,
respectively [3, 4, 12 and Refs. therein].
Infrared spectra of K 2 Be(IO 3 ) 4 ·2H 2 O and
(NH4)2Be(IO3)4·2H2O are shown in Fig. 3 in the regions
of 1700-400 cm-1. The shapes of the spectra as well as
the wavenumbers of the respective infrared bands are
similar for both compounds, thus confirming the X-ray
powder diffraction data that K2Be(IO 3) 4·2H2O and
(NH4)2Be(IO3)4·2H2O are isostructural. Symmetrical
sharp bands at around 870 cm-1 and 680 cm-1 appear in
the spectra of the double salts, which might be attributed
to the translatory modes of the beryllium tetrahedra (the
bands at 867 cm-1 are assigned to ν32 and those at
lower frequencies - 683 and 680 cm-1 to ν12 for the
potassium and ammonium compounds, respectively).
The comparatively high intensity of these bands is owing
to the strong Be-O interactions, i.e. to the covalent character of these bonds. The shape of the bands allows us
to assume that the beryllium tetrahedra are comparatively regular with respect to the Be-O bond lengths, i.e.
a local molecular symmetry of the BeO4 tetrahedra is to
Td. Indeed, the preview of the crystal structures of some
beryllium iodates [13-15] as well as of some beryllium
sulfates and selenates [16-19] shows that the BeO4 tet-
rahedra exhibit close values of the Be-O bond lengths,
irrespective of the site symmetry of the beryllium tetrahedra and the type of the coordination environment of the
Be2+ ions. Then, the bands in the regions of 830-700 cm-1
are assigned to the stretching modes of the iodate ions.
The bands of lower intensities at 824 and 806 cm-1 are
attributed to ν1 and those in the regions of 790-700 cm-1
to ν3, i.e. the energetic order of the stretching modes is
ν1 > ν3 as it was commented above in the text. The
appearance of ν1 for the iodate ions shows that the molecular symmetry of IO3- deviates from C3v (two site symmetries - C1 and Cs are possible). The two bands for ν1
separated from each other by 18 cm-1 (this difference is
too large for crystal field splitting effects) allows us to
assume that probably at least two crystallographically
different iodate ions exist in the structures of both compounds. The bands at 470 and 465 cm-1 are attributed
to the bending modes ν4 of the iodate ions in the potassium and ammonium compounds, respectively. The
bands at 988 and 956 cm-1 (potassium compound) and
that at 964 cm-1 (ammonium compound) are assigned
to water librations (see text below). The strong band
centered at 1426 cm-1 and two shoulders at 1415 and
1455 cm-1 are attributed to asymmetric bending modes
ν4 of the NH4+ ions. The bands at 3050 cm-1 and partly
that at 3177 cm-1 are assigned to the stretching modes
of the ammonium ions.
Raman spectra of K 2 Be(IO 3 ) 4 ·2H 2 O and
(NH4)2Be(IO3)4·2H2O are presented in Fig. 4. The bands
in the region of 820–740 cm-1 correspond to the stretching modes of the iodate ions. The bands at the higher
306
V. Karadjova, M. Georgiev, D. Stoilova
Fig. 4. Raman spectra of K2Be(IO3)4·2H2O and (NH4)2Be
(IO3)4·2H2O.
frequency (876 cm-1) are assigned to Be–O vibrations.
The Raman bands in the spectral region of 470-300
cm-1 correspond probably only to the bending modes of
the IO3- ions (ν4 and ν2; the bands at the higher frequencies are assigned to ν2), since the Raman bands of the
bending modes corresponding to the BeO4 tetrahedra
are reported to appear as very weak bands [3, 10, 11].
The large widths of the spectral regions in which the
bending modes of the iodate ions are observed indicate
that these ions are strongly distorted with respect to the
O-I-O bond angles. The Raman bands at frequencies
lower than 300 cm-1 are due to lattice modes.
The small beryllium ions are reported to display
strong Be-OH2 interactions (synergetic effect), i.e. a
strong increase of the hydrogen bond strength of water
molecules coordinated to beryllium ions due to the large
ionic potential of Be2+. This is revealed by the strong
and very strong hydrogen bonds formed in hydrated
beryllium salts (short O w···O bond distances and
considerable red-shifts of the OD stretches of matrixisolated HDO molecules), even if the hydrogen bond
acceptor strengths of the corresponding oxygen acceptors are small [3, 20-22].
In Fig. 5 are shown infrared spectra of both compounds in the region of the OH vibrations of the water
molecules and the stretching modes of the ammonium
ions (left); νOD of uncoupled OD vibrations of matrixisolated HDO molecules (samples containing about 15 %
D2O, middle) and spectra in the low frequency region
of about 90 % deuterated samples (right). The low frequencies of the bands corresponding to OH and OD
vibrations in the spectrum of K2Be(IO3)4·2H2O (2964
cm-1 for νOH of H2O and 2238 cm-1 for νOD of HDO)
indicate that comparatively strong hydrogen bonds are
formed in this compound. The isotopic ratio νOH/νOD
has value of 1.32. The ν OH modes of H 2 O in
(NH4)2Be(IO3)4·2H2O could not be recognized precisely,
since these modes are mixed with the stretching modes
of the ammonium ions. We made an attempt to calculate the band position of νOH in the ammonium salt (νOD
appears at 2373 cm-1) using isotopic ratios in the range
of 1.30-1.34, which is characteristic for crystal hydrates
[20]. If we use an isotopic ratio 1.34 a band at 3180
cm-1 must appear in the spectrum, which is very close
to the band observed at 3177 cm-1. So, we believe that
the band at 3177 cm-1 contributes vibrations of water
molecules and ammonium ions. When the wavenumbers
of n OD in the spectra of K 2 Be(IO 3 ) 4 ·2H 2 O and
(NH4)2Be(IO3)4·2H2O are compared, it is seen that the
hydrogen bonds formed in the potassium compound are
remarkably stronger than those formed in the ammonium one (∆ν has value of 135 cm-1). This spectroscopic
finding might be explained with considerably different
proton acceptor capability of the iodate ions in both
compounds. The IO3- ions in (NH4)2Be(IO3)4·2H2O are
involved in hydrogen bonds with ammonium anions
additionally to those with water molecules. As a result
the proton acceptor ability of the IO3- ions in the ammonium compound decreases as compared to that of
the same ions in the respective potassium one, thus leading to the formation of weaker hydrogen bonds in
(NH4)2Be(IO3)4·2H2O (anti-cooperative or proton acceptor competitive affect [21]). The band corresponding to
ν2 of heavy water (about 90 % deuterated samples, see
Fig. 5 (right)) is detected at 1193 cm-1 in the spectrum of
the potassium compound (the respective band corresponding to the ammonium compound could not be recognized well, since the bending modes of ND4+ appear in
307
Journal of the University of Chemical Technology and Metallurgy, 47, 3, 2012
1193
668
470
Transmittance (%)
877
2965
2238
869
833
715
731
824
800
778
K Be(I O!) "
2H O
755
774
868
3050
713
825
2373
3177
465
659
1079
803
753
(NH ") Be(I O!)"
2H O
3200
2800
2400
2200
774
1200
800
-1
Wavenumber (cm )
400
Fig. 5. Infrared spectra of K2Be(IO3)4·2H2O and (NH4)2Be(IO3)4·2H2O in the regions of: ν3 and ν1 of IO3- ions, ν3’ and ν1’of
BeO4 tetrahedra, librations of D2O (90% deuterated samples; right); stretches of OH (left); uncoupled OD vibrations of
matrix-isolated HDO molecules (ca. 15% D2O, middle).
this region). It is worthy to notice that only one band
corresponding to νOD of the HDO molecules and one
band corresponding to heavy water is observed in the
spectrum of the potassium compound. Consequently, two
conclusions could be drawn: (i) one crystallographically
type of water molecules exist probably in the structures
in the compounds under study and (ii) the molecular
symmetry of the water molecules is close to C2v (at least
at ambient temperature).
The water librations (rocking, wagging and twisting) appear in the region below 1000 cm-1 and consequently a strong overlapping of these modes with modes
of other entities is expected. It is reported in [3] that
due to a coupling of water librations with translatory
modes of BeO4 tetrahedra and internal modes of the
IO 3 - ions the isotopic ratios (ν R(H 2O)/νR(D 2O)) in
Be(IO3)2·4H2O have values close to 1. This phenomenon was observed also in the case of other beryllium
Table 3. X-ray powder diffraction data of K 2Be(IO 3)4·2H2O and
(NH4)2Be(IO3)4·2H2O.
K2Be(IO3)4·2H2O
308
(NH4)2Be(IO3)4·2H2O
d obs/Å
I/I0 d obs/Å
I/I0 d obs/Å
I/I0
d obs/Å
I/I0
6.740
5.589
4.691
4.128
3.510
3.457
3.368
3.284
2.8942
2.8501
2.7352
2.4326
2.3470
<5
36
16
22
<5
<5
100
68
25
16
12
5
<5
8
25
6
<5
<5
11
11
<5
<5
<5
7
12
<5
25
67
45
10
<5
100
57
32
8
18
2.4635
2.3755
2.1200
2.0564
2.0311
1.9855
1.9482
1.8208
1.7874
1.7454
1.7086
1.6119
9
<5
15
21
14
11
<5
<5
18
11
6
<5
2.0865
2.0312
2.0081
1.9547
1.9211
1.7612
1.7266
1.6840
1.6427
1.5925
7.107
6.830
6.172
5.653
4.738
4.195
3.555
3.499
3.418
3.321
2.9333
2.8832
2.7726
V. Karadjova, M. Georgiev, D. Stoilova
compounds – sulfates and selenates [16-19]. When Figs.
3 and 5 are compared (protonated and about 90% deuterated samples, respectively) it is seen that the bands
of low intensities - 988 and 956 cm-1 in the spectrum of
the potassium compound and that at 964 cm-1 in the
spectrum of the ammonium one (protonated samples)
disappear in the spectra of the deuterated ones. New
bands at 877 and 833 cm-1 are detected in the spectrum
of the highly deuterated potassium compound.
Consequently, these bands could be attributed to water
librations. The bands at 988 and 956 cm-1 are assigned
to rocking and wagging librations of H2O in the potassium salt, respectively. The corresponding isotopic ratios νRW(H2O)/νRW(D2O) have values of 1.13 and 1.15
for both librations (rocking and wagging). In the case of
the ammonium compound the bands corresponding to
the rocking and wagging modes of H2O coincide (band
at 964 cm-1). The respective bands corresponding to librations of D2O in the spectrum of the highly deuterated
sample appear probably in the region where vibrations
of the BeO4 tetrahedra occur and could not be recognized. The twisting modes of H2O are not expected to
appear in the infrared spectra owing to the local molecular symmetry of the water molecules (close to C2v) [20].
CONCLUSIONS
The solubility in the tree-component MeIO3Be(IO3)2-H2O (Me = K, NH4+) systems at 25°C is studied. It has been established that double salts,
K2Be(IO3)4·2H2O and (NH4)2Be(IO3)4·2H2O, crystallize
in the above systems, which are isostructural as deduced
from X-ray powder diffraction and vibrational
spectroscopy data. The infrared and Raman spectra
reveal: (i) The infrared spectroscopic experiments allow us to assume that probably at least two crystallographically different iodate ions exist in the structures,
which are strongly distorted. (ii) The water molecules
in the potassim compound form comparatively strong
hydrogen bonds owing to the strong Be-OH2 interactions (synergetic effect). (iii) The hydrogen bonds formed
by the water molecules in the ammonium compound
(bonds of moderate strength) are weaker as compared
to those formed in the potassium one due to the anticooperative effect (the IO3- ions are involved in hydrogen bonds with NH4+ ions additionally to those with
water molecules and as a result the proton acceptor
strength of the iodate ions decreases). (iv) Due to a strong
coupling of water librations with both the translatory
modes of BeO4 tetrahedra and the internal modes of the
IO3- ions the isotopic ratios (νR(H2O)/νR(D2O)) have
values close to 1. (v) The infrared spectroscopic experiments reveal that one crystallographically type of water
molecules exists in the structures of the double salts
with a local molecular symmetry close to C2v. (vi) The
analysis of the infrared spectra allows us to assume that
the Be2+ ions are coordinated with two water molecules
and two crystallographically different iodate groups, thus
forming [Be(H2O)2(IO3)2] tetrahedra. However, our claim
needs an additional structural analysis.
REFERENCES
1. M. Maneva, M. Georgiev, Thermal and calorimetric
investigation on crystalline hydrates of beryllium
iodates, Thermochim. Acta, ' , 1985, 627-631.
2. M. Maneva, M. Georgiev, IR spectra of
Be(IO3)2·nH2O (n = 4, 0) and of the deuterated analogue, Spectrosc. Lett., !, 1990, 831-844.
3. H.D. Luzt, N. Lange, M. Maneva, M. Georgiev,
Be(IO3)2·4H 2O, ein Hydrat mit Ungewöhnlicher
Bindungsstruktur und Gitterdynamik, Z. Anorg. Allg.
Chem., #'", 1991, 77-86.
4. M. Maneva, M. Georgiev, H.D. Luzt, N. Lange, Zur
Kenntnis von Berilliumiodat-Periodat – Roentgenographische, IR- und Raman-spektroskopische
Untersuchungen, Z. Naturforsch., "$>, 1991, 795-799.
5. D.L. Zagorski, E.V. Bryukhova, M.P. Georgiev, 127I
Nuclear Quadropole Resonance Spectra of Beryllium Iodates, Russian J. Phys. Chem., $&, 1994,
2054-2055.
6. M. Georgiev, M. Maneva, Synthesis and Thermal
Behaviour of (NH4)2Be(IO3)4·2H2O, Polyhedron,
$, 1997, 441-445.
7. Ì. Georgiev, Synthesis and thermal behavior of
K2Be(IO3)4·2H2O, J. Univ. Chem. Technol. Met.
(Sofia), !!, 1998, 105-113.
8. M. Nadoliisky, M. Georgiev, D. Nikolova, V.
Karadjova, Dielectric properties of Be(IO3)2·4H2O
crystals, J. Mater. Sci.,$, 2005, 667-678.
9. K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds, John Wiley
& Sons, New York, 1986.
10. F. Bertin, J. Deronault, Etude structurale des chlorure
309
Journal of the University of Chemical Technology and Metallurgy, 47, 3, 2012
et sulfate de béryllium hydratés par spectrométrie
infrarouge et Raman, Can. J. Chem., #%, 1979, 913-919.
11. C. Pigenet, Activités Raman et Infrarouge des Cristaux
Pieziélectriques BeSO 4·4H 2O et BeSO 4·4D 2O –
Activité Raman des Modes Polaires, J. Raman
Spectrosc., !, 1982, 262-269.
12. G. Pracht, R. Nagel, E. Suchanek, N. Lange, H.D.
Lutz, IR- und Raman-Spectren der isotypen
Iodathydrate M(IO3)2·4H2O (M = Mg, Ni, Co);
Kristallstruktur von Co(IO3)2·4H2O, Z. Anorg. Allg.
Chem., $ ", 1998, 1355-1362.
13. H.D. Lutz, H. Möller, M. Maneva, W. Paulus, A.
Cousson, J. Lauriat, E. Elkaim, Z. Kristallogr., ,
1996, 170-175.
14. J. Macicek, M. Maneva, M. Georgiev, Structure of
Be(IO3)2·2HIO3·6H2O, Z. Kristallogr., '', 1992,
177-184.
15. Z. Zhang, H.D. Lutz, M. Georgiev, M. Maneva, The
First Beryllium Periodate: Be(H4IO6)2·4H2O, Acta
Crystallogr., +# , 1996, 2660-2662.
16. M. Wildner, D. Stoilova, M. Georgiev, V. Karadjova,
J. Mol. Struct., Beryllium selenate tetrahydrate,
BeSeO4·4H2O: crystal structure and infrared spectroscopy %%, 2004, 123-130.
17. M. Georgiev, D. Stoilova, M. Wildner, V. Karadjova,
310
J. Mol. Struct., Potassium beryllium selenate dihydrate, K2Be(SeO4)2·2H2O: Preparation, structure and
infrared spectroscopy, %# , 2005, 158-165.
18. M. Georgiev, M. Wildner, D. Stoilova, V. Karadjova,
J. Mol. Struct., Potassium beryllium sulfate
dihydrate, K2Be(SO4)2·2H2O: Crystal structure and
infrared spectroscopy, %#!, 2005, 104-112.
19. M. Georgiev, M. Wildner, D. Stoilova, V. Karadjova,
Vibr. Spectrosc., Preparation, crystal structure and
infrared spectroscopy of the new compound rubidium
beryllium sulfate dihydrate, Rb2Be(SO4)2·2H2O, "",
2007, 266-272.
20. H.D. Lutz, Bonding and Structure of Water Molecules in Solid Hydrates. Correlation of Spectroscopic and Structural Data, Struct. Bond. (Berlin),
$', 1988, 97-123.
21. H.D. Lutz, Structure and strength of hydrogen bonds
in inorganic salts, J. Mol. Struct., $"$, 2003, 227236.
22. H.D. Lutz, E. Suchanek, Intramolecular coupling
of BrO stretching vibrations in solid bromates,
infrared and Raman spectroscopic studies on
M(BrO 3 ) 2 ·6H 2 O (M = Mg, Co, Ni, Zn) and
Ni(ClO3)2·6H2O, Spectrochim. Acta, #$), 2000,
2707-2713.