Salt K2 Research Articles

Antimicrobial activity of supramolecular salts of gallium(III) and proflavine and the intriguing case of a trioxalate complex

The use of the gallium oxalate complex [Ga(ox)3]3− as a building block in the formation of a drug-drug salt with the antimicrobial agent proflavine (PF) as its proflavinium cation (HPF+), namely [HPF]3[Ga(ox)3]·4H2O, is reported together with the preparation of the potassium salt K3[Ga(ox)3] and the novel dimeric gallium(III) salt K4[Ga2(ox)4(μ-OH)2]·2H2O. All compounds have been characterized by solid state methods, and their performance as antimicrobial agents has been evaluated by disk diffusion assay against the bacteria strains Pseudomonas aeruginosa ATCC27853, Staphylococcus aureus ATCC25923, and Escherichia coli ATCC25922. While the [HPF]3[Ga(ox)3]·4H2O drug-drug salt is effective against all three strains, the gallium oxalate salt K3[Ga(ox)3] showed impressive selectivity towards P. aeruginosa, with little to no antimicrobial activity against the other two organisms. This work presents novel breakthroughs towards Ga based antimicrobial agents.

Synthesis and characterization of platinum(II) and palladium(II) diphosphine complexes with heterocyclic N-acetamide or saccharinate ligands

Abstract New palladium(II) and platinum(II) 1,1′-bis(diphenylphosphino) ferrocene (dppf) complexes with heterocyclic N-acetamide co-ligands [Pt(κ1-O-amp)(κ1-N-amp)(κ2-dppf)], [M(κ2-dap)(κ2-dppf)], (M= Pd, Pt, ampH = N-(2-pyridyl-3-methyl)acetamide, dapyH2 = 2,6-diacetamidopyridine) have been prepared and characterized. The salts K2[PtCl2(sac)2] and Na2[PdCl2(sac)2] have been prepared in excellent yield from the reactions of K2PtCl4 or Na2PdCl4 with Nasac in H2O or MeOH, respectively. Furthermore, the reaction products of the newly prepared salt, K2[PtCl2(sac)2] with diphosphines Ph2P(CH2)nPPh2 (n = 1–4), have been investigated.

Pretreatment of rice straw with recycled ionic liquids by phase-separation process for low-cost biorefinery.

An efficient ionic liquids (ILs) recycle technology will increase the economic viability of lignocellulosic biorefinery. The availability of recycling 1-butyl-3-methylimidazolium chloride for rice straw (RS) pretreatment was conducted. The kosmotropic salt K3 PO4 (TKP) solution was used as antisolvent for cellulose precipitation and forming a three-phase system consisting of biomass, ILs-rich, and salt-rich phases. The upper ILs phase and the bottom TKP phase were recycled without additional purification, which significantly simplifies the process for recovering ILs. Subsequently, the RS pretreated with multiple reusing ILs (RPRS) were investigated by components analysis, structure evolution, enzymatic hydrolysis, and fermentation experiments. The results showed that unpurified reusing ILs led to further delignification and improvement of enzyme accessibility of the pretreated RS. The reducing sugar yield of RS pretreated with 8th reusing IL (8th RPRS) could still reach 98.9%, and the ethanol and succinic acid concentrations achieved 91.9 and 29.3g/L by simultaneous saccharification and cofermentation. The present study demonstrated that the ILs recovered by phase-separation process could be used for RS pretreatment, and achieving high titer ethanol fermentation.

Terminal NiII−OH/−OH2 complexes in trigonal bipyramidal geometries derived from H2O

The preparation and characterization of two NiII complexes are described, a terminal NiII–OH complex with the tripodal ligand tris[(N)-tert-butylureaylato)-N-ethyl)]aminato ([H3buea]3−) and a terminal NiII–OH2 complex with the tripodal ligand N,N′,N″-[2,2′,2″-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido) ([MST]3−). For both complexes, the source of the –OH and –OH2 ligand is water. The salts K2[NiIIH3buea(OH)] and NMe4[NiIIMST(OH2)] were characterized using perpendicular-mode X-band electronic paramagnetic resonance, Fourier transform infrared, UV–vis spectroscopies, and its electrochemical properties were evaluated using cyclic voltammetry. The solid state structures of these complexes determined by X-ray diffraction methods reveal that they adopt a distorted trigonal bipyramidal geometry, an unusual structure for 5-coordinate NiII complexes. Moreover, the NiII–OH and NiII–OH2 units form intramolecular hydrogen bonding networks with the [H3buea]3− and [MST]3− ligands. The oxidation chemistry of these complexes was explored by treating the high-spin NiII compounds with one-electron oxidants. Species were formed with S=1/2 spin ground states that are consistent with formation of monomeric NiIII species. While the formation of NiIII–OH complexes cannot be ruled out, the lack of observable O–H vibrations from the putative Ni–OH units suggest the possibility that other high valent Ni species are formed.

Theoretical study of the redox reactivity of complex boron hydrides K2[B12H12], Cs2[B12H12], and Tl2[B10H10] and their mixed salts K2[B12H12] • KCl, Cs2[B12H12] • CsCl, and Tl2[B10H10] • KNO3

The ability of K2[B12H12], Cs2[B12H12], and Tl2[B10H10] molecules to act as the oxidant of n-octane in the gas phase has been considered in comparison with the O2, HNO3, and KNO3 molecules. Calculations have been performed at the B3LYP/6-31G*//6-311+G* + LanL2Dz level. Notwithstanding the fact that model calculations of isolated K2[B12H12], Cs2[B12H12], and Tl2[B10H10] molecules only approximately reflect the properties of solid K2[B12H12], Cs2[B12H12], and Tl2[B10H10], such a consideration makes it possible to reveal the molecular analogue of the “salt” effect: the oxidative ability of mixed salts K2[B12H12] • KCl, Cs2[B12H12] • CsCl, and Tl2[B10H10] • KNO3, in terms of the difference of the electronic chemical potentials of the oxidant and reductant, as well as of estimated electron density transfer, turns out to be similar to the oxidative ability of pure K2[B12H12], Cs2[B12H12], and Tl2[B10H10].

Palladium(IV) in an Oxoanionic Environment: The XeF2 Assisted Synthesis of [Pd(S2 O7 )3 ](2.).

For the first time tetravalent palladium is detected, coordinated exclusively by simple oxoanions. Stabilization was achieved by formation of the [Pd(S2 O7 )3 ](2-) complex in which three chelating disulfate groups surround the metal atom. The salt K2 [Pd(S2 O7 )3 ] could only be obtained if the reaction of K2 [PdCl6 ] and neat SO3 was performed in the presence of XeF2 .

PENGARUH KUALITAS BAHAN BAKU DAN RASIO UMPAN TERHADAP PELARUT PADA PROSES PEMURNIAN GARAM DENGAN METODE HIDROEKSTRAKSI BATCH

Nowadays, Indonesia is still relying on the imported salt, especially from Australia to meet the domestic salt demand. Development of salt purification process is still ventured to improve the quality of the salt as well as the efficiency. In this research, salt purification process is done using the hydroextraction method, where the salt crystals are purified using the pure saturated salt solution in a beaker glass. Different classification of salt K1, K2, and K3 are used with F:S ratio is varied by 1:30; 1:35; 1:40; 1:45; and 1:50. The hydroectraction process is stirred at 50 rpm. The quality of the purified salt are determined based on analysis of the levels of NaCl, Ca2+, and Mg2+. The highest NaCl level, 98,89% obtained on the process using K2 salt with F:S ratio is 1:45.

Uranium(III) redox chemistry assisted by a hemilabile bis(phenolate) cyclam ligand: uranium-nitrogen multiple bond formation comprising a trans-{RN═U(VI)═NR}(2+) complex.

A new monoiodide U(III) complex anchored on a hexadentate dianionic 1,4,8,11-tetraazacyclotetradecane-based bis(phenolate) ligand, [U(κ(6)-{((tBu2)ArO)2Me2-cyclam})I] (1), was synthesized from the reaction of [UI3(THF)4] (THF = tetrahydrofuran) and the respective potassium salt K2((tBu2)ArO)2Me2-cyclam and structurally characterized. Reactivity of 1 toward one-, two-, and four-electron oxidants was studied to explore the reductive chemistry of this new U(III) complex. Complex 1 reacts with one-electron oxidizers, such as iodine and TlBPh4, to form the seven-coordinate cationic uranium(IV) complexes [U(κ(6)-{((tBu2)ArO)2Me2-cyclam})I][X] (X = I (2-I), BPh4 (2-BPh4)). The new uranium(III) complex reacts with inorganic azides to yield the pseudohalide uranium(IV) complex [U(κ(6)-{((tBu2)ArO)2Me2-cyclam})(N3)2] (4) and the nitride-bridged diuranium(IV/IV) complex [(κ(4)-{((tBu2)ArO)2Me2-cyclam})(N3)U(μ-N)U(κ(5)-{((tBu2)ArO)2Me2-cyclam})] (5). Two equivalents of [U(κ(6)-{((tBu2)ArO)2Me2-cyclam})I] (1) effect the four-electron reduction of 1 equiv of PhN═NPh to form the bis(imido) complex [U(κ(4)-{((tBu2)ArO)2Me2-cyclam})(NPh)2] (6) and the U(IV) species 2-I. Moreover, the hemilability of the hexadentate ancillary ligand ((tBu2)ArO)2Me2-cyclam(2-) allows to perform the reductive cleavage of azobenzene with an unprecedented formation of a trans-bis(imido) complex. The complexes were characterized by NMR spectroscopy, and all the new uranium complexes were structurally authenticated by single-crystal X-ray diffraction.

Antioxidant activity of humic substances via bioluminescent monitoring in vitro.

FMN-oxidoreductase and bacterial luciferase was used as a bioassay in vitro to monitor toxicity of the oxidizer solutions. Toxicities of general and oxidative types were evaluated using bioluminescent kinetic parameters-bioluminescence intensity and induction period, respectively. Antioxidant activity of HS was attributed to their ability to decrease both general and oxidative toxicities; the HS antioxidant efficiency was characterized with detoxification coefficients D GT and D OxT, respectively. Dependencies of D GT and D OxT on HS concentration and time of preliminary incubation of the oxidizers with HS were demonstrated. The optimal conditions for detoxification of the oxidizers were >20-min incubation time and 0.5 × 10(-4) to 2 × 10(-4) M of HS concentration. The present study promotes application of the enzymatic luminescent bioassay to monitor toxicity of pollutants of oxidative nature in environmental and waste waters in remediation procedures.

Synthesis and crystal structure of K3[NpO4(OH)2

Attempts were made to isolate anhydrous compounds of [NpO4(OH)2]3− anions with heavy alkali metal cations (K, Rb, Cs) by crystallization at elevated temperatures, and the salt K3[NpO4(OH)2] was isolated and studied. Crystals of K3[NpO4(OH)2] consist of tetragonal bipyramidal [NpO4(OH)2]3− anions and K+ cations. The [NpO4(OH)2]3− anion occupies the position in the symmetry center. The Np-O distances in this anion are 1.8992(7) and 1.9100(7) A in the equatorial plane of the bipyramid and 2.3231(8) A with OH groups. The OH hydrogen atoms participate in weak H bonds [O⋯O 3.0250(11) A] linking the anions in layers [NpO4(OH)2] 3− parallel to the (010) plane. In the interlayer space, there are two crystallographically different K atoms. Their coordination number (CN) can be considered to be equal to 7 and 8. Comparison with the structures of the known compounds Na3[NpO4(OH)2] and K3[NpO4(OH)2]·2H2O was made. The structure of the latter compound was redetermined with higher accuracy. The failure of attempts to prepare the anhydrous rubidium and cesium compounds is probably due to large ionic radius of these cations, requiring high coordination number.

Reactions of K2[Fe3Q(CO)9] (Q = Se, Te) with AsI3: Synthesis and Structures of the First {Fe3TeAs} Clusters with Capping µ3-AsI and Bridging µ6,κ3:κ3-As2 Ligands

Reactions of cluster salts K2[Fe3Q(CO)9] (Q = Se, Te) with AsI3 in CH2Cl2 proceed differently depending on the chalcogen atom and the reaction conditions. For Te, the product of addition of μ3-AsI vertex to the initial cluster, [Fe3(CO)9(μ3-Te)(μ3-AsI)] (2b) is the main component of the solution. By action of traces of water, such as wet silica gel, 2b is converted to a dimeric cluster [{Fe3(CO)9(μ3-Te)}2(μ6,κ3:κ3-As2)] (5), whose molecules contain two identical square-pyramidal cores joined by diarsane moiety. For Se, the product 2a, analogous to 2b, was only found on the basis of mass-spectra, as main component of the reaction solution, but could not be separated because of its instability and similarity of its properties to those of [Fe3(CO)9Se2], a by-product. Two other products, [Fe3(CO)9(μ3-Se)(µ4,κ3:κ2-AsSe)Fe2(CO)6(μ-I)] (3) and K[{Fe3(CO)9(μ3-Se)(μ4-As)}2Fe(CO)3I] (4) were only found as little amount of crystals. The molecule of 3 consists of the pyramidal {Fe3SeAs} core linked by the As–Se bond to a {Fe2SeI} fragment. The cluster anion in 4 consists of two {Fe3SeAs} cores joined via the {Fe(CO)3I} unit. The products 3 and 4 presumably originate from the dissociation of the initial cluster core and their formation correlates with lower stability of Se-containing cluster 2a as compared to 2b.

Low-dimensional compounds containing cyanido groups. XXIV. Crystal structure, spectroscopic and thermal properties of two Cu(II) tetracyanidoplatinate complexes with tetradentate N-donor ligands

Violet crystals of [Cu2(teta)2Pt(CN)4]2[Pt(CN)4]2 (1, teta=N,N’-bis(2-aminoethyl)-1,2-diaminoethane; triethylenetetramine) and {[Cu3(bapen)3Pt(CN)4][Pt(CN)4]2·13H2O}n (2, bapen=N,N′-bis(3-aminopropyl)-1,2-diaminoethane) were crystallized from the water–methanol or aqueous solutions containing Cu(II) salt, teta or bapen ligand and K2[Pt(CN)4]. Both compounds were characterized using elemental analysis, IR and UV–Vis spectroscopy, thermal and X-ray crystal structure analysis. Two ν(CN) absorption bands in the IR spectra of the complexes imply non-equivalency of cyanido groups meaning the presence of both, terminal and bridging ones and together with the results of elemental analysis indicate simple chain-like structure. Thermal decompositions of the prepared complexes are few-step processes which comprise liberation of crystal water (only for 2), decay of N-donor ligands L and release of cyanido groups. Finally, an X-ray crystal structure analysis has shown their complicated crystal structures. On one hand, complex 1 is of ionic character and is formed from a couple of trinuclear [Cu(teta)-Pt(CN)4-Cu(teta)]2+ complex cations and a couple of discrete [Pt(CN)4]2− anions. On the other hand, complex 2 is of polymeric character and is formed by 1D chains of {[Cu3(bapen)3Pt(CN)4]4+}n composition, 2n single [Pt(CN)4]2− anions and 13n molecules of crystal water.

Kalium-Doppelsalze mit den gemischten Trisulfidometallat-Ionen [MoOS3]2- und [WOS3]2- / Potassium Double Salts with the Mixed Trisulfidometalate Ions [MoOS3]2- and [WOS3]2-

In the course of the synthesis of mixed oxidosulfido molybdates and tungstates by passing H2S gas through solutions of the oxido metalates, several new salts containing the metalates [MOS3]2- besides further anions (halides X-, hydrosulfide SH- or thiosulfate S2O2- 3) were obtained as well-formed crystals. Their crystal structures have been determined using single crystal X-ray data. The salts containing SH- as the additional anion crystallize with a new structure type (orthorhombic, space group Pmn21, M=Mo=W, TM =20=-125 °C: a=957.7(2)/954.15(2), b=636.2(2)/636.19(1), c=812.4(2)/809.88(2) pm, Z =2, R1=0.0319=0.0185). The mixed sulfidomolybdate/ chloride K3[MoO1.25S2.75]Cl (orthorhombic, space group Pca21, a=1246.3(1), b=623.20(4), c=1230.44(8) pm, Z =4, R1=0.0472) is isotypic with the sulfidotungstate K3[WOS3]Cl, but contains 25% of the disulfido molybdate. The structures of the SH- and the Cl- salts are closely related: In both cases, the trisulfido metalates are overall coordinated by cuboctahedra of 12 K+ ions, and the small additional anions are centered in K+ octahedra. In this regard, the structures are both derivatives of the cubic perovskite (and thus the Cu3Au) type. This crystallographic group-subgroup relation is discussed in detail. Yellow hexagonal columns of the double salt K6[WOS3]2(S2O3) were obtained by the methanothermal decomposition of the disulfidotungstate K2[WO2S2]. It crystallizes with a new structure type (hexagonal, space group P63mc, a=983.78(8), c=1227.3(1) pm, Z =2, R1=0.0175). Like in the other mixed salts, the two crystallographically different [WOS3]2- anions exhibit an overall cuboctahedral coordination by 12 potassium cations. The smaller S2O2- 3 anions are surrounded by nine K+ ions arranged in the form of two flat facesharing octahedra. Again similar to the mixed halides and hydrosulfides, the two K polyhedra around the anions, here present in a 2 : 1 ratio, are arranged in a space-filling packing, in this case related to the ht- BaMnO3 (and thus the Ni3Ti) structure type. According to their ‘double salt’ character, the Mo/W-O and Mo/W-S distances and the intramolecular vibrational frequencies of the tetrahedral moieties of the title compounds are similar between them and those in the pure potassium trisulfido metalates. This further becomes apparent from the additive nature of their molar volumes, which correspond to the sum of the volumes of the simple salts KCl, KSH or K2(S2O3) and K2[MoOS3].

Chalcogen arsenide clusters of iron with a functional carboxyl group: Synthesis, structures, and thermolysis

The carbonyl clusters [Fe3(μ3-Q)(μ3-AsR)(CO)9] (Q = Se and Te; R = meta- and para-HOOCC6H4) were obtained from the salts K2[Fe3(μ3-Q)(CO)9] and organoarsenic diiodides RAsI2 prepared by reducing iodination of arsonic acids RAsO(OH)2 according to a novel method. The structures of the clusters were identified by X-ray diffraction. The crystal packing motifs of the dimers of the cluster molecules and their relationship with the solubility of the clusters are discussed. The sequential steps of the thermolysis (decarbonylation, decarboxylation, and decomposition of the organic fragment) of the clusters were studied. The presence and location of the carboxyl group does not influence the decarbonylation temperature.

Hydrates of the Alkali Trioxidomonosulfidomolybdates and -tungstates: K2[(Mo/W)O3S] · 1.5H2O and (Rb/Cs)2[(Mo/W)O3S] · H2O

Abstract The trioxidomonosulfidomolybdate and -tungstate anions [(Mo/W)O3S]2– are the first products formed when passing H2S gas through a solution of the oxidometalates. Their potassium, rubidium and cesium salt hydrates form as crystalline precipitates from these solutions depending on pH, the polarity of the solvent, educt concentrations and temperature. The structures of the sesqui- (K) and mono- (Rb, Cs) hydrates have been determined by means of X-ray single crystal diffraction data. The potassium sesquihydrates K2[(Mo/W)O3S] · 1.5H2O are isotypic and crystallize with a new structure type (monoäclinic, space group C2/c, M = Mo/W: a = 987.0(2)/993.13(11), b = 831.75(14)/831.10(11), c = 1868.9(4)/1865.2(2) pm, β = 99.34(2)/99.153(8)°, R1 = 0.0352/0.0390). In the crystal structure the [(Mo/W)O3S]2– anions are connected via hydrogen bonds to form columns along the c direction. Channels containing only water molecules run along the [101] direction. The dehydration process proceeds in a topotactic reaction between 60 to 95 °C and yields crystals of the anhydrous salts K2[(Mo/W)O3S]. The two different K+ cations exhibit a 5 + 3 and 5 + 2 O/S coordination. The heavier alkali metal cations form the four monohydrates (Rb/Cs)2[(Mo/W)O3S] · H2O (trigonal rhombohedral, space group R-3m) with lattice parameters for the Rb/Cs molybdates of a = 621.17(6)/624.62(10), c = 3377.9(4)/3388.6(8) pm (R1 = 0.0505/0.0734) and the tungstates of a = 642.80(3)/643.3(4), c = 3532.8(3)/3566(4) pm (R1 = 0.0348/0.0660). In the structures the 3m symmetrical tetrahedra are arranged to form double layers in such a way, that the O3 bases of the tetrahedra are pointing towards each other in a staggered conformation. These double layers are stacked in the c direction in a rhombohedral sequence. In these hydrates, there are no distinct hyrdogen bonds. Instead, partially disordered pairs of H2O molecules are situated in large cavities between the double layers. With a number of 10, the cation coordination sphere is increased compared to the K salts. The crystallographic results are confirmed by vibrational spectroscopy (Raman/IR) and thermal analytical studies of the new compounds.

Ditopic tris(2-mercaptoimidazol-1-yl)borate ligands and their coordination behavior toward [Ru(p-cymene)]2+

The ditopic tris(2-mercaptoimidazol-1-yl)borate ligand K2[(mtEt)3B–B(mtEt)3] cannot be prepared from B2(NMe2)4/4 HmtEt/2 KmtEt, because the stable intramolecular diadduct (mtEt)B(μ-mtEt)2B(mtEt) is generated instead (HmtEt=2-mercapto-1-ethylimidazole). Introduction of a meta- or para-phenylene spacer between the two boron atoms precludes the 2-mercaptoimidazol-1-yl groups from adopting a bridging position so that the potassium salts K2[(mtEt)3B-(m-C6H4)-B(mtEt)3] and K2[(mtEt)3B-(p-C6H4)-B(mtEt)3] become readily accessible. These ligands react with [(p-cym)RuCl2]2 to give the dinuclear RuII complexes [(p-cym)Ru(mtEt)3B-(m-C6H4)-B(mtEt)3Ru(p-cym)]Cl2 and [(p-cym)Ru(mtEt)3B-(p-C6H4)-B(mtEt)3Ru(p-cym)]Cl2 (p-cym=p-cymene). After the exchange of the Cl− counterions for [PF6]−, both complexes have been crystallized and structurally characterized by X-ray diffraction.

ChemInform Abstract: Homoatomic Polyanions of Post-Transition Elements. Synthesis, Structure, and Characterization of the Paramagnetic Nonagermanide (3-) Ion Ge3- 9, a C2v Cluster with an Odd Skeletal Electron Count.

The salt K3(2,2,2-cryptand)3(PPh3)3Ge9 has been obtained by complexation of the KGe1.8 alloy by 2,2,2-cryptand in ethylenediamine with solute triphenylphosphine. The structure of the anion has been determined crystallographically and the results are supported by EPR and extended Huckel calculations.

Compounds with the Electron-Rich [W6Cl18]2− Cluster Anion

Cluster compounds of the general formula A(2)[W(6)Cl(18)] containing singly charged A cations (A = K, Rb, Ag, Tl, NH(4), N(C(2)H(5))(4), N(n-C(3)N(7))(4), N(n-C(4)H(9))(4)) and [W(6)Cl(18)](2-) anions have been synthesized. Compounds were obtained by W(6)Cl(18) reduction using methanol and the corresponding metal or (alkyl-)ammonium salts. The use of CoCp(2) as reducing agent in inert solvents such as tetrahydrofurane also leads to the ionic compound (Co(C(5)H(5))(2))(2)[W(6)Cl(18)]. All compounds described here evidence the existence of octahedral clusters of the M(6)X(12) type with 20 cluster electrons occupying metal centered states, thus exceeding the conventional number of 16 electrons for this cluster type. Electrospray ionization (ESI) mass spectra were recorded for the neutral compound W(6)Cl(18) and for the ionic salts K(2)[W(6)Cl(18)], Cs(2)[W(6)Cl(18)], and (Co(C(5)H(5))(2))(2)[W(6)Cl(18)], showing that the cluster W(6)Cl(18) unit in these compounds is preserved in solution. The base peak in the ESI spectra for all compounds corresponds to the [W(6)Cl(18)](2-) anion, so that neutral W(6)Cl(18) is prone to undergo a two electron reduction process. This result is confirmed by cyclic voltammetry experiments, which makes of W(6)Cl(18) a very clean mild oxidizing agent. The preparation of the complete series of ionic A(2)[W(6)Cl(18)] (A = K, Cs, CoCp(2)) clusters allows to systematically investigate their structural trends as function of the distinctive cations, which is the main focus of the present work.

Structural features in Tutton's salts K2[M2+(H2O)6](SO4)2, with M2+ = Mg, Fe, Co, Ni, Cu, and Zn

The crystal chemistry of six crystals of general formula K 2 [M 2+ (H 2 O) 6 ](SO 4 ) 2 , with M 2+ = Mg, Fe, Co, Ni, Cu, and Zn, was investigated by single-crystal structure analysis to determine the effects of the chemical variation of M 2+ on the structural environment surrounding K, M, and S sites. Results indicate that the distortion in the SO 4 tetrahedron and the MO 6 octahedron is very small, except for CuO 6 where it is pronounced because of the Jahn-Teller effect. The KO 8 -octacoordinate polyhedron has the highest degree of distortion, and its idealized shape may be referred to as a bicapped trigonal prism. The SO 4 size is not affected by changes in cation occupancies at the adjacent M site. In contrast, changes in the KO 8 size, which are accompanied by changes in the bond valence sum at K, depend on interaction with the first and second coordination sphere of M. This interaction results by changes in M-O individual lengths, by expansion of the second coordination sphere of M, and by changes in the distribution of the bond strengths over the O atoms coordinated to K. The MO 6 size follows the expected trend from the increased ionic radius at the M site. The latter is also correlated with the unit-cell volume except for the Cu- and Mg-phase, which show a larger cell volume with respect to that expected. Although the relevant octahedral distortion around the Cu 2+ cation explains the volume excess in the Cu-phase, an expansion of the second coordination sphere of Mg 2+ , compared to those of cations of larger ionic radius (such as Zn and Co), explains the excess of the unit-cell volume in the Mg-phase. As the CuO 6 distortion can be caused by the Jahn-Teller effect, the higher ionicity of the Mg atom could be the cause for its anomalous behavior observed in Tutton’s salts. This stereochemical behavior of the Mg atom seems to be consistent with the weakening of the hydrogen bonds in the structure connected to differences in the bonding character of Mg and transition metals when coordinated by water molecules.

Synthesis and Structural Characterization of a New Nanoporous‐Like Keggin Heteropolyanion Salt: K3(H2O)4 [H2SiVW11O40] (H2O)8+x.

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