Bond Valence Sum Research Articles

Pyrrolidinecarbodithioate as a planarity chuck in the search for cis-platin analogues of nickel: Spectral, single crystal X-ray structural, BVS, and CSM analysis of some planar nickel(II) mixed ligand complexes

[Ni(pyrdtc)(PPh3)(NCS)] (1), [Ni(pyrdtc)(4-MP)(NCS)] (2), [Ni(pyrdtc)(PPh3)(CN)]·H2O (3), [Ni(pyrdtc)(PPh3)2]ClO4 (4), and [Ni(pyrdtc)(P͡P)]BPh4·2H2O (5) [where pyrdtc: Pyrrolidine carbodithioate/S͡S, PPh3: Triphenylphosphine, 4-MP: Tri(4-methylphenyl)phosphine, dppe/P͡P: 1,2-Bis(diphenylphosphino)ethane] have been prepared from the parent bis-dithiocarbamate, [Ni(pyrdtc)]2 (6). The prepared compounds were characterized by electronic, IR, 1H, 13C, and 31P NMR spectra. In the IR spectra of the compounds, thioureide bands are observed at higher wavenumbers for the mixed ligand complexes 1-5 (1528-1540 cm-1) than the parent compound (1490 cm-1). Cyclic voltammetry showed an increasing order of reduction potentials: 5 << 1 ~ 2 < 3 < 4 << [Ni(pyrdtc)2] indicating an alleviation of electron density on nickel in the mixed complexes compared to the parent compound. Single crystal X-ray structure of the complexes displayed planar geometry around nickel which is in keeping with their diamagnetism. Bond Valence Sums calculated with the corrected Rij indicated the divalent nature of nickel with predominant covalent interactions. Continuous shape measure analysis of the mixed ligand chromophores stipulates a planar square environment around central nickel atom and deviation to tetrahedral or trigonal bipyramidal variants are absolutely negated. In this study, CSM analysis of cis-platin, a clinical anti-cancer agent, showed a comparable shape measure as those of the mixed ligand complexes 1-5. Hence, pyrrolidinecarbodithioate acts as a ‘chuck’ in compounds 1-5 to stabilize the planar square shape of the nickel chromophores and provides a suitable template to synthesize analogues of cis-platin.

Formation of polynuclear iron(III) complexes of N-(2-pyridylmethyl)iminodipropanol depending on pseudohalide ions: synthesis, crystal structure, and magnetic properties

Five polynuclear iron(III) complexes, [(pmidp)Fe(NCSe)]2 (1), [(pmidp)Fe(NCBH3)]2 (2), [(Hpmidp/pmidp)Fe3(CH3O)2(NCS)4]∙H2O (3), [(pmidp)2Fe6(CH3O)4(N3)4(CH3COO)2O2] (4), and [(pmidp)2Fe6(CH3O)4(NCO)4(CH3COO)2O2]∙2MeOH (5) were isolated through the reactions of N-(2-pyridylmethyl)iminodipropanol (H2pmidp) and iron(III) ions with different pseudohalide ions. The complexes were studied via X-ray crystal diffraction, Mössbauer spectra, and magnetochemistry. The molecular structures of 1 and 2 were formed as the {Fe2(µ2-Opropoxo)2}2+ cores with pmidp2− and NCSe−/NCBH3−. The structure of 3 was formed as a {Fe3(µ2-OCH3)2(µ2-Opropoxo)4}5+ core with Hpmidp−/pmidp2− and NCS−. The structures of 4 and 5 were formed as {Fe6(µ4-O)2(µ2-OCH3)2(η2-OAc)2(µ2-Opropoxo)4} cores with pmidp2− and NCO−/N3−. Structural analyses revealed that the formation of various multinuclear iron(III) moieties depends on the auxiliary ligands. The oxidation states of all the complexes were confirmed as + 3 using the bond valence sum (BVS) calculations and Mössbauer spectral data. The susceptibility data for 1–5 fitted using each spin coupling (J) model indicated that 1–3 showed antiferromagnetic exchange interactions, and 4 and 5 showed the ferromagnetic and antiferromagnetic couplings, simultaneously.

Understanding of the bond covalency nature with ionic electronegativity in perovskite cuprates La2CuMO6-x (M = Ti, Mn, Ru)

A bond valence sums (BVS) modified ionic electronegativity (EN) scale was suggested for better accommodating the double perovskite La2CuMO6-x (M ​= ​Ti, Mn, Ru) with mixed bonding nature. Both the M ​− ​O bond covalency fraction (f) and the cooperative B-site sublattice distortion are highlighted to connect structure and physical properties. Particularly, the Ti-based compound hosts the largest M/O ionic EN difference and hence yields the smallest f value while the Ru-based analogue exhibits the opposite result. As the consequence, robust spin disordering accompany with poor dc conductivity is convinced in the Ti-based sample owing to its featuring B-site ionic arrangement and profound suppression of 3d(Ti)-2p(O) orbital hybridization. For the Ru-based sample, strong ferromagnetic spin frustration and low charge carrier hopping potential might be essentially ascribed to its large f value through enhancing orbital degeneracy between 4d(eg)-2p σ and 4d(t2g)-2p π bonding states. The Mn-based sample with the moderate f value exhibits the similar magnetic and electric behaviors as those of Ru-based sample. Both the d(M)-p(O) orbital hybridization and the M ​− ​O bond covalency could be tuned by rationally selecting the M cation with proper ionic EN value. This work provides a deep understanding of the bond covalency nature in perovskite cuprates and might help to develop novel electronic functional materials.

High‐pressure synthesis, crystal structure, and magnetic property of LaCo6O11

AbstractA novel cobalt oxide LaCo6O11 has been synthesized under high pressure of 8 GPa, and its crystal structure and magnetic property have been investigated. Rietveld analysis using synchrotron X‐ray powder diffraction data demonstrates that LaCo6O11 crystallizes in the magnetoplumbite‐derived structure as well as A2+Co6O11 (A = Ca, Sr, Ba). Bond valence sum (BVS) calculation exhibits a substantial decrease in BVS of octahedral Co sites with itinerant electrons, whereas BVS at trigonal bipyramidal Co site with localized electrons is unchanged, indicating that the doped electrons are predominantly injected into the Co sites with electric conductivity. Magnetization measurement shows that the magnetic ground state of LaCo6O11 is similar to the antiferromagnetic‐like one in CaCo6O11. However, the absence of a field‐induced ferrimagnetic transition in LaCo6O11 indicates the robustness of the antiferromagnetic‐like ground state. The difference in the magnetic state under the external magnetic field between LaCo6O11 and CaCo6O11 is attributed to the suppression of the ferromagnetic RKKY interaction because of the reduction in hole carrier density by La3+ substitution for Ca2+.

Effects of Bi doping on structural and magnetic properties of cobalt ferrite perovskite oxide LaCo0.5Fe0.5O3

Literature reports on magnetic transition of LaFe0.5Co0.5O3 are highly ambiguous. The present study is an endeavour to address that particular issue of this ferrite perovskite. Here we report the low temperature sol-gel synthesis of pure and Bi-doped La1-xBixFe0.5Co0.5O3 (x = 0, 0.1 & 0.2) perovskites. All the samples were characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray (EDX) analysis and magnetization studies. LaFe0.5Co0.5O3 crystallizes in a single phase rhombohedral (R-3c) structure. Substitution of Bi at the A-site results in structural transition. La0.9Bi0.1Fe0.5Co0.5O3 exhibits mixed rhombohedra (R-3c) and orthorhombic (Pbnm) phases, whereas La0.8Bi0.2Fe0.5Co0.5O3 is single phase orthorhombic (Pbnm). Favourable grain growth and good crystallinity observed in Bi doped samples are possibly due to the low melting temperature of Bi containing La1-xBixFe0.5Co0.5O3. EDX analysis confirms the chemical homogeneity of the samples. XPS studies and bond valence sum calculations confirm the nominal cationic oxidation states of the ions. Magnetization measurements reveal the weak ferromagnetic nature of La1-xBixFe0.5Co0.5O3 (x = 0, 0.1 & 0.2) which is associated to the canted antiferromagnetic structure. The magnetically active subsystem of Fe3+ ions are responsible for weak ferromagnetism which is explained by the antisymmetric Dzyaloshinskii–Moriya interaction, whereas the Co3+ ions remain predominantly in the low spin state. The increase in magnetic transition and the lower magnetic moment with an increase in Bi content can be related to the weakening of Dzyaloshinskii–Moriya interaction due to structural modification and local lattice distortion associated to the stereochemically active 6s2 lone pair electrons of the Bi3+ ions. Our results confirm the high structure sensitivity of magnetic properties of cobalt ferrite perovskite.

REGULARITIES OF PHYSICO-CHEMICAL INTERACTION IN THE QUASIBINARY SYSTEMS BASED ON THE TERNARY HALIDES Rb3(Cs3)Sb2(Bi2)Br9(I9) AND K2(Rb2,Cs2,Tl2)TeBr6(I6): EXPLANATION WITHIN THE FRAMEWORK OF THE BOND VALENCE MODEL

The work is the first attempt to employ the bond valence model (BVM) in the explanation and interpretation of the phase diagrams observed for the quasibinary systems based on the ternary halides Rb3(Cs3)Sb2(Bi2)Br9(I9) (A3B2X9) and K2(Rb2,Cs2,Tl2)TeBr6(I6) (A2BX6) belonging to the structural family of perovskite. The most characteristic features of the phase diagrams of such systems are (a) a monotonic increase in the melting and crystallization temperatures when the smaller A atom is replaced by a larger chemical analogue; (b) a gradual decrease in the melting and crystallization temperatures when the bromine atoms are replaced by iodine atoms, reaching the temperature minimum at a molar ratio of ~1 : 1, and then an increase of the temperatures to the pure iodine component of the system. With the isostructurality of the starting components, in case (a) a continuous series of solid solutions (CSSS) of substitution is formed, without a temperature minimum; if the starting components belong to different structural types, then a peritectic interaction with the wide concentration limits of solid solutions is observed. Under the same conditions concerning the isostructurality/non-isostructurality of starting components, in case (b), correspondingly, either a CSSS of substitution with a temperature minimum is formed or eutectic interaction with the wide concentration limits of solid solutions is observed.
 Within the framework of the BVM, in case (a) a monotonic increase of the melting and crystallization temperatures when replacing a smaller atom A with a larger analogue can be interpreted as a consequence of reducing the deficit of the bond valence sum (BVS) for cations A, resulting in the stabilization of the structure as a whole. In case (b), partial replacement of one halogen ion by a halogen ions of another sort leads either to a deficit (if a larger anion is replaced by a smaller one) or to an excess (if a smaller anion is replaced by a larger one) of the BVS values for the cations A and for the anion that replaced the main halogen sort. An increase in the excess or deficit of the BVS values destabilizes the structure of ternary halides, reducing the melting and crystallization temperatures; the maximum destabilization is achieved at a ~1 : 1 molar ratio of the components, which is expressed in reaching the characteristic temperature minimum of the respective systems.
 The approach described in the work can expectedly be employed in explanation and interpretation of another phase diagrams based on the structures featuring the closest packing formed by alkaline metals and halogens.
 Keywords: ternary halides; crystal structures; phase diagrams; bond valence model.

Co3Gd4 Cage as Magnetic Refrigerant and Co3Dy3 Cage Showing Slow Relaxation of Magnetisation.

Two structurally dissimilar 3d-4f cages having the formulae [(CoIII)3Gd4(μ3-OH)2(CO3) (O2CtBu)11(teaH)3]·5H2O (1) and [(CoIII)3Dy3(μ3-OH)4(O2CtBu)6(teaH)3]·(NO3)2·H2O (2) have been isolated under similar reaction conditions and stoichiometry of the reactants. The most important factor for structural diversity seems to be the incorporation of one μ3-carbonate anion in 1 and not in 2. Co atoms are in a +3 oxidation state in both complexes, as shown by the Bond Valence Sum (BVS) calculations and bond lengths, and as further supported by magnetic measurements. Co3Gd4 displays a significant magnetocaloric effect (−∆Sm = 25.67 J kg−1 K−1), and Co3Dy3 shows a single molecule magnet (SMM) behavior.

Electrochemical-driven water reduction and oxidation catalyzed by an iron(III) complex supported by a N2O2 ligand

One new electrocatalyst for both water reduction and oxidation, based on an iron(III) complex, FeIII(TAMP)Cl, is formed by the reaction of anhydrous FeCl3 with thiobis(2,1-phenylene)-bis(azanylyidene)-bis(methanylylidene)-bis-phenol (H2TAMP). Its structure has been determined by X-ray diffraction. A Bond-Valence Sum (BVS) model calculation was performed to assign the oxidation state of the iron center in FeIII(TAMP)Cl. FeIII(TAMP)Cl can electrocatalyze hydrogen evolution from a neutral electrolyte solution (pH 7.0) with a turnover frequency (TOF) of 2.43 mol of hydrogen per mole of catalyst per second (mol (mol cat)−1s−1) at an overpotential (OP) of 837 mV. Water oxidation occurs at an overpotential of 791 mV to give O2 with a TOF of ∼124.06 mol O2 (mol cat)−1s−1. Sustained proton reduction catalysis occurs at glassy carbon to afford H2 over a 5 h electrolysis period with 92% Faradaic yield and no observable decomposition of FeIII(TAMP)Cl. We hope these findings can afford a new method for the design of electrocatalysts for both water reduction and oxidation.

Giant Ln 30 -Cluster-Embedded Polyoxotungstate Nanoclusters with Exceptional Proton-Conducting and Luminescent Properties

Giant Ln ₃₀ -Cluster-Embedded Polyoxotungstate Nanoclusters with Exceptional Proton-Conducting and Luminescent Properties

Synthesis, characterization, and magnetic / electrochemical properties of Wells-Dawson polyoxometalate containing Ni (II) counter-ion

The monomeric Ni(II) containing Wells-Dawson polyoxometalate (POM) complex K2Rb6Ni0.33[P2W18O62]Cl2∼15·3H2O (K2Rb6–1) was synthesized, for the first time, by the reaction of [Ni2(µ-OH2)(O2CCMe3)4(HO2CCMe3)4] and K6[P2W18O62]. 19H2O in an aqueous medium. The compound was characterized by elemental analysis, FTIR, TGA, and single-crystal XRD (trigonal, space group R3¯m, cell length a = 37.3660(4), b = 37.3660(4), c = 12.8340(2) Å, α = 90, β = 90, γ = 120°, V = 15,518.4(3), Z = 9) techniques. The oxidation state of Ni(II) was calculated through bond valence sum (BVS) calculations. The electrochemical study indicated the super capacitance behavior of POM K2Rb6–1, and its magnetic susceptibility study showed magnetization with a temperature range of 5 K-300 K.

Crystal structure, charge-distribution and bond-valence-sum investigations of a new layered phosphate SrFe(HPO4)(PO4)

The new compound SrFe(HPO4)(PO4), has been prepared using mild hydrothermal conditions under autogenous pressure and characterized by single-crystal X-ray diffraction. The crystal structure of this compound crystallizes in the triclinic system space group P-1 with Z = 2 and the cell parameters a = 5.1766 (2) Å, b = 7.1346 (2) Å, c = 8.5695 (3) Å, α = 91.093 (2)°, β = 91.029 (2)°, γ = 90.313 (2)°, V = 316.36 (2) Å3. The structure exhibits a layered framework which could be described as a stacking [Fe(HPO4)(PO4)]∞2− layers of corner sharing FeO6 octahedra and the bridging PO4/PO3(OH) tetrahedra along the [010] direction. Such hetero-polyhedral arrangement gives a rise to a strong O—H···O hydrogen bonds into the intra-layers region. Adjacent layers are held to each other through the Sr2+ cations located in the resulting corrugated interstitial space. The validation of the proposed structural model is supported by means bond-valence-sum (BVS) and charge-distribution (CHARDI) methods.

Effect of Bond Valence Sum on the Structural Modeling of Lead Borate Glass

Effect of Bond Valence Sum on the Structural Modeling of Lead Borate Glass

Uranium oxide hydrate frameworks with Er(III) or Y(III) ions: revealing structural insights leading to the low symmetry.

Two new mixed-valence uranium oxide hydrate frameworks (UOFs), incorporating either Er3+ or Y3+ ions, were successfully synthesised under hydrothermal conditions and characterised with single-crystal X-ray diffraction and a variety of other structural and spectroscopic techniques. Both frameworks are isostructural and crystallise in the triclinic P1̄ space group, consisting of β-U3O8 type layers pillared by additional uranyl centres, with the Er3+/Y3+ ions lying in the channels of the framework. SEM-EDS analysis found that both materials existed in plate-like morphologies, with a U:Er/Y ratio of 5.5. Bond valence sum analysis revealed the possible existence of pentavalent uranium centres, which was confirmed with diffuse reflectance spectroscopy. Being the first reported UOFs in this space group, this work highlights the complex and flexible nature of these materials, and the broader uranium oxide hydrate systems which exist in the surrounds of spent nuclear fuel disposal in the underground repository.

K6(IO6H4)(HI2O6)(HIO3)2(IO3)4·2H2O: A Case of Iodate with Coexisting [I5+O3] and [I7+O6] Units.

A new alkali-metal iodate, K6(IO6H4)(HI2O6)(HIO3)2(IO3)4·2H2O (KIOH), was successfully grown at room temperature by a slow evaporation method. To our knowledge, the title compound is the first alkali-metal iodate containing isolated [I5+O3] and [I7+O6] units in one structure. Both the bond valence sum and X-ray photoelectron spectroscopy confirmed this phenomenon, which is consistent with the single-crystal data. Also, the theoretical calculation results showed that the title compound is a potential birefringent material. What is more, the low-cost growth of centimeter-sized crystals for the title compound greatly enriches the structural chemistry of the iodate system.

A Structural Investigation of T’-Pr2-xCexCuO4 nanocrystals with x = 0.13

This report is briefly investigating the structural defect information of T’-Pr 2- x Ce x CuO 4 (T’-PCCO) nanocrystals with x = 0.13 at three different calcination temperatures. The as-synthesized powder of Pr 2- x Ce x CuO 4 (PCCO) nanocrystals with x = 0.13 were synthesized by using the chemically dissolved method within three different calcination temperatures, namely 900 o C, 950 o C, and 1000 o C for 15 h in air. X-ray diffraction (XRD) technique is used to characterize the phase, structural, and crystalline defect information on the nanocrystal powder. It is found that all the indexed peaks are confirmed as PCCO phase with space group of I4/mmm and a minor impurity of Fm-3m space group. The lattice parameters are confirmed to be fluctuated signifying the stability of the Coulomb force at those temperatures. The post-Rietveld analysis using Bond Valance Sum (BVS) calculation shows the Ce-dependent of T’-PCCO nanocrystals while the Fourier difference suggests that the created crystalline defect as a part of the tetravalent doping effect which binds stronger apical oxygen. Moreover, at Pr- and Cu-site, the scattering distribution are fluctuating with the stable structure at 1000 o C. This initial structural information is worth complementing the fundamental feature for understanding the T’-type cuprates.

Experimental and theoretical investigations on structural-function relationship of new iron (III) complex with 2-(Ammoniomethyl)pyridinium cation as ligand: A promising material for green solar cells

Crystals of (H2AMP)2[FeIIIBr4]Br3, where AMP refers to the 2-(Ammoniomethyl)pyridinium ligand, have been successfully synthesized through redox chemistry and analyzed using X-ray crystallography. The new complex crystallizes as red needles in the monoclinic space group, P21/c, with eight formula weights in a unit cell of dimensions: a = 12.358 (13), b = 28.572 (3), c = 13.544 (14) Å and β=92.009(5) °. Analysis of absorption and reflectance data through the visible and near-infrared provide insight into the optical properties of the material. The structural data and the BVS (Bond Valence Sum) calculations are in agreement with the iron (III) oxidation. In this work, the experimental and theoretical study on molecular structure and vibrational spectral analysis of the new product has been reported. Theoretical calculations were performed by using density functional theory (DFT) at the B3LYP/LAN2DZ basis set levels. The electronic parameters such as frontier molecular orbital, electrostatic potential and HOMO-LUMO energy were calculated. Also, NLO were studied with the same level of DFT. The theoretical values show good agreement with experimental values. In addition, (H2AMP)2[FeIIIBr4]Br3 reveals broad absorption across the visible spectrum and an optical bandgap of 1.06 eV. Then the obtained material can be a promising eco-friendly light absorber in solar cell application. Finally, the thermal behavior of this material has been performed by TGA/DTA. In addition, two phase transitions at T1 = 108 °C and T2 = 170 °C were evidenced by DSC measurements.

Effects of rare-earth doping and reduction processes in LiCaPO4 compound: A computer simulation study

We perform a computational study of rare earth (RE) doping of the LiCaPO4 structure using an atomistic simulation based on lattice energy minimisation. Particular attention is given to the effects of RE doping on the structure of LiCaPO4. It is found that RE3+ and RE2+ dopant ions have an energetic preference to be incorporated at the Ca2+ host site. Our simulations show that for the incorporation of the RE3+ ion, charge compensation by LiCa, antisite defects is more likely to occur. In addition, the bond valence sum (BVS) is obtained for the RE3+-O2- pair. To investigate Eu reduction doping mechanisms, three reduction mechanisms (open atmosphere, CO and a H2 reducing atmosphere) are considered. An H2 reducing atmosphere was found to be the most effective agent for Eu reduction. Our results reveal the possibility of the co-existence of both Eu3+ and Eu2+ ions in the host. In fact, a specific study of the lattice deformation by various types of defect mechanisms can improve the effective rate performance of LiCaPO4 for luminescent applications.

NaFe2PO4(MoO4)2: A Promising NASICON-Type Electrode Material for Sodium-Ion Batteries.

Searching for polyanionic electrode materials with high Na+ and electronic conductivity is pivotal to realize high-performance sodium-ion batteries. Here, we report a novel polyanionic-based NASICON-type compound, NaFe2PO4(MoO4)2 (NFPM), that does not crystallize in the common space group R-3c or C2/c but in the rare P2/c. The studies on bond valence sum maps show that NFPM has high Na+ conductivity because the large volumes of MoO4 groups make the interstitial channels wider, thus making the energy barrier of Na+ diffusion decrease along these channels. Density functional theory calculations demonstrate that NFPM has high electronic conductivity because the contribution of Mo 4d orbitals on the formation of the bottom of the conduction band makes the connected MoO4 groups take part in electron transport. Electrochemical tests exhibit that NFPM can deliver a capacity of ∼80 mAh g-1 with good reversible cyclability utilizing the Fe3+/Fe2+ redox couple. In situ X-ray diffraction measurements indicate that NFPM undergoes one-phase reaction mechanism in the process of charge and discharge.

Li-diffusion pathways in [formula omitted] and [formula omitted] MXenes using the Bond Valence Sum model

Two-dimensional materials such as MXenes are being actively considered by the community for energy storage applications. Here, we employ Density Functional Theory (DFT) to model O and S terminated Zr2C MXenes. We find that the most energetically favourable positions for the termination atoms to sit are on top of the second-layer Zr atoms, in agreement with previous studies. Finally, arbitrarily placing a Li-ion on the surface of the MXenes, we apply the Bond Valence Sum (BVS) model to calculate Bond Valence Site Energies (BVSE). We show that BVS is a good substitute for DFT particularly for diffusion pathways, as it yields much faster results and with good accuracy, with the added advantage of not needing exact positions for the atoms. BVS can, therefore, be used as a quick filter when searching for low migration barriers in MXenes and two-dimensional materials.

Fluorite-like hydrolyzed hexanuclear coordination clusters of Zr(IV) and Hf(IV) with syn-syn bridging N,N,N-trimethylglycine in soft crystal structures exhibiting cold-crystallization

Tetravalent metal ions are hydrolyzed under presence of N,N,N-trimethylglycine hydrochloride (betaine hydrochloride, [Hbet]Cl) in aqueous solutions to afford [M6(μ3-O)4(μ3-OH)4(μ-bet)8(κ-bet)4(H2O)4]12+ (M4+ = Zr4+ (1), Hf4+ (2)) as hydrated perchlorate salts. These compounds were characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. As a result, we have found that fluorite-like [M6O8] coordination clusters are formed through octahedral arrangement of six M4+ linked by μ3-O atoms. Additionally, each pair of neighboring M4+ are connected by the μ-bet ligand through a syn-syn bridging coordination of its carboxylate moiety. This interaction seems to prevent further growth of the fluorite structure leading to formation of MO2. It was difficult to directly distinguish each μ3-O atom to be μ3-OH− or μ3-O2− due to its strongly anisotropic thermal displacement in the obtained structures. Bond valence sum analysis suggested that four μ3-OH− and four μ3-O2− are alternately arranged in the [M6O8] core motifs. Indeed, such a symmetric structure of [M6(μ3-O)4(μ3-OH)4] was confirmed in another phase of 1 at 296 K, where 1 transforms to a monoclinic structure (1′). The number of ClO4− counteranions found in the structure determination is not enough to compensate + 12 charge of [M6(μ3-O)4(μ3-OH)4(μ-bet)8(κ-bet)4(H2O)4]12+ in any unit cells of 1, 1′ and 2. Instead, large solvent/ion accessible voids have been actually observed in their crystal structures, indicating that the missing ClO4− are located therein and are significantly disordered to make them invisible in the crystallography. DSC analysis revealed that ClO4− and H2O/H3O+ in the crystal lattice of 1 undergo unique structure relaxation and rearrangements pronounced by cold-crystallization to induce the phase transition from 1 to 1′ with elevating temperature.