An Old Crystallization Technique as a Fast, Facile, and Adaptable Method for Obtaining Single Crystals of Unstable "Li2TCNQF4" and New Compounds of TCNQ or TCNQF4: Syntheses, Crystal Structures, and Magnetic Properties.

Detailed structural information is essential for understanding the properties of TCNQ and TCNQF4 compounds (TCNQ = 7,7,8,8-tetracyanoquinodimethane; TCNQF4 = 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane). The ineludible requirement of obtaining crystals of a size and quality sufficient to yield a successful X-ray diffraction analysis has been challenging to satisfy because of the instability of many of these compounds in solution. Crystals of two new complexes of TCNQ, [trans-M(2ampy)2(TCNQ)2] [M = Ni (1), Zn (2); 2ampy = 2-aminomethylpyridine], as well as unstable [Li2(TCNQF4)(CH3CN)4]·CH3CN (3), can be prepared in minutes by a horizontal diffusion technique and can be harvested easily for X-ray structural studies. Compound 3, previously described as "Li2TCNQF4," forms a one-dimensional (1D) ribbon. Compounds 1 and 2 can also be obtained as microcrystalline solids from methanolic solutions of MCl2/LiTCNQ/2ampy. Their variable-temperature magnetic studies confirmed a contribution of strongly antiferromagnetically coupled pairs of TCNQ•- anion radicals at higher temperatures with exchange coupling J/kB = -1206 K and J/kB = -1369 K for 1 and 2, respectively, estimated using a spin dimer model. The presence of magnetically active anisotropic Ni(II) atoms with S = 1 in 1 was confirmed, and the magnetic behavior of 1, representing an infinite chain of alternating S = 1 sites and S = 1/2 dimers, was described by a spin-ring model suggesting ferromagnetic exchange coupling between Ni(II) sites and anion radicals.

Triangulo-{ErIII 3} complex showing field supported slow magnetic relaxation.

The triangulo-{Er3} complex [Er3Cl(o-van)3(OH)2(H2O)5]Cl3·nH2O (n = 9.4; H(o-van) = o-vanillin) (1) was generated by an in situ method. The isolated Er(iii) complex 1 was characterized by elemental analysis and molecular spectroscopy. The results of single crystal X-ray diffraction studies have shown that 1 is built up of trinuclear [Er3Cl(o-van)3(OH)2(H2O)5]3+ complex cations, chloride anions and water solvate molecules. Within the complex cation the three Er(iii) central atoms are placed at the apexes of a triangle which are bridged by three (o-van)- ligands with additional chelating functions and two µ3-OH- ligands. Additionally five aqua and one chlorido ligands complete the octa-coordination of the three Er(iii) atoms. AC susceptibility measurements reveal that the compound exhibits slow magnetic relaxation with two relaxation modes.

Slow magnetic relaxation in Ni-Ln (Ln = Ce, Gd, Dy) dinuclear complexes.

Three new isomorphous complexes [Ni(o-van-en)LnCl3(H2O)] [H2(o-van-en) = N,N'-ethylene-bis(3-methoxysalicylaldiminate; Ln = Ce (1), Gd (2), Dy (3)] were prepared by a stepwise reaction using mild conditions and were structurally characterised as dinuclear molecules in which Ni and Ln are coordinated by the compartmental Schiff base ligand (o-van-en)= and doubly bridged by O atoms. While the nickel(ii) centre is diamagnetic within the N2O2 square-planar coordination of the Schiff base ligand, the lanthanide atoms are octa-coordinated to give an {LnCl3O5} chromophore with a fac-arrangement of the chlorido ligands. AC magnetic measurements revealed that all three complexes, including the nominally isotropic Gd(iii) system, show field induced slow magnetic relaxation with two or three relaxation channels: at T = 1.9 K the low-frequency relaxation time is τLF(1) = 0.060 s at BDC = 0.5 T, τLF(2) = 0.37 s at BDC = 0.3 T, and τLF(3) = 1.29 s at BDC = 0.15 T.

Polymorphism of the dinuclear CoIII-Schiff base complex [Co2(o-van-en)3]·4CH3CN (o-van-en is a salen-type ligand).

Reactions of Co(OH)2 with the Schiff base bis(2-hydroxy-3-methoxybenzylidene)ethylenediamine, denoted H2(o-van-en), under different conditions yielded the previously reported complex aqua[bis(3-methoxy-2-oxidobenzylidene)ethylenediamine]cobalt(II), [Co(C18H18N2O4)(H2O)], 1, under anaerobic conditions and two polymorphs of [µ-bis(3-methoxy-2-oxidobenzylidene)ethylenediamine]bis{[bis(3-methoxy-2-oxidobenzylidene)ethylenediamine]cobalt(III)} acetonitrile tetrasolvate, [Co2(C18H18N2O4)3]·4CH3CN, i.e. monoclinic 2 and triclinic 3, in the presence of air. Both novel polymorphs were chemically and spectroscopically characterized. Their crystal structures are built up of centrosymmetric dinuclear [Co2(o-van-en)3] complex molecules, in which each CoIII atom is coordinated by one tetradentate dianionic o-van-en ligand in an uncommon bent fashion. The pseudo-octahedral coordination of the CoIII atom is completed by one phenolate O and one amidic N atom of the same arm of the bridging o-van-en ligand. In addition, the asymmetric units of both polymorphs contain two acetonitrile solvent molecules. The polymorphs differ in the packing orders of the dinuclear [Co2(o-van-en)3] complex molecules, i.e. alternating ABABAB in 2 and AAA in 3. In addition, differences in the conformations, the positions of the acetonitrile solvent molecules and the pattern of intermolecular interactions were observed. Hirshfeld surface analysis permits a qualitative inspection of the differences in the intermolecular space in the two polymorphs. A knowledge-based study employing Full Interaction Maps was used to elucidate possible reasons for the polymorphism.

Exceptionally slow magnetic relaxation in cobalt(ii) benzoate trihydrate.

Cobalt(ii) benzoate trihydrate prepared by the reaction of CoCO3 with benzoic acid (HBz) in boiling water followed by crystallization has been structurally characterized as a chain-like system with the formula unit [Co(Bz)(H2O)2]Bz·H2O where the Co(ii) atoms are triply linked by one bridging syn-syn benzoato (Bz) and two aqua ligands; additional benzoate counter ions and solvate water molecules are present in the crystal structure. DC magnetic measurements reveal a sizable exchange coupling of a ferromagnetic nature between the Co(ii) atoms. At TN = 5.5 K the paramagnetic phase switches to the antiferromagnetic phase. Though the remnant magnetization is zero, the magnetization curve shows two lobes of a hysteresis loop and the DC relaxation experiments confirm a long relaxation time at T = 2.0 K. AC susceptibility data confirm a slow relaxation of magnetization even in the antiferromagnetic phase. In the absence of the magnetic field, two relaxation channels exist. The relaxation time for the low frequency channel is as slow as τLF > 1.6 s and data fitting yields τLF (2.1 K) = 14 s. The high-frequency relaxation time obeys the Orbach process at a higher temperature whereas the Raman process dominates the low-temperature region. Three slow relaxation channels are evidenced at the applied magnetic field BDC = 0.1 T.

Disorder of the dimeric TCNQ-TCNQ unit in the crystal structure of [Ni(bpy)3]2(TCNQ-TCNQ)(TCNQ)2·6H2O (TCNQ is 7,7,8,8-tetra-cyano-quinodi-methane).

Crystallization from an aqueous methanol system composed of Ni(NO3)2, 2,2'-bipyridine (bpy) and LiTCNQ (TCNQ is 7,7,8,8-tetra-cyano-quinodi-methane) in a 1:3:2 molar ratio yielded single crystals of bis-[tris-(2,2'-bi-pyridine-κ2N,N')nickel(II)] bis-(7,7,8,8-tetra-cyano-quinodi-methane radical anion) bi[7,7,8,8-tetra-cyano-quino-dimethanide] hexa-hydrate, [Ni(C10H8N2)3]2(C24H8N8)(C12H4N4)2·6H2O or [Ni(bpy)3]2(TCNQ-TCNQ)(TCNQ)2·6H2O. The crystal structure comprises [Ni(bpy)3]2+ complex cations, two centrosymmetric crystallographically independent TCNQ ·- anion radicals with π-stacked exo groups, and an additional dimeric TCNQ-TCNQ unit which comprises 75.3 (9)% of a σ-dimerized (TCNQ-TCNQ)2- dianion and 24.7 (9)% of two TCNQ·- anion radicals with tightly π-stacked exo groups. The title complex represents the first example of an NiII complex containing a σ-dimerized (TCNQ-TCNQ)2- dianion. Disordered solvent water mol-ecules present in the crystal structure participate in hydrogen-bonding inter-actions.

Synthesis, crystal structure and magnetic properties of (acetato-κ²O,O')bis(5,5'-dimethyl-2,2'-bipyridine-κ²N,N')nickel(II) perchlorate monohydrate.

The title hydrated ionic complex, [Ni(CH3COO)(C12H12N2)2]ClO4·H2O or [Ni(ac)(5,5'-dmbpy)2]ClO4·H2O (where 5,5'-dmbpy is 5,5'-dimethyl-2,2'-bipyridine and ac is acetate), (1), was isolated as violet crystals from the aqueous ethanolic nickel acetate-5,5'-dmbpy-KClO4 system. Within the complex cation, the Ni(II) atom is hexacoordinated by two chelating 5,5'-dmbpy ligands and one chelating ac ligand. The mean Ni-N and Ni-O bond lengths are 2.0628 (17) and 2.1341 (15) Å, respectively. The water solvent molecule is disordered over two partially occupied positions and links two complex cations and two perchlorate anions into hydrogen-bonded centrosymmetric dimers, which are further connected by π-π interactions. The magnetic properties of (1) at low temperatures are governed by the action of single-ion anisotropy, D, which arises from the reduced local symmetry of the cis-NiO2N4 chromophore. The fitting of the variable-temperature magnetic data (2-300 K) gives g(iso) = 2.134 and D/hc = 3.13 cm(-1).

Synthesis, characterization and crystal structure of the new pentahydrate of bis(2,2'-bipyridine-κ(2)N,N')(oxalato-κ(2)O(1),O(2))nickel(II).

The reaction of NiCl2, K2C2O4·H2O and 2,2'-bipyridine (bpy) in water-ethanol solution at 281 K yields light-purple needles of the new pentahydrate of bis(2,2'-bipyridine)oxalatonickel(II), [Ni(C2O4)(C10H8N2)2]·5H2O or [Ni(ox)(bpy)2]·5H2O, while at room temperature, deep-pink prisms of the previously reported tetrahydrate [Ni(ox)(bpy)2]·4H2O [Román, Luque, Guzmán-Miralles & Beitia (1995), Polyhedron, 14, 2863-2869] were gathered. The asymmetric unit in the crystal structure of the new pentahydrate incorporates the discrete molecular complex [Ni(ox)(bpy)2] and five solvent water molecules. Within the complex molecule, all three ligands are bonded as chelates. The complex molecules are involved in an extended system of hydrogen bonds with the solvent water molecules. Additionally, π-π interactions also contribute to the stabilization of the extended structure. The dehydration of the pentahydrate starts at 323 K and proceeds in at least two steps as determined by thermal analysis.

Crystal structure and thermal properties of a square-planar Ni(II) complex of cyanide and a tricyclic bis-amidine ligand formed in situ under solvothermal conditions.

The reaction of N(1),N(1')-(ethane-1,2-diyl)bis(propane-1,3-diamine) (bapen), K2[Ni(CN)4]·H2O and dimethylformamide in the presence of Gd(NO3)3·6H2O under solvothermal conditions yielded yellow crystals of dicyanido(2,3,4,6,7,9,10,11-octahydropyrimido[2',1':3,4]pyrazino[1,2-a]pyrimidine)nickel(II) hemihydrate, [Ni(CN)2(C10H16N4)]·0.5H2O, (I), the crystal structure of which is composed of [Ni(CN)2(pdpm)] molecules (pdpm is 2,3,4,6,7,9,10,11-octahydropyrimido[2',1':3,4]pyrazino[1,2-a]pyrimidine) on general positions linked by O-H···N hydrogen bonds to water molecules located on twofold axes. This structural unit is further linked by nonclassical C-H···N interactions to form a warped two-dimensional net perpendicular to the unit-cell b axis. The nets are stacked, with C-H···O contacts joining successive units. The Ni(II) cation is coordinated with square-planar geometry by a chelating pdpm ligand and two cyanide ligands in mutually cis positions. Complex (I) is stable up to 360 K, at which point dehydration takes place; the ligands start to decompose at 558 K.

Thermal decomposition of [Co(en)3][Fe(CN)6]∙ 2H2O: Topotactic dehydration process, valence and spin exchange mechanism elucidation.

BACKGROUND: The Prussian blue analogues represent well-known and extensively studied group of coordination species which has many remarkable applications due to their ion-exchange, electron transfer or magnetic properties. Among them, Co-Fe Prussian blue analogues have been extensively studied due to the photoinduced magnetization. Surprisingly, their suitability as precursors for solid-state synthesis of magnetic nanoparticles is almost unexplored. In this paper, the mechanism of thermal decomposition of [Co(en)3][Fe(CN)6] ∙∙ 2H2O (1a) is elucidated, including the topotactic dehydration, valence and spins exchange mechanisms suggestion and the formation of a mixture of CoFe2O4-Co3O4 (3:1) as final products of thermal degradation. RESULTS: The course of thermal decomposition of 1a in air atmosphere up to 600°C was monitored by TG/DSC techniques, (57)Fe Mössbauer and IR spectroscopy. As first, the topotactic dehydration of 1a to the hemihydrate [Co(en)3][Fe(CN)6] ∙∙ 1/2H2O (1b) occurred with preserving the single-crystal character as was confirmed by the X-ray diffraction analysis. The consequent thermal decomposition proceeded in further four stages including intermediates varying in valence and spin states of both transition metal ions in their structures, i.e. [Fe(II)(en)2(µ-NC)Co(III)(CN)4], Fe(III)(NH2CH2CH3)2(µ-NC)2Co(II)(CN)3] and Fe(III)[Co(II)(CN)5], which were suggested mainly from (57)Fe Mössbauer, IR spectral and elemental analyses data. Thermal decomposition was completed at 400°C when superparamagnetic phases of CoFe2O4 and Co3O4 in the molar ratio of 3:1 were formed. During further temperature increase (450 and 600°C), the ongoing crystallization process gave a new ferromagnetic phase attributed to the CoFe2O4-Co3O4 nanocomposite particles. Their formation was confirmed by XRD and TEM analyses. In-field (5 K / 5 T) Mössbauer spectrum revealed canting of Fe(III) spin in almost fully inverse spinel structure of CoFe2O4. CONCLUSIONS: It has been found that the thermal decomposition of [Co(en)3][Fe(CN)6] ∙∙ 2H2O in air atmosphere is a gradual multiple process accompanied by the formation of intermediates with different composition, stereochemistry, oxidation as well as spin states of both the central transition metals. The decomposition is finished above 400°C and the ongoing heating to 600°C results in the formation of CoFe2O4-Co3O4 nanocomposite particles as the final decomposition product.

Di-µ-hydroxido-bis-[hemiaqua-(N,N,N',N'-tetra-methyl-ethane-1,2-diamine)-copper(II)] bis-(tetra-fluoridoborate).

The title compound, [Cu(2)(OH)(2)(C(6)H(16)N(2))(2)(H(2)O)](BF(4))(2), consists of dinuclear centrosymmetric [Cu(2)(OH)(2)(tmen)(2)(H(2)O)](2+) complex cations (tmen = N,N,N',N'-tetra-methyl-ethane-1,2-diamine) and tetra-fluoridoborate anions. In the cation, the Cu(II) atom shows a slightly distorted square-pyramidal coordination geometry provided by a pair of µ-OH(-) anions and by the N atoms of a chelate tmen ligand in the basal plane. The apical position is statistically occupied by the O atom of a half-occupancy water mol-ecule. The F atoms of the anion are disordered over three sets of sites with occupancies of 0.598 (9):0.269 (6):0.134 (8). The crystal packing is governed by ionic forces as well as by O-H⋯F hydrogen bonds.

The chain structure of [Ni(C(4)H(2)O(4))(C(12)H(8)N(2))(H(2)O)](n) with different types of fumarate bridging.

Using modified solvothermal conditions (longer cooling time), beside previously characterized dark-green crystals of [Ni(C(4)H(2)O(4))(C(12)H(8)N(2))] (main product), a few light-green crystals of the polymeric title compound, catena-poly[[aqua-(1,10-phenanthroline-κ(2)N,N')nickel(II)]-µ-fumarato-κ(2)O:O'-[aqua-(1,10-phenanthroline-κ(2)N,N')nickel(II)]-µ-fumarato-κ(4)O,O':O'',O'''], [Ni(C(4)H(2)O(4))(C(12)H(8)N(2))(H(2)O)](n) were isolated. Its crystal structure is made up from zigzag chains, propagating in [001], in which the Ni(2+) ions are linked alternatively by µ(2)-fumarato and bis-chelating fumarato bridging ligands. The Ni(2+) ion is coordinated in a deformed octa-hedral geometry by one chelating 1,10-phenanthroline ligand, one aqua ligand in a cis position with regard to both N-donor atoms and by two different fumarato ligands, each residing with its central C=C bond on an inversion centre, occupying the remaining coordination sites in a fac fashion. The chains thus formed are linked by O-H⋯O hydrogen bonds and π-π inter-actions between the aromatic rings of the phenanthroline ligands with a shortest ring centroid separation of 3.4787 (10) Å.

catena-Poly[[[diaqua-(di-2-pyridylamine-κN,N')nickel(II)]-µ-fumarato-κO:O] tetra-hydrate].

In the crystal structure of the title compound, {[Ni(C(4)H(2)O(4))(C(10)H(9)N(3))(H(2)O)(2)]·4H(2)O}(n), zigzag chains are built up from cis-[Ni(dpya)(H(2)O)(2)](2+) cations (dpya is di-2-pyridylamine) linked by bis-monodentate coordinated bridging fumarate ligands. The Ni(II) atom is coordinated by one chelating dpya ligand, two aqua ligands in trans positions and two monodentate fumarate ligands in cis positions in the form of a deformed octa-hedron. The water mol-ecules, O atoms of the fumarate carboxyl-ate groups and the amine group of the dpya ligand are involved in an extended network of intra- and inter-molecular O-H⋯O hydrogen bonds. Moreover, π-π inter-actions between the pyridine rings of the dpya ligand contribute to the stability of the structure. Two of the five uncoordinated water molecules are half-occupied.

Redetermination of aqua-(dihydrogen ethyl-enediamine-tetra-acetato-κO,O',N,N',O'')nickel(II).

The crystal structure of the title compound, [Ni(C(10)H(14)N(2)O(8))(H(2)O)] or [Ni(H(2)edta)(H(2)O)] (H(4)edta is ethyl-ene-diamine-tetra-acetic acid), originally determined by Smith & Hoard [J. Am. Chem. Soc. (1959), 81, 556-561] has been redetermined to a significantly higher precision. The Ni(II) atom is coordinated in a distorted octa-hedral geometry by two N atoms and three O atoms from three carboxyl-ate groups of the H(2)edta(2-) ligand and by an O atom of a water mol-ecule. The complex mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds into layers perpendicular to [100].

Tris(1,2-diamino-ethane)-nickel(II) hexa-fluoridosilicate.

The ionic title complex, [Ni(C(2)H(8)N(2))(3)](SiF(6)), is built up of [Ni(en)(3)](2+) complex cations (en = 1,2-diamino-ethane) and hexa-fluoridosilicate anions. Single crystals of the title complex were isolated from an aqueous-ethano-lic Ni(2+)-en-SiF(6) (2-) system. The Ni(II) and Si atoms are each located on a special position with site symmetry 3.2. The Ni(II) atom coordination sphere is octa-hedrally deformed, being coordinated by three chelating diamine ligands with an Ni-N distance of 2.1233 (18) Å. The crystal packing of the respective ions corresponds to the structure type of the hexa-gonal form of BN. Beside ionic forces, the packing is governed by N-H⋯F hydrogen bonds, which lead to the formation of hydro-phobic channels running along the 6(3) screw axis. The structure was refined as an inversion twin [0.49 (3): 0.51 (3)].

Two different one-dimensional structural motifs in [catena-{Cu(tacn)}2Pd(CN)4]Br2.[catena-Cu(tacn)Pd(CN)4]2.H2O (tacn is 1,4,7-triazacyclononane).

The title compound, catena-poly[[bis[(triazacyclononane-kappa(3)N,N',N'')copper(II)]-di-mu-cyanido-kappa(4)N:C-palladate(II)-di-mu-cyanido-kappa(4)C:N] dibromide bis[[(triazacyclononane-kappa(3)N,N',N'')copper(II)]-mu-cyanido-kappa(2)N:C-[dicyanidopalladate(II)]-mu-cyanido-kappa(2)C:N] monohydrate], {[Cu(2)Pd(CN)(4)(C(6)H(15)N(3))(2)]Br(2).[Cu(2)Pd(2)(CN)(8)(C(6)H(15)N(3))(2)].H(2)O}(n), (I), was isolated from an aqueous solution containing tacn.3HBr (tacn is 1,4,7-triazacyclononane), Cu(2+) and tetracyanidopalladate(2-) anions. The crystal structure of (I) is essentially ionic and built up of 2,2-electroneutral chains, viz. [Cu(tacn)(NC)-Pd(CN)(2)-(CN)-], positively charged 2,4-ribbons exhibiting the composition {[Cu(tacn)(NC)(2)-Pd(CN)(2)-Cu(tacn)](2n+)}(n), bromide anions and one disordered water molecule of crystallization. The O atom of the water molecule occupies two unique crystallographic positions, one on a centre of symmetry, which is half occupied, and the other in a general position with one-quarter occupancy. One of the tacn ligands also exhibits disorder. The formation of two different types of one-dimensional structural motif within the same structure is a unique feature of this compound.

Bis(di-2-pyridylamine-kappa2N2,N2')(nitrato-kappa2O,O')nickel(II) nitrate.

In the ionic title compound, [Ni(NO(3))(C(10)H(9)N(3))(2)]NO(3), the central Ni(II) atom exhibits cis-NiN(4)O(2) octahedral coordination with three chelating ligands, viz. one nitrate anion and two di-2-pyridylamine (dpya) molecules. A second nitrate group acts as a counter-ion. The complex cations and the nitrate anions are also linked by N-H...O hydrogen bonds. The compound was prepared in two different reproducible ways: direct synthesis from Ni(NO(3))(2) and dpya yielded systematically twinned crystals (the twinning law is discussed), while single crystals were obtained unexpectedly from the Ni(NO(3))(2)/dpya/maleic acid/NaOH system.

Tris(propane-1,2-diamine-κN,N')nickel(II) tetra-cyanidonickelate(II).

The title compound, [Ni(C(3)H(10)N(2))(3)][Ni(CN)(4)], is built up of [Ni(pn)(3)](2+) cations (pn is 1,2-diamino-propane) and [Ni(CN)(4)](2-) anions. Both Ni(II) atoms in the cation and the anion lie on a mirror plane. The respective ions inter-act through Coulombic forces and through a complex network of hydrogen bonds. Extended disorder associated with the cation has been resolved. The occupancies of the respective disordered positions are 0.4:0.4:0.2.

Bis(2,2'-bipyridine-κN,N')(maleato-κO,O)nickel(II) 7.34-hydrate.

The title compound, [Ni(C(4)H(2)O(4))(C(10)H(8)N(2))(2)]·7.34H(2)O, was obtained by crystallization from an aqueous ethano-lic reaction mixture containing nickel(II) acetate, maleic acid, bipyridine, sodium hydroxide and ammonia. The asymmetric unit contains one independent complex mol-ecule and 7.34 water mol-ecules occupying eight crystallographically independent positions. Two of these water molecules are disordered. The nickel(II) atom is coordinated in a distorted octa-hedral geometry by two O atoms from one carboxyl-ate group of the maleato ligand and by four N atoms from two 2,2'-bipyridine (bipy) ligands. The water mol-ecules, along with the O atoms of the uncoordinated carboxyl-ate group, form an extended hydro-philic three-dimensional hydrogen-bonded system with large cavities in which the hydro-phobic bipy ligands are located. One H atom of the maleate ligand is involved in a weak hydrogen bond of the C-H⋯O type. Stacking inter-actions between the pyridyl rings of the bipy ligands [centroid-centroid distance = 3.549 (15) Å] lead to the formation of pairs of complex mol-ecules.

Ammonium bis(tetraethylammonium) hexacyanidoferrate(III) trihydrate.

In the structure of the title salt, (NH(4))(C(8)H(20)N)(2)[Fe(CN)(6)].3H2O, the O atom of one of the water molecules shares its crystallographic site with the N atom of the ammonium cation in a 1:1 ratio. The second O atom from the two crystallographically independent water molecules is disordered over two positions separated by 0.551 (1) A. The water molecules and ammonium cations form tetrameric hydrogen-bonded units that, along with the complex anion, form the hydrophilic part of the structure. The hydrophobic part of the structure, represented by the tetraethylammonium cation, is located in cube-like cavities of the hydrophilic framework.