Hexaaqua Cation Research Articles

Comparative analysis of exchangeable aluminum in a tropical soil under long-term no-till cultivation

Aluminum toxicity is a key determinant of crop yield for acid soils. Techniques used to characterize a soil’s exchangeable Al content often yield discordant results, thus impeding the implementation of corrective measures. We critically compared three such techniques – back-titration, ICP-AES, and 27Al NMR – for a tropical Oxisol under long-term (8-years) no-till cultivation involving four different cropping-systems and three pH control regimens. ICP-AES was superior in terms of accuracy, level of quantification (LOQ), practicable pH range, speed, cost, and versatility. By comparison, back-titration consistently overestimated exchangeable Al, whereas 27Al-NMR, though accurate, had a higher LOQ and is inherently non-quantitative between pH 5.4 and 6.3 owing to extreme quadrupolar broadening of Al(OH)n(H2O)6−n(3̶−n)+ (n = 1–3) signals. The only Al species detected by NMR in any of the soil extracts was the toxic Al hexaaqua cation, Al(H2O)63+, despite an appreciable presence of dissolved organic matter. Application of either dolomitic lime or calcium-magnesium silicate (CMS) as a pH corrective significantly decreased exchangeable Al in the upper soil layers. None of the decrease, however, was attributable to insoluble aluminosilicates having formed as a consequence of CMS dissolution. Rotation crops of wheat (T. aestivum) and showy rattlebox (C. spectabilis) depleted exchangeable Al in the upper soil layers, whereas palisade grass (Brachiaria brizantha) had no discernable effect on Al availability. Plots which incorporated any one of the three rotation crops provided equally high yields of soybean in year-8 when pH (1 M KCl) exceeded 4.9 ± 0.2 and Al saturation was less than 25 ± 5% (AlICP ≤ 22 ± 21 mg kg−1), on average, in the 0–20 cm soil horizon.

The influence of the metal cations and microhydration on the reaction trajectory of the N3 ↔ O2 thymine proton transfer: Quantum mechanical study.

This study involves the intramolecular proton transfer (PT) process on a thymine nucleobase between N3 and O2 atoms. We explore a mechanism for the PT assisted by hexacoordinated divalent metals cations, namely Mg2+ , Zn2+ , and Hg2+ . Our results point out that this reaction corresponds to a two-stage process. The first involves the PT from one of the aqua ligands toward O2. The implications of this stage are the formation of a hydroxo anion bound to the metal center and a positively charged thymine. To proceed to the second stage, a structural change is needed to allow the negatively charged hydroxo ligand to abstract the N3 proton, which represents the final product of the PT reaction. In the presence of the selected hexaaqua cations, the activation barrier is at most 8 kcal/mol. © 2017 Wiley Periodicals, Inc.

GETERONUCLEAR BIS(GALACTARATO)GERMINATES OF COBALT(ІІ), COPPER(ІІ), NICKEL(ІІ): SYNTHESIS, STRUCTURE AND CHEMICOPHYSICAL PROPERTIES

Heterometallic bic(galactarato)germanates of cobalt(ІІ), copper(ІІ) and nickel(ІІ) were synthesized for the first time and characterized with the method of elemental analyses, thermogravimetry and IR-spectroscopy.The IR-spectrum of the synthesized compounds showed the presence of nas(COO-) ~ 1600 сm-1, ns(COO-) ~ 1390 сm-1 and valence vibrations of the bond M-O ~ 530 сm-1. All this points on the deprotonation of carboxylic groups. The values of valence vibrations of carboxylate ions, the absence of narrow band ν(ОН) at 3600 сm-1 and presence of ν(Ge-O) at685 сm-1 allows us to conclude, that germanium coordination unit is formed by the bonding with oxygen atoms in hydroxyl groups and without any participation of ones in carboxylic groups. This statement is confirmed by the absence of hydroxyl ν(C-O) vibrations, which are specific for galactaric acid, and presence of alkoxyl n(С-О) vibrations. It was found that inner sphere of the synthesized compounds performs to be different-metal Ge4+–M2+ complex anion, the charge of which is neutralized by the hexa-aqua cation of 3d-meteal [М(Н2О)6][Ge(μ-HGala)2{М(H2O)2}2]·5H2O (HGala5- – galactaric acid anion, М – Сo2+, Ni2+, Cu2+). Their structure and chemical reaction is suggested to be next: GeCl4 + 2H6Gala + 3M(CH3COO)2 + 10NH4OH + 5H2O → [M(H2O)6][Ge(μ3-HGala)2{M(H2O)2}2]·5H2O + 6CH3COONH4 ++4NH4Cl

Crystal structures of hydrates of simple inorganic salts. I. Water-rich magnesium halide hydrates MgCl2·8H2O, MgCl2·12H2O, MgBr2·6H2O, MgBr2·9H2O, MgI2·8H2O and MgI2·9H2O

The previously reported structures of the hydrates of simple inorganic salts that crystallize at room temperature are generally well determined. This is not true for water-rich hydrates, which crystallize at temperatures below 273 K. In this series, investigations of the crystal structures of water-rich hydrates crystallized from aqueous solutions at low temperatures are presented. Reported herein are the structures of a set of magnesium salts. Crystals of MgCl2·8H2O (magnesium dichloride octahydrate), MgCl2·12H2O (magnesium dichloride dodecahydrate), MgBr2·6H2O (magnesium dibromide hexahydrate), MgBr2·9H2O (magnesium dibromide nonahydrate), MgI2·8H2O (magnesium diiodide octahydrate) and MgI2·9H2O (magnesium diiodide nonahydrate) were grown from their aqueous solutions at temperatures below 298 K according to the solid-liquid phase diagrams. All structures are built up from Mg(H2O)6 octahedra. Dimensions and angles in the hexaaqua cation complexes are very similar and variation is not systematic. The anions are incorporated into a specific network of O-H...X hydrogen bonds.

X-Ray diffraction study of M(Aet)2·11H2O (M = Mn, Mg, and Mn0.5Mg0.5) and the crystal structure of [Mn(OH2)6](Aet)2·5H2O

X-ray phase and X-ray spectral analyses are performed for newly synthesized M(Aet)2·11H2O compounds, where M(II) = Mn, Mg, and Mg0.5Mn0.5, (Aet)− = (C10H11N4O2S2)−, the anion of ethazol (2-(paraaminobenzene sulfanilamide)-5-ethyl-1,3,4-thiadiazole). It is found that these compounds are isostructural. In the third compound, Mg and Mn statistically substitute for each other and the substitution takes place at any ratio of these metals. The structure of crystals of the [Mn(OH2)6](Aet)2·5H2O compound is studied: a = 17.160(2) A, b = 14.115(1) A, c = 15.130(2) A, β = 98.23(3)°, P21/n, Z = 4, R(F) = 0.045. The compound consists of complex [Mn(OH2)6]2+ hexaaqua cations, (Aet)− anions, and five water molecules.

Breakdown kinetics of the tri-chromium(III) oxo acetate cluster ([Cr 3O(OAc) 6] +) with some ligands of biological interest

Kinetics for the breakdown of the trinuclear chromium acetate cluster, [Cr 3O(OAc) 6] +, with a series of monoprotic and diprotic ligands in weakly acidic aqueous media (pH ∼ 4 or ∼5) have been investigated spectrophotometrically at 40–60 °C. The results point to an ion-pair equilibrium as the first step followed by associative interchange mechanism forming the mononuclear product of the reaction. Pseudo-first-order rates were determined from absorbance data and associated activation parameters were calculated using the Eyring equation. Enthalpy and entropy terms of the reactions (e.g., histidine, Δ H ‡ = 75 ± 15 kJ mol −1, Δ S ‡ = −130 ± 25 J K −1 mol −1; lactic acid, Δ H ‡ = 66 ± 13 kJ mol −1, Δ S ‡ = −155 ± 30 J K −1 mol −1; glycine, Δ H ‡ = 31 ± 6 kJ mol −1, Δ S ‡ = −225 ± 45 J K −1 mol −1) are consistent with an associative interchange ( I a) mechanism, and produce a linear isokinetic plot (slope = 50 °C). Rates and activation parameters are comparable to those of substitution reactions of the chromium(III) hexaaqua cation. Other ligands studied included malonic acid and the amino acid, aspartic acid. Observed rates are faster than water exchange rates, but typically slower than anion substitution rates, and indicate that trinuclear chromium(III) clusters are expected to be kinetically stable in neutral to slightly acidic conditions.

Catena-Poly[hexaaquazinc(II) [bis[dichlorozincate(II)]-μ-pyridine-4-carboxylato-κ2N,O] dihydrate

In the title compound, {[ZnCl2(C6H4NO2)]2[Zn(H2O)6]·2H2O}n, one Zn atom is involved in the formation of one-dimensional infinite zigzag anionic chains, whereas the second Zn atom, located on a twofold axis, is surrounded by six water mol­ecules as a hexaaqua cation. The occurrence of O—H⋯O and O—H⋯Cl hydrogen bonds results in a supra­molecular three-dimensional network.

Spectroscopic, Magnetochemical, and Crystallographic Study of Cesium Iron Phosphate Hexahydrate: Characterization of the Electronic Structure of the Iron(II) Hexa-aqua Cation in a Quasicubic Environment

Spectroscopic, magnetochemical, and crystallographic data are presented for CsFe(H2O)6PO4, a member of a little-known isomorphous series of salts that facilitates the study of hexa-aqua ions in a quasicubic environment. Above 120 K, the deviations from cubic symmetry are minimal, as shown by the first example of an iron(II) Mössbauer spectrum that exhibits no measurable quadrupole splitting. Two crystallographically distinct [Fe(OH2)6]2+ complexes are identified from inelastic neutron-scattering (INS) experiments conducted between 2 and 15 K. The data are modeled with the ligand-field Hamiltonian, H = lambdaLŝ + betaB(kL + 2ŝ) + Delta(tet){Lz2 - (1/3)L(L + 1)} + Delta(rhom){Lx2 - Ly2}, operating in the ground-term (5)T(2g) (Oh) basis. An excellent reproduction of INS, Mössbauer, HF-EPR, and magnetochemical data are obtained in the 2 and 15 K temperature regimes with the following parameters: lambda = -80 cm(-1); k = 0.8; site A Delta(tet) = 183 cm(-1), Delta(rhom)= 19 cm(-1); site B Delta(tet) = 181 cm(-1), Delta(rhom)= 12 cm(-1). The corresponding zero-field-splitting (ZFS) parameters of the conventional S = 2 spin Hamiltonian are as follows: site A D = 12.02 cm(-)(1), E = 2.123 cm(-1); site B D = 12.15 cm(-1), E = 1.37 cm(-1). A theoretical analysis of the variation of the energies of the low-lying states with respect to displacements along selected normal coordinates of the [Fe(OH2)6]2+, shows the zero-field splitting to be extremely sensitive to small structural perturbations of the complex. The expressions derived are discussed in the context of spin-Hamiltonian parameters reported for the [Fe(OH2)6]2+ cation in different crystalline environments.

Electronic Raman spectroscopy of the vanadium(III) hexaaqua cation in guanidinium vanadium sulphate: Quintessential manifestation of the dynamical Jahn–Teller effect

Single-crystal Raman spectra are presented for the salt [C(NH2)3][V(OH2)6](SO4)2, displaying electronic transitions between the trigonal components of the vanadium(III) 3T1g(Oh) ground term. The 3A-->3E(C3) electronic Raman band is centered at approximately 2720 cm-1, and exhibits extensive structure, revealing the energies of the spinor components of the 3E(C3) term for the two crystallographically distinct [V(OH2)6]3+ cations. The data are interpreted in conjunction with parameters previously reported from an electron paramagnetic resonance study of the salt. A satisfactory reproduction of the electronic Raman profile and ground-state spin-Hamiltonian parameters is achieved by employing a (3A plus sign in circle3E)multiply sign in circle e vibronic coupling model, in which the spin-orbit splitting of the 3E(C3) is quenched significantly by the Ham effect, and the intensity of harmonics of the Jahn-Teller active vibration enhanced by their proximity to the electronic Raman bands. The model gives an excellent account of the intensities of the electronic Raman bands, which are shown to depend profoundly on both temperature and the selected component of the polarizability tensor. The electronic Raman profile changes notably upon deuteriation, a result that exposes deficiencies in the single-mode coupling model.

Structure and Bonding of the Vanadium(III) Hexa-Aqua Cation. 1. Experimental Characterization and Ligand-Field Analysis

Spectroscopic and crystallographic data are presented for salts containing the [V(OH(2))(6)](3+) cation, providing a rigorous test of the ability of the angular overlap model (AOM) to inter-relate the electronic and molecular structure of integer-spin complexes. High-field multifrequency EPR provides a very precise definition of the ground-state spin-Hamiltonian parameters, while single-crystal absorption measurements enable the energies of excited ligand-field states to be identified. The EPR study of vanadium(III) as an impurity in guanidinium gallium sulfate is particularly instructive, with fine-structure observed attributable to crystallographically distinct [V(OH(2))(6)](3+) cations, hyperfine coupling, and ferroelectric domains. The electronic structure of the complex depends strongly on the mode of coordination of the water molecules to the vanadium(III) cation, as revealed by single-crystal neutron and X-ray diffraction measurements, and is also sensitive to the isotopic abundance. It is shown that the AOM gives a very good account of the change in the electronic structure, as a function of geometric coordinates of the [V(OH(2))(6)](3+) cation. However, the ligand-field analysis is inconsistent with the profiles of electronic transitions between ligand-field terms.

Structure and Bonding of the Vanadium(III) Hexa-Aqua Cation. 2. Manifestation of Dynamical Jahn−Teller Coupling in Axially Distorted Vanadium(III) Complexes

Ground-state spin-Hamiltonian parameters, magnetic data, and electronic Raman spectra of hexacoordinate vanadium(III) complexes are calculated with consideration to the ((3)A (3)E) e vibronic interaction and compared to experimental data. It is shown that the zero-field-splitting of the (3)A(g) (S(6)) ground term may be reduced significantly by the dynamical Jahn-Teller effect, particularly when the pi-anisotropy of the metal-ligand bonding interaction is significant, and the energy of the Jahn-Teller active vibration is comparable to the diagonal axial field. The dynamical Jahn-Teller effect may also give rise to a significant enhancement in the Raman intensity of overtones and higher harmonics of Jahn-Teller active vibrations, when the energies of these transitions fall in the proximity of intra-(3)T(1g) (O(h)) electronic Raman transitions. A simple method of conducting vibronic coupling calculations is described, employing ligand field matrices generated by angular overlap model calculations, which may in principle be applied to any transition metal complex.

Synthesis and Crystal Structure of Two Modifications of Hexaaquamagnesium(II) Hypophosphite

Two modifications of hexaaquamagnesium(II) hypophosphite [Mg(H2O)6](H2PO2)2 have been synthesized and structurally characterized. Literature data are available for one of these forms. The geometrical characteristics of hexaaqua cations, hypophosphite anions, and nets of hydrogen bonds between the hypophosphite anions and the coordinated water molecules are analyzed. The packing motif of the structure-forming fragments was found to be the same for the two structures, except that modification of the inner structure of the complex cation leads to different nets of hydrogen-bonded cations and anions.

Aqua Ions. 2. Structural manifestations of the Jahn-Teller effect in the beta-alums.

Variable-temperature single-crystal neutron diffraction structures of the alums CsM(III)(SO(4))(2).12D(2)O, where M(III) = Ti, V, Mn, and Ga, are reported. Structural differences are highlighted by the titanium and manganese alums, which undergo cubic (Pathremacr;) to orthorhombic (Pbca) phase transitions at approximately 13 and approximately 156 K, respectively. The structural instability exhibited by these salts is interpreted as arising from cooperative Jahn-Teller interactions, and these measurements characterize the structural changes that result from the coupling between the electronic and vibrational states. Although the symmetry changes associated with the phase transformations are analogous for the Ti and Mn alums, the low-temperature geometries of the tervalent hexaaqua cations are markedly different. Whereas the MnO(6) framework is subject to a pronounced tetragonal elongation, changes in the Ti-O bond lengths are very modest; but significant changes in the O-Ti-O bond angles and in the disposition of the coordinated water molecules are identified. The large differences in the transition temperatures and in the low-temperature stereochemistries of the [Ti(OD(2))(6)](3+) and [Mn(OD(2))(6)](3+) cations are related to the sensitivity of the energies of the t(2g) (O(h)) and e(g) (O(h)) orbitals to the various asymmetric vibrations of the hexaaqua complex.

Influence of Jahn-Teller coupling on the magnetic properties of transition metal complexes with orbital triplet ground terms: magnetization and electronic Raman studies of the titanium(III) hexa-aqua cation.

Magnetization and electronic Raman data are presented for salts of the type Cs[Ga:Ti](SO(4))(2) x 12H(2)O, which enable a very precise definition of the electronic structure of the [Ti(OH(2))(6)](3+) cation. The magnetization data exhibit a spectacular deviation from Brillouin behavior, with the magnetic moment highly dependent on the strength of the applied field at a given ratio of B/T. This arises from unprecedented higher-order contributions to the magnetization, and these measurements afford the determination of the ground-state Zeeman coefficients to third-order. The anomalous magnetic behavior is a manifestation of Jahn-Teller coupling, giving rise to low-lying vibronic states, which mix into the ground state through the magnetic field. Electronic Raman measurements of the 1%-titanium(III)-doped sample identify the first vibronic excitation at approximately 18 cm(-1), which betokens a substantial quenching of spin-orbit coupling by the vibronic interaction. The ground-state Zeeman coefficients are strongly dependent on the concentration of titanium(III) in the crystals, and this can be modeled as a function of one parameter, representing the degree of strain induced by the cooperative Jahn-Teller effect. This study clearly demonstrates the importance that the Jahn-Teller effect can have in governing the magnetic properties of transition metal complexes with orbital triplet ground terms.

Electronic Raman transitions from the vanadium(III) hexa-aqua cation, in guanidinium vanadium sulphate

Electronic Raman transitions ( 3 A→ 3 E( C 3) ) have been observed between the trigonally split components of the 3 T 1 g ( O h ) ground term of the vanadium(III) hexa-aqua cation in guanidinium vanadium sulphate hexa-hydrate. The magnitude of the trigonal field splitting is considerable, ∼2720 cm −1, which is consistent with expectations based on the stereochemistry of the [V(OH 2) 6] 3+ complex. It is shown that a satisfactory reproduction of the electronic Raman band profile can be obtained only by assuming a ( 3 A⊕ 3 E)⊗e vibronic coupling model.

Raman Spectroscopic Measurements of Scandium(III) Hydration in Aqueous Perchlorate Solution and ab Initio Molecular Orbital Studies of Scandium(III) Water Clusters: Does Sc(III) Occur as a Hexaaqua Complex?

We have shown that Sc(III) in aqueous perchlorate solution occurs as a hexaaqua cation. The weak, polarized Raman band assigned to the ν1(a1g)(ScO6) mode of the hexaaqua Sc(III) ion has been studied as a function of concentration. Besides the isotropic component at 442 cm-1, two weak depolarized modes at 295 and 410 cm-1 were measured in the Raman effect. These two modes of the ScO6 unit were assigned to ν5(f2g) and ν2(eg), respectively. The infrared active mode,ν3(f1u), was found at 460 cm-1. The Raman spectroscopic data suggest that the hexaaqua Sc(III) ion is stable in perchlorate solution within the concentration range measured. Furthermore, the frequency data confirm the centrosymmetry of the Sc(III) aqua complex, contrary to earlier Raman results. The ScO6 unit possesses Oh symmetry (water seen as point mass). These findings are in contrast to ScCl3 solutions, where chloride replaces water in the first hydration sphere and forms one or more chloro complexes. Gas-phase structures, binding energies, and enthalpies are reported for small [Sc(OH2)n]3+ clusters, with one to nine water molecules in the first sphere. Ab initio molecular orbital calculations were performed at the HF and MP2 levels of theory using different basis sets up to 6-31+G*. The water molecules in these clusters coordinate the Sc3+ in highly symmetric arrangements that tend to enhance electrostatic charge−dipole interactions while minimizing ligand−ligand repulsion. The Sc−O bond length for the [Sc(OH2)6]3+ cluster reproduces the experimentally determined bond length (EXAFS) of 2.18 Å. The theoretical binding energy for the [Sc(OH2)6]3+ ion was calculated and accounts for ca. 54−59% of the experimental single ion hydration enthalpy of Sc(III). The stability of the hexaaquascandium(III) cluster could be demonstrated by comparing the stability of the [Sc(OH2)6(OH2)]3+ cluster with the [Sc(OH2)7]3+ cluster, resulting in the stability of the former. The frequencies of ν1(ScO6) of the [Sc(OH2)6]3+ cluster are ca. 11% lower than the experimental frequency. The reason for this discrepancy was discussed and found to lie in the lack of the second hydration sphere which was subsequently modeled as the [Sc(OH2)18]3+ cluster, denoted Sc[6+12]. Frequencies of the ScO6 unit for the Sc[6+12] cluster were calculated and agree with the experimental values. The binding enthalpy resembles that of the single ion hydration enthalpy.

Raman Spectroscopic Studies of Scandium(III) Hydration in Aqueous Solution - about the First Hydration Sphere of Sc(III) in Solution

It has been shown conclusively that Sc(III) in aqueous perchlorate solution occurs as an hexaaqua cation. The weak, polarized Raman band assigned to theBesides the polarized component at 442 cmThese findings are also in contrast to the results found in Sc

Aqueous Solution Chemistry of Scandium(III) Studied by Raman Spectroscopy and ab initio Molecular Orbital Calculations

Aqueous solutions of Sc(ClO4)3,ScCl3, and Sc2(SO4)3 were studied by Ramanspectroscopy over a wide concentration range. In aqueous perchlorate solutionSc(III) occurs as an hexaaqua cation. The weak, polarized Raman band assignedto the ν1(a1g) ScO6 mode of the hexaaqua-Sc (III) ion has been studied as afunction of concentration and temperature. The ν1(a1g) ScO6 mode at 442 cm−1of the hexaaqua—Sc(III) shifts only 3 cm−1 to lower frequency and broadensabout 20 cm−1 for a 60°C temperature increase. The Raman spectroscopic datasuggest that the hexaaqua-Sc (III) ion is stable in perchlorate solution within theconcentration and temperature range measured. Besides the polarized componentat 442 cm−1, two weak depolarized modes at 295 and 410 cm−1 were measuredin the Raman effect. These two modes of the ScO6 unit were assigned to ν3(f2g)and ν2(eγ), respectively. The infrared active mode ν3(f1u) was measured at 460cm−1. The frequency data confirm the centrosymmetry of the Sc(III) aquacomplex, contrary to earlier Raman results. The powder spectrum of crystallineSc(ClO4) 3 · 6H2O shows the above described Raman modes as well. Thesefindings are in contrast to Sc2(SO4)3 solutions, where sulfate replaces water inthe first hydration sphere and forms thermodynamically strong sulfato complexes.In ScCl3 solutions thermodynamically weak chloro complexes could be detected.Ab initio molecular orbital calculations were performed at the HF and MP2 levelsof theory using different basis sets up to 6–31 + G(d). Gas-phase structures,binding energies, and enthalpies are reported for the Sc3+(OH2)6 and Sc3+(OH2)7cluster. The Sc—O bond length for the Sc3+(OH2)6 cluster reproduces theexperimentally determined bond length of 2.18 A (recent EXAFS data) almost exactly.The theoretical binding energy for the hexaaqua Sc(III) ion was calculated andaccounts for ca. 54–59% of the experimental hydration enthalpy of Sc(III). Thethermodynamic stability of the Sc3+(OH2)6(OH2) cluster was compared to thatof the Sc3+(OH2)7 cluster, demonstrating that hexacoordination is inherently morestable than heptacoordination in the scandium (III) system. The calculated ν1ScO6frequency of the Sc+(OH2)6 cluster is ca. 12% lower than the experimentalfrequency. Adding an explicit second hydration sphere to give Sc3+ (OH2)18,denoted Sc[6 + 12], is shown to correct for the discrepancy. The frequencycalculation and the thermodynamic parameters for the Sc[6 + 12] cluster aregiven and the importance of the second hydration sphere is stressed. Calculatedfrequencies of the ScO6 subunit in the Sc[6 + 12] cluster agree very well withthe experimental values (for example, the calculated ν1ScO6 frequency was foundto be 447 cm−1, in excellent agreement with the above-reported experimentalvalue). The binding enthalpy for the Sc[6 + 12]cluster predicts the single ionhydration enthalpy to about 89%.

High-Field, Multifrequency EPR Study of the Vanadium(III) Hexaaqua Cation.

High-field, multifrequency EPR data are presented for vanadium(III)-doped CsGa(SO4)2·12X2O, where X = D or H, which afford the direct determination of the spin-Hamiltonian parameters pertaining to the 3Ag (S6) ground term. A pronounced change in the g values and zero-field splitting is observed upon isotopic substitution which cannot be simply explained using a conventional ligand field model.

Raman spectra of the α-alums CsM(SeO4)2·12H2O (M=Ga, In)

Low-temperature, polarized, single-crystal Raman spectra of the α-alum CsGa(SeO4) 2·12H2O were recorded to 1000 cm -1. The lattice modes, the external modes of water and the internal modes of [SeO4]2- , [Ga(H2O)6] 3+ and [Cs(H2O)6 ]+ were assigned. The unpolarized Raman spectrum of CsIn(SeO4)2·12H 2O was also recorded. The alums of Group 13 elements are optically transparent and suitable hosts for a wide range of trivalent hexaaqua cations. Copyright © 1999 John Wiley & Sons, Ltd.