Thermogravimetric and infrared studies of tetrameric zirconium(IV) compounds derived from oxozirconium(IV) chloride and imidazole,morpholine and their derivatives

Oxozirconium chloride reacts with imidazole, morpholine and their derivatives in acetone medium in the presence of triethylorthoformate to form white amorphous compounds with a high melting point. IR and thermogravimetric measurements as well as analytical data indicate their polymeric formulation in the solid state where the structure is derived from the basic tetrameric dodecahedral structure of the parent ZrOCl₂ ·8H₂O formulated as [Zr₄(OH)₈(H₂O)₁₆Cl₈. The unidentate imidazole or morpholine ligands appear to replace some of the coordinated H₂O molecules and deprotonate some other H₂O molecules forming compounds of the type [Zr₄(OH)₁₂(H₂O)_12−nL_n]Cl₄ where n = 1 for L = 1-MeIm, 1-EtIm, 1-ViIm, 2-iPrIm, 2-PhIm; n = 2 for L = Im, 2-MeIm, 4-MeMorph and n = 4 for L = Morph. Thermogravimetric studies indicate the stepwise loss of water molecules and the ligands forming complex intermediates with increase in temperature. The stoichiometry of decomposition products is calculated. Based on initial decomposition temperature, an order of thermal stability for the complexes is proposed.     

Complexes based on the anionic octahedral rhenium chalcogenide clusters and [M(En)<Subscript>2</Subscript>]<Superscript>2+</Superscript> (M = Ni,Cu) cations

The compounds [Ni(H₂O)₂(En)₂][{Ni(En)₂}Re₆S₈(OH)₆] · 7H₂O (I), [{Cu(En)₂}Re₆S₈(H₂O)₂(OH)₄] · 4H₂O (II), and [Ni(H₂O)₂(En)₂]_0.5[Re₆Se₈(H₂O)₃(OH)₃] · 10H₂O (III) were synthesized by layering aqueous solutions of Ni(En)₂Cl₂ or Cu(En)₂Cl₂ (En is ethylenediamine) onto aqueous solutions of the potassium salts of the corresponding octahedral chalcohydroxo rhenium cluster complexes [Re₆Q₈(OH)₆]⁴⁻ (Q = S, Se). The structure of the obtained compounds was determined by X-ray diffraction analysis.     

Novel platinum(II) and (IV) complexes of naphthaldimine schiff bases

Naphthaldimines containing N₂O₂ donor centers react with platinum(II) and (IV) chlorides to give two types of complexes depending on the valence of the platinum ion. For [Pt(II)], the ligand is neutral, [(H₂L¹)PtCl₂]·3H₂O (1) and [(H₂L³)₂Pt₂Cl₄]·5H₂O (3), or monobasic [(HL²)₂Pt₂Cl₂]·2H₂O (2) and [(HL⁴)₂Pt]·2H₂O (4). These complexes are all diamagnetic having square-planar geometry. For [Pt(IV)], the ligand is dibasic, [(L¹)Pt₂Cl₄(OH)₂]·2H₂O (5), [(L²)Pt₃Cl₁₀]·3H₂O (6), [(L³)Pt₂Cl₄(OH)₂]·C₂H₅OH (7) and [(L⁴)Pt₂Cl₆]·H₂O (8). The Pt(IV) complexes are diamagnetic and exhibit octahedral configuration around the platinum ion. The complexes were characterized by elemental analysis, UV-Vis and IR spectra, electrical conductivity and thermal analyses (DTA and TGA). The molar conductances in DMF solutions indicate that the complexes are non-ionic. The complexes were tested for their catalytic activities towards cathodic reduction of oxygen.     

Structures of cerium manganese pivalates

The Ce,Mn mixed-metal polynuclear compounds [Ce ₃Mn₆(O)₅(OH)₃Piv₁₂Cl₂(THF)₃]·2THF, [Ce₃Mn₈(O)₈Piv₁₆Cl₂(HPiv)₂]·C₇H₁₆, [Ce₁₀Mn₄(O)₆(OH)₁₂Piv₁₆Cl₂(THF)₂]·2THF·2H₂O, [CeMn₁₁Cl₃(O)₈Piv₁₅(H₂O)]·CH₂Cl₂, and [CeMn₈(O)₈Piv₁₂(HPiv)₂(THF)₂] were prepared and structurally characterized. The possibility of synthesizing p,d,f-heterospin complexes by replacing coordinated THF molecules by nitroxide molecules was exemplified by the reaction of [Ce₃Mn₆(O)₅(OH)₃Piv₁₂Cl₂(THF)₃]·2THF with nitronyl nitroxides (NIT-R is 2-R-4,4,5,5-tetramethyl-24midazoline-l-oxyl 3-oxide; R is Me or 4-Py). The X-ray diffraction study of these complexes showed that [Ce₃Mn₆(O)₅(OH)₃Piv₁₂Cl₂(HPiv)(NIT-Me)₂] and [CeMn₈(O)₈Piv₁₂(NIT4-Py) ₄] · 2C₆H₁₄ have a molecular structure and [Ce₃Mn₆(O)₅(OH)₃-Piv₁₂Cl₂(NIT-Me)(H₂O)] is an infinite chain.     

Encapsulation of Chloride-water cluster anion [Cl6(H2O)8]6- in a cage structure based [Cu(DMAP)4]2+ aggregation

A well chloride?water cluster [Cl₆(H₂O)₈]^6? in the complex [Cu₃(DMAP)₁₂Cl₆?8H₂O] (DMAP = N,N’-dimethyl p-aminopyridine) has been investigated structurally in the solid state. The chloride-water cluster [Cl₆(H₂O)₈]^6? is stabilized and orderly arranged by hydrogen bonds which display high symmetry. Six hosts [Cu(DMAP)₄]²⁺ cationic form a cage-like aggregation, and chloride-water [Cl₆(H₂O)₈]^6? cluster located in the cage. Cl^? anion play an important role to connect cubane-like (H₂O)₈ water cluster forming [Cl₆(H₂O)₈]^6? cluster, and on the other hand, to connect cage-like [Cu(DMAP)₄]²⁺ cationic aggregation by means of ionic electrostatic interaction and long-range coordinate bond interaction. The formation of such a cluster anion may be available for insight into the nature of hydration of chloride in H₂O.     

Stabilization of tautomeric forms P(OH)3 and HP(OH)2 and their derivatives by coordination to palladium and nickel atoms in heterometallic clusters with the Mo3MQ44+ core (M = Ni, Pd; Q = S, Se)

The cluster aqua complexes [Mo₃(MCl)Q₄(H₂O)₉]³⁺ (M = Pd or Ni) in hydrochloric acid solutions induce isomerization of the hydrophosphoryl compounds (HO)₂P(O)H, (HO)P(O)H₂, PhP(O)(OH)H, and Ph₂P(O)H into the hydroxo tautomers P(OH)₃, HP(OH)₂, PhP(OH)₂, and Ph₂P(OH), which are stabilized by coordination of the phosphorus atom to the Pd or Ni atoms. The reactions were studied by ³¹P NMR and UV-Vis spectroscopy. The kinetics of the reactions of phosphorous acid with [Mo₃(PdCl)Q₄(H₂O)₉]³⁺ was investigated by spectrophotometry. The [Mo₃(Pd(PhP(OH)₂))S₄(H₂O)₂Cl₇]³⁻ complex was isolated as a supramolecular adduct with cucurbit [8]uril, and the [Mo₃(Ni(P(OH)₃))S₄(H₂O)₈Cl]³⁺ complex was isolated as an adduct with cucurbit [6]uril. The structures of both compounds were established by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 606–613, March, 2005.     

Synthesis,Crystal Structure and Magnetic Behaviour of the new Tetrameric Gadolinium Carboxylate [Gd4(OH)4(CF3COO)8(H2O)4] · 2.5 H2O

The novel tetrameric gadolinium(III) compound [Gd₄(OH)₄(CF₃COO)₈(H₂O)₄] · 2.5 H₂O was synthesized and structurally characterized by X‐ray crystallography. The Gd³⁺ ions are bridged by hydroxide ions and carboxylate groups to tetramers with Gd³⁺‐Gd³⁺ distances between 384.2(2) and 388.1(2) pm. The compound crystallizes in the monoclinic space group C2/c (Z = 4). The magnetic behaviour of [Gd₄(OH)₄(CF₃COO)₈(H₂O)₄] · 2.5 H₂O was investigated in the temperature range of 2 to 300 K. The magnetic data of this compound indicate antiferromagnetic interactions (J_ex = ?0.0197 cm^?1).     

The Cocrystallization of the Cubic [Ta6Br12(H2O)6][CuBr2X2]·10H2O and Triclinic [Ta6Br12(H2O)6]X2·trans‐[Ta6Br12(OH)4(H2O)2]·18H2O (X = Cl,Br, NO3) Phases with the Coexistence of [Ta6Br12]2+ and [Ta6Br12]4+ in the Latter

Cubic [Ta₆Br₁₂(H₂O)₆][CuBr₂X₂]·10H₂O and triclinic [Ta₆Br₁₂(H₂O)₆]X₂·trans‐[Ta₆Br₁₂(OH)₄(H₂O)₂]·18H₂O (X = Cl, Br, NO₃) cocrystallize in aqueous solutions of [Ta₆Br₁₂]²⁺ in the presence of Cu²⁺ ions. The crystal structures of [Ta₆Br₁₂(H₂O)₆]Cl₂·trans‐[Ta₆Br₁₂(OH)₄(H₂O)₂]·18H₂O ( 1 ) and [Ta₆Br₁₂(H₂O)₆]Br₂·trans‐[Ta₆Br₁₂(OH)₄(H₂O)₂]·18H₂O ( 3 )have been solved in the triclinic space group P&1macr; (No. 2). Crystal data: 1 , a = 9.3264(2) Å, b = 9.8272(2) Å, c = 19.0158(4) Å, α = 80.931(1)?, β = 81.772(2)?, γ = 80.691(1)?; 3 , a = 9.3399(2) Å, b = 9.8796(2) Å, c = 19.0494(4) Å; α = 81.037(1)?, β = 81.808(1)?, γ = 80.736(1)?. 1 and 3 consist of two octahedral differently charged cluster entities, [Ta₆Br₁₂]²⁺ in the [Ta₆Br₁₂(H₂O)₆]²⁺ cation and [Ta₆Br₁₂]⁴⁺ in trans‐[Ta₆Br₁₂(OH)₄(H₂O)₂]. Average bond distances in the [Ta₆Br₁₂(H₂O)₆]²⁺ cations: 1 , Ta‐Ta, 2.9243 Å; Ta‐Brⁱ , 2.607 Å; Ta‐O, 2.23 Å; 3 , Ta‐Ta, 2.9162 Å; Ta‐Brⁱ , 2.603 Å; Ta‐O, 2.24 Å. Average bond distances in trans‐[Ta₆‐Br₁₂(OH)₄(H₂O)₂]: 1 , Ta‐Ta, 3.0133 Å; Ta‐Brⁱ, 2.586 Å; Ta‐O(OH), 2.14 Å; Ta‐O(H₂O), 2.258(9) Å; 3 , Ta‐Ta, 3.0113 Å; Ta‐Brⁱ, 2.580 Å; Ta‐O(OH), 2.11 Å; Ta‐O(H₂O), 2.23(1) Å. The crystal packing results in short O···O contacts along the c axes. Under the same experimental conditions, [Ta₆Cl₁₂]²⁺ oxidized to [Ta₆Cl₁₂]⁴⁺ , whereas [Nb₆X₁₂]²⁺ clusters were not affected by the Cu²⁺ ion.     

Photosubstitution reactions in potassium octacyanomolybdate(IV) and octacyanotungstate(IV) in the presence of 1,10-phenanthroline and 2,2-́bipyridyl

Substitution reactions take place following the photonic excitation of aqueous K₄M(CN)₈ (where M = Mo or W) in the presence of 1,10-phenanthroline and 2,2$\text{-}\text{?}$bipyridyl. Changes in absorbance with time show that the overall reaction is dependent on photochemical activation of potassium octacyanomolybdate(IV) and -tungstate(IV). The species [K₂Mo(CN)₄(OH)₂(phen)], [K₂W(CN)₄(OH)₂(phen)], [K₂Mo(CN)₄(OH)₂(bipy)] and [K₂W(CN)₄(OH)₂(bipy)] exist in solution. The final photosubstitution products [Mo(OH)₃(CN)(phen)₂] · 2H₂O], [Mo(OH)₃(CN)(bipy)₂] · 3H₂O, [W(OH)₃(CN)(phen)₂] · 2H₂O and [W(OH)₃(CN)(bipy)₂] · H₂O have been isolated in the solid state. Their IR spectra have been discussed. The quantum yield of the photosubstitution reactions has been determined and its variation with change of concentration of the complex as well as the H⁺ ion concentration has been studied.     

Synthesis and structures of new octahedral heterometal rhenium-osmium cluster complexes

New octahedral anionic heterometal rhenium-osmium cluster complexes [Re₅OsSe₈(OH)₆]³⁻ and [Re₄Os₂Se₈(OH)₆]²⁻ were synthesized starting from [Re₅OsSe₈Cl₆]³⁻ and [Re₄Os₂Se₈Cl₆]²⁻, respectively. They were isolated as salts of the compositions Cs₃[Re₅OsSe₈(OH)₆] · 11H₂O (I), K₃[Re₅OsSe₈(OH)₆] · 7H₂O (II), and K₂[Re₄Os₂Se₈(OH)₆] · 3H₂O (III). The protonation of the terminal OH ligands of [Re₅OsSe₈(OH)₆]³⁻ in an aqueous solution resulted in crystallization of a neutral complex [Re₅OsSe₈(H₂O)₃(OH)₃] · 12H₂O (IV). The compounds have been characterized by single-crystal X-ray diffraction analysis. The luminescence properties of [Re₅OsSe₈(OH)₆]³⁻ and [Re₄Os₂Se₈(OH)₆]²⁻ were studied. In addition, the electronic structures of the complexes were elucidated by DFT calculations.     

Trennung und Charakterisierung von Chloro-aquo-hydroxo-oxo-osmaten(IV)

Separation and Characterization of Chloro-aquo-hydroxo-oxo-osmates(IV) As a result of the acidic hydrolysis of hexachloroosmate(IV), OsCl₆^2?, and/or the careful reduction of osmium tetroxide with iron(II) sulfate in hydrochloric acid products have been obtained which have been separated by column chromatography using diethylaminoethyl cellulose. On the basis of the analytically determined Os:Cl ratios, the ionic charges that could be deduced from the elution behaviour, and the absorption spectra the products have been characterized as the monomers OsCl₅(H₂O)^?, cis-OsCl₄(OH)(H₂O)^?, fac-OsCl₃(OH)₂(H₂O)^? and mer-OsCl₃(OH)(H₂O)₂, the O-bridged dimers Cl₅Os? O? OsCl₅^4?, cis-(H₂O)Cl₄Os? O? OsCl₄(H₂O)^2?and fac-(H₂O)(OH)Cl₃Os? O? OsCl₃(OH)(H₂O)^2? and the hydrogen bridges forming OH-bridged dimers shown in “Inhaltsübersicht”.     

Hepta­aqua­tetra‐μ3‐hydroxy‐hexa‐μ2‐l‐leucine‐(l‐leucine)­tetraytterbium(III) tetrachlorozinc(II) tri­chloro­hydroxyzinc(II) tetrachloride octahydrate

The title bimetallic compound, [Yb₄(μ₃‐OH)₄(C₆H₁₃NO₂)₇(H₂O)₇][ZnCl₄][ZnCl₃(OH)]Cl₄·8H₂O, was synthesized at near physiological pH (6.0). The compound exhibits some novel structural features, including an asymmetric [Yb₄(μ₃‐OH)₄(l ‐leucine)₇(H₂O)₇]⁸⁺ complex cation in which four OH groups act as bridging ligands, linking four Yb³⁺ cations into a Yb₄O₄ structural unit. Each pair of adjacent Yb³⁺ ions is further bridged by one carboxy group from a leucine ligand. Water mol­ecules and a monodentate leucine ligand also coordinate to Yb³⁺ ions, completing their eight‐coordinate square‐antiprismatic coordination. The Yb₄(μ₃‐OH)₄(l ‐leu­cine)₇(H₂O)₇]⁸⁺ cation, the [ZnCl₄]²⁻, [ZnCl₃OH]²⁻ and Cl⁻ anions, and the lattice water mol­ecules are linked via hydrogen bonds.     

A series of new pyridine carboxamide complexes and self-assemblies with Tb(III), Eu(III), Zn(II), Cu(II) ions and their luminescent and magnetic properties

In this study, we present eight new complexes and self-assemblies of Tb(III), Eu(III), Zn(II) and Cu(II) ions with novel pyridine carboxamides, L1 [methyl 4-methyl-3-(pyridine-4-carbonylamino)benzoate] and L2 [methyl 2-methyl-3-(pyridine-4-carbonylamino)benzoate], as heterocyclic ligands. Two luminescent and spatially organized coordination compounds were obtained with the use of the solvothermal synthesis method, (1) [Tb₃(L1)₄(BTC)₃(H₂O)₃] (where BTC is benzene-1,3,5-tricarboxylic acid) and (5) [Eu(L2a)₃(H₂O)₃](H₂O)₄. As a result of one pot reaction synthesis under reflux the d-electron metal ions and self-organization of ligands gave complexes (2) [Zn(L1)₂Cl₂], (3) [Cu(L1)₂(SCN)₂(H₂O)], (4) [Cu(L1)₂Cl₂], hybrid salt (6) [(CuCl₄)^2-(L2b)₂²⁺](H₂O), (7) [Cu(L2)₂Cl₂] and 1D-chain coordination polymer (8) [Cu(L2)₂(SCN)₂]. Identification of the obtained compounds was performed on the basis of the excitation, emission, ¹H NMR, FT-IR spectra, luminescence lifetimes, SEM images, PXRD, single-crystal X-ray diffraction, MS, TGA and elemental analysis. Selected compounds were also analyzed in terms of their potential magnetic properties.     

A series of new oxo-vanadium(IV) complexes with octahedral coordinated vanadium centers

A series of new oxo-vanadium(IV) complexes, [VOCl0.69(OH)0.31 (2,2′-bipy)2]Cl·2H2O (1, 2,2′-bipy?=?2,2′-bipyridine) [(VO)₂Cl₄(4,4'-bipy)₃ (H₂O)₂] (2, 4,4'-bipy?=?4,4'-bipyridine), [VO(ida)(H₂O)]_n (3, H₂ida?=?iminodiacetic acid), and [(VO)₂(oa)₄]_n·4n(H₃O)·n(H₂O) (4, H₂oa?=?oxalic acid), have been synthesized and structurally characterized. 1 contains a [VOCl_0.69(OH)_0.31(2,2′-bipy)₂]⁺ cation, Cl ^– anion and two free H₂O molecules. 2 exhibits a binuclear centrosymmetric moiety built up from two [VOCl₂(4,4'-bipy)(H₂O)] units and one bridging 4,4'-bipy ligand, which provides a rare example of a 4,4'-bipy molecule acting as monodentate ligand. 3 displays a neutral chain [VO(ida)(H₂O)]_n constructed by the linkages of [VO(H₂O)]²⁺ units and ida^2? bridging ligands, while 4 offers the only example of three kinds of oa^2- ligands coexisting within the same anionic chain [(VO)₂(oa)₄^4-]_n. Their spectroscopic properties were investigated, and the magnetic susceptibility of 4 shows antiferromagnetic behavior.     

Synthesis,infrared spectra and thermal investigation of gold(III) and zinc(II) urea complexes. A new procedure for the synthesis of basic zinc carbonate

Reaction of urea with sodium tetrachloroaurate(III) dihydrate and zinc(II) chloride has been investigated at room and elevated temperature (～90°C) producing three new compounds: [Au(urea)₄]Cl₃·2H₂O, [Au₂(NH₂)₂Cl₂(NCO)(OH)]·H₂O and 2ZnCO₃·3Zn(OH)₂. The infrared spectra were recorded and the observed bands were assigned. The binuclear gold complex and basic zinc carbonate basic were also investigated by thermal analysis, and general mechanisms describing their decompositions are suggested.     

Molecular modeling,spectral, and biological studies of 4-formylpyridine-4 N-(2-pyridyl) thiosemicarbazone (HFPTS) and its Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II), Hg(II), and UO2(II) complexes

The present work describes the preparation and characterization of some metal ion complexes derived from 4-formylpyridine-⁴ N-(2-pyridyl)thiosemicarbazone (HFPTS). The complexes have the formula; [Cd(HFPTS)₂H₂O]Cl₂, [CoCl₂(HPTS)]·H₂O, [Cu₂Cl₄(HPTS)]·H₂O, [Fe (HPTS)₂Cl₂]Cl·3H₂O, [Hg(HPTS)Cl₂]·4H₂O, [Mn(HPTS)Cl₂]·5H₂O, [Ni(HPTS)Cl₂]·2H₂O, [UO₂(FPTS)₂(H₂O)]·3H₂O. The complexes were characterized by elemental analysis, spectral (IR, ¹H-NMR and UV–Vis), thermal and magnetic moment measurements. The neutral bidentate coordination mode is major for the most investigated complexes. A mononegative bidentate for UO₂(II), and neutral tridentate for Cu(II). The tetrahedral arrangement is proposed for most investigated complexes. The biological investigation displays the toxic activity of Hg(II) and UO₂(II) complexes, whereas the ligand displays the lowest inhibition activity toward the most investigated microorganisms.     

Synthesis and crystal structures of supramolecular compounds of polynuclear aluminum(III) aqua hydroxo complexes with cucurbit[6]uril

Supramolecular compounds of the di-, trideca-, and triacontanuclear aluminum aqua hydroxo complexes, viz., [Al₂(OH)₂(H₂O)₈]⁴⁺, [Al₁₂(AlO₄)(OH)₂₄(H₂O)₁₂]⁷⁺, and [Al₃₀O₈(OH)₅₆(H₂O)₂₆]¹⁸⁺, respectively, with the organic macrocyclic cavitand cucurbit[6]uril (C₃₆H₃₆N₂₄O₁₂) were prepared by evaporation of aqueous solutions of aluminum nitrate and cucurbit[6]uril after the addition of pyridine, ammonia, KOH, or NaOH at pH 3.1–3.8. X-ray diffraction study demonstrated that the aqua hydroxo complexes are linked to the macrocycle through hydrogen bonds between the hydroxo and aqua ligands of the polycations and the portal oxygen atoms of cucurbit[6]uril. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 261—268, February, 2006.     

Einige Reaktionen mit [Mo6Cl8]Cl4

Some Reactions with [Mo₆Cl₈]Cl₄ The reaction of [Mo₆Cl₈]Cl₄ with different chemical agents has been investigated: The methoxylation depends on the CH₃O^? concentration in CH₃OH. The reaction with HF leads to a partial fluorinated [Mo₆Cl₈] product. With NH₄F (NH₄)₂[Mo₆Cl₈]F₆ in formed, the hydrolysis of which leads to [Mo₆Cl₈]F₃(OH) · 2.5 H₂O. This compound can be decomposed thermically into [Mo₆Cl₈]O₂. [Mo₆Br₈]F₆^2? on hydrolysis leads to [Mo₆Br₈]F₃(OH) · 5 H₂O. With CsF Cs₂[Mo₆Cl₈]F₆ is formed, which by hydrolysis is transformed into [Mo₆Cl₈]F₃(OH) · 2.5 H₂O and possibly to [Mo₆Cl₈]F₄ · xH₂O(?). In reaction of [Mo₆Cl₈]Cl₄ with H₂SO₄ one gets [Mo₆Cl₈](SO₄)₂. Salts e. g. [(C₆H₅)₄As]₂[Mo₆Cl₈](OC₆F₅)₆ and adducts e. g. [Mo₆Cl₈](OC₆F₅)₄ · 2 HMPA are prepared. The compounds have been characterized by X-ray powder-diagramms and by IR-spectra.     

Syntheses and crystal structures of supramolecular compounds of tetranuclear ZrIV and HfIV aqua hydroxo complexes with macrocyclic cavitand cucurbituril

Slow evaporation of hydrochloric acid solutions of zirconium(iv) or hafnium(iv) oxochlorides and cucurbituril in air afforded compounds with composition [M₄(OH)₈(H₂O)₁₆]Cl₈·(C₃₆H₃₆N₂₄O₁₂)·16H₂O, where M = Zr (1) or Hf (2). According to the X-ray diffraction data, complexes 1 and 2 are isostructural. Their crystal structures can be described as packings of polymer chains consisting of alternating cucurbituril molecules and tetranuclear cations [M₄(OH)₈(H₂O)₁₆]⁸⁺ linked to each other via an extensive network of hydrogen bonds. Compound 2 is the first structurally characterized tetranuclear hafnium aqua complex.     

A2Ca[B4O5(OH)4]2·8H2O(A=Rb,Cs)硼氧酸盐复盐的合成与表征

硼氧酸盐晶体结构复杂，因此出现了许多具有特殊物理性能的晶体功能材料犤１，２犦，尤其是重稀碱金属硼氧酸盐（或复盐），如CsLiB６O１０犤３犦、LiRbB４O７犤４犦和CsB３O５（CBO）犤５犦都是非线性光学材料。一些学者对铷、铯的偏硼氧酸盐、四硼氧酸盐和五硼氧酸盐的合成、性质及晶体结构等进行过研究犤６～９犦。硼氧酸盐复盐，大多为碱金属和碱土金属、碱金属和碱金属及碱土金属和碱土金属的硼氧酸盐犤１０犦，如自然界存在的钠硼解石狖NaCa犤B５O６（OH）６犦·５H２O狚、硼钠镁石狖Na２Mg犤B６O８（OH）４犦２·６H２O…