Organophosphonate derivatives of titanium and niobium alkoxoanions

The organophosphonate-substituted alkoxides [Bu₄ⁿN]₂[{Ti(OMe)₃(O₃PPh)}₂] (1) and [Bu₄ⁿN]₂[{Nb(OMe)₃(O₃PPh)}₂(μ-O)] (2) have been prepared from [Bu₄ⁿN][PhPO₃H] and the metal alkoxides Ti(OMe)₄ or Nb(OMe)₅ respectively. In 1, the bridging phenylphosphonates occupy trans coordination sites, whereas in 2, a cis–bridging geometry is adopted.     

Structural studies in main group chemistry : XXII. Structural and tin-119 mössbauer studies of some five-coordinate triorganotin anions

The structures of two complexes, [Ph₃PCH₂Ph]⁺[Bu₃SnCl₂⁻]⁻ and [Ph₃AsCH₂COPh]⁺[Ph₃SnCl₂]⁻, have been determined by X-ray diffraction. Both materials are monoclinic, space group P2_1/c. Unit cell data for [Ph₃PCH₂Ph]⁺−[Bu₃SnCl₂]⁻ are a 9.8521(6), b 16.9142(4), c 22.3517(7) Å, β 91.4235(9)°; and for [Ph₃AsCH₂COPh]⁺[Ph₃SnCl₂]⁻ a 34.9760(3), b 11.1290(5), c 24.2410(2) Å, β 108.56(2)°, and both consist of the component ionic species. The organotin anions each have trigonal bipyramidal geometry with equatorial organic groups and axial halogens. In the [Ph₃SnCl₂]⁻ anion the two Sn---Cl bond distances are the same (2.58(1) and 2.60(1) Å), but in [Bu₃SnCl₂]⁻, as in [Me₃SnCl₂]⁻, they are substantially different (2.573(7) and 2.689(6) Å). The Sn---C bond distances also vary: [Ph₃SnCl₂]⁻ 2.15(4), 2.16(3) and 2.25(5); [Bu₃SnCl₂]⁻ 2.21(1), 2.20(2) and 2.29(2) Å. Tin-119 Mössbauer data for these and several other similar complexes are also reported.     

2‐Methyl‐1,3‐disulfoimidazolium polyoxometalate hybrid catalytic systems as equivalent safer alternatives to concentrated sulfuric acid in nitration of aromatic compounds

Ionic liquid‐derived polyoxometalate salts [mdsim]₃[PM₁₂O₄₀] (where M = W and Mo) of two heteropolyacids H₃PW₁₂O₄₀.nH₂O and H₃PMo₁₂O₄₀.nH₂O were synthesized using 2‐methyl‐1,3‐disulfoimidazolium chloride ([mdsim][Cl]) ionic liquid and the corresponding heteropolyacids. Three equivalents of [mdsim][Cl] were treated with the respective Keggin‐structured heteropolyacids (one equivalent) in aqueous medium at room temperature to afford the water‐stable ionic polyoxometalates as acidic solids. They were completely characterized using spectroscopic and other analytical techniques including thermal analysis and Hammett acidity studies. The inherent Brønsted acidic properties of ─SO₃H group of these polyoxometalate salts were studied for the nitration of aromatic compounds with 69% HNO₃ at normal temperature and 80°C without use of any external concentrated sulfuric acid. These strongly acidic polyoxometalates display good recyclability and efficient reusability.     

Structural and Spectral Characterization of Two Charge-Transfer Salts Formed by Ferrocenyl and Polyoxometalate Units

Two charge-transfer (CT) salts based on the ferrocenyl cation CpFeCpCH₂N⁺(CH₃)₃ and Keggin-type anion [PW₁₂O₄₀]³⁻ or [SiMo₁₂O₄₀]⁴⁻ with the ratio of ferrocenyl:polyanion of 3:1 or 4:1, [CpFeCpCH₂N(CH₃)₃]₃[PW₁₂O₄₀] (1) and [CpFeCp-CH₂N⁺(CH₃)₃]₄[SiMo₁₂O₄₀] (2), were synthesized in high yields (68–71%) by traditional solution synthetic method and their structures were determined by X-ray diffraction analysis. The two salts both crystallize in triclinic space group P[`1] P\overline{1} and show the close interaction of the cyclopentadienyl ligand with the surface of the polyoxometalate. The UV–Vis diffuse reflectance spectra of 1 and 2 in the solid state indicate the presence of a new absorption band at λ _max = 550 and 630 nm, respectively, attributed to charge-transfer transitions between the ferrocenyl donors and the POM acceptors. The large difference of the shapes and positions of fluorescence emission bands of salts from the start materials also suggested the occurrence of a charge transfer process between the ferrocenyl cation and polyanion.     

Hydrothermal syntheses, crystal structures of three new organic–inorganic hybrids constructed from Keggin-type [BW12O40] clusters and transition metal complexes

Three new organic–inorganic hybrid compounds constructed from Keggin-type polyanions and transition metal complexes, [Mn(2,2′-bipy)₃]_1.5[BW₁₂O₄₀Mn(2,2′-bipy)₂(H₂O)]·0.25H₂O (1), [Fe(2,2′-bipy)₃]_1.5[BW₁₂O₄₀Fe(2,2′-bipy)₂(H₂O)]·0.5H₂O (2) and [Cu₂(phen)₂(OH)₂]₂H[Cu(H₂O)₂{BW₁₂O₄₀Cu_0.75(phen)(H₂O)}₂]·1.5H₂O (3), have been hydrothermally synthesized and characterized by elemental analyses, IR, TGA and single-crystal X-ray diffraction. Compounds 1 and 2 are isostructural and both exhibit monosupporting polyoxometalate cluster structure, each of which contains a [BW₁₂O₄₀]⁵⁻ cluster decorated by one transition metal complex. Compound 3 contains a bisupporting polyoxometalate cluster anion where two {Cu_0.75(phen)(H₂O)}^0.75+ fragments are supported on the polyoxometalate dimer {Cu(H₂O)₂(BW₁₂O₄₀)₂}⁸⁻, this represents the first bisupporting polyoxometalate cluster based on a Keggin-type polyoxometalate dimer, which are further packed together via π–π stacking contacts into an extended 1-D chain.     

Kristallstrukturen,spektroskopische Charakterisierung und Normalkoordinatenanalyse von (n‐Bu4N)2[M(ECN)4] (M = Pd,Pt; E = S,Se)

Crystal Structures, Spectroscopic Analysis, and Normal Coordinate Analysis of ( n ‐Bu₄N)₂[M(ECN)₄] (M = Pd, Pt; E = S, Se) The reaction of (NH₄)₂[PdCl₄] or K₂[PtCl₄] with KSCN or KSeCN in aqueous solutions yields the complex anions [Pd(SCN)₄]^2–, [Pt(SCN)₄]^2– and [Pt(SeCN)₄]^2–, which are converted into (n‐Bu₄N) salts with (n‐Bu₄N)HSO₄. (n‐Bu₄N)₂[Pd(SeCN)₄] is formed by treatment of (n‐Bu₄N)₂[PdCl₄] with (n‐Bu₄N)SeCN in acetone. X‐ray structure determinations on single crystals of (n‐Bu₄N)₂[Pd(SCN)₄] (monoclinic, space group P2₁/n, a = 13.088(3), b = 12.481(2), c = 13.574(3) Å, β = 91.494(15)°, Z = 2), (n‐Bu₄N)₂[Pd(SeCN)₄] (monoclinic, space group P2₁/n, a = 13.171(2), b = 12.644(2), c = 13.560(2) Å, β = 91.430(11)°, Z = 2) and (n‐Bu₄N)₂[Pt(SeCN)₄] (monoclinic, space group P2₁/n, a = 13.167(2), b = 12.641(1), c = 13.563(2) Å, β = 91.516(18)°, Z = 2) reveal, that the compounds crystallize isotypically and the complex anions are centrosymmetric and approximate planar. In the Raman spectra the metal ligand stretching modes of (n‐Bu₄N)₂[Pd(SCN)₄] ( 1 ) and (n‐Bu₄N)₂[Pt(SCN)₄] ( 3 ) are observed in the range of 260–303 cm^–1 and of (n‐Bu₄N)₂[Pd(SeCN)₄] ( 2 ) and (n‐Bu₄N)₂[Pt(SeCN)₄] ( 4 ) in the range of 171–195 cm^–1. The IR and Raman spectra are assigned by normal coordinate analysis using the molecular parameters of the X‐ray determination. The valence force constants are f_d(PdS) = 1.17, f_d(PdSe) = 1.17, f_d(PtS) = 1.44 and f_d(PtSe) = 1.42 mdyn/Å. The ⁷⁷Se NMR resonances are 23 for 2 , –3 for 4 and the ¹⁹⁵Pt NMR resonances 549 for 3 and 130 ppm for 4 .     

Synthesis and reactivity of neodymium(III) amido-tethered N-heterocyclic carbene complexes

The reaction of the heteroleptic Nd(III) iodide, [Nd(L′)(N″)(μ-I)] with the potassium salts of primary aryl amides [KN(H)Ar′] or [KN(H)Ar^*] affords heteroleptic, structurally characterised, low-coordinate neodymium amides [Nd(L′)(N″)(N(H)Ar′)] and [Nd(L′)(N″)(N(H)Ar^*)] cleanly (L′ = t-BuNCH₂CH₂[C{NC(SiMe₃)CHNt-Bu}], N″ = N(SiMe₃)₂, Ar′ = 2,6-Dipp₂C₆H₃, Dipp = 2,6-Prⁱ₂C₆H₃, Ar^* = 2,6-(2,4,6-Prⁱ₃C₆H₂)₂C₆H₃). The potassium terphenyl primary amide [KN(H)Ar^*] is readily prepared and isolated, and structurally characterised. Treatment of these primary amide-containing compounds with alkali metal alkyl salts results in ligand exchange to give alkali metal primary amides and intractable heteroleptic Nd(III) alkyl compounds of the form [Nd(L′)(N″)(R)] (R = CH₂SiMe₃, Me). Attempted deprotonation of the Nd-bound primary amide in [Nd(L′)(N″)(N(H)Ar^*)] with the less nucleophilic phosphazene superbase Bu^tNP{NP(NMe₂)₃}₃ resulted in indiscriminate deprotonations of peripheral ligand CH groups.     

Synthesen und NMR‐Untersuchungen von Salzen mit den neuen Anionen [PtXn(CF3)6‐n]2— (n = 0 ‐ 5, X = F,OH, Cl,CN) und die Kristallstrukturanalyse von K2[(CF3)2F2Pt(μ‐OH)2PtF2(CF3)2]·2H2O

Syntheses and NMR Spectroscopic Ivestigations of Salts containing the Novel Anions [PtX_n(CF₃)_6‐n]^2— (n = 0 ‐ 5, X = F, OH, Cl, CN) and Crystal Structure of K₂[(CF₃)₂F₂Pt(μ‐OH)₂PtF₂(CF₃)₂]·2H₂O The first syntheses of trifluoromethyl‐complexes of platinum through fluorination of cyanoplatinates are reported. The fluorination of tetracyanoplatinates(II), K₂[Pt(CN)₄], and hexacyanoplatinates(IV), K₂[Pt(CN)₆], with ClF in anhydrous HF leads after working up of the products to K₂[(CF₃)₂F₂Pt(μ‐OH)₂PtF₂(CF₃)₂]·2H₂O. The structure of the salt is determined by a X‐ray structure analysis, P2₁/c (Nr. 14), a = 11.391(2), b = 11.565(2), c = 13.391(3)Å, β = 90.32(3)°, Z = 4, R₁ = 0.0326 (I > 2σ(I)). The reaction of [Bu₄N]₂[Pt(CN)₄] with ClF in CH₂Cl₂ generates mainly cis‐[Bu₄N]₂[PtCl₂(CF₃)₄] and fac‐[Bu₄N]₂[PtCl₃(CF₃)₃], but in contrast that of [Bu₄N]₂[Pt(CN)₆] with ClF in CH₂Cl₂ results cis‐[Bu₄N]₂[PtX₂(CF₃)₄], [Bu₄N]₂[PtX(CF₃)₅] (X = F, Cl) and [Bu₄N]₂[Pt(CF₃)₆]. In the products [Bu₄N]₂[PtX_n(CF₃)_6‐n] (X = F, Cl, n = 0—3) it is possibel to exchange the fluoro‐ligands into chloro‐ and cyano‐ligands by treatment with (CH₃)₃SiCl und (CH₃)₃SiCN at 50 °C. With continuing warming the trifluoromethyl‐ligands are exchanged by chloro‐ and cyano‐ligands, while as intermediates CF₂Cl and CF₂CN ligands are formed. The identity of the new trifluoromethyl‐platinates is proved by ¹⁹⁵Pt‐ and ¹⁹F‐NMR‐spectroscopy.     

Novel Antimony Complexes: [Ph4Sb]4 +[Sb4I16]4− · 2Me2C=O and [Ph4Sb]3 +[Sb5I18]3−

The [Ph₄Sb]₄ ⁺[Sb₄I₁₆]^4– · 2Me₂C=O and [Ph₄Sb]₃ ⁺[Sb₅I₁₈]^3– complexes were synthesized by reacting tetraphenylstibonium salts Ph₄SbX (X = I, OSO₂C₆H₄Me-4) with antimony triiodide in acetone. According to X-ray diffraction data, their tetra- and pentanuclear anions [Sb₄I₁₆]^4– and [Sb₅I₁₈]^3– have cyclic and linear structure, respectively.     

Zur solvensfreien Darstellung von Tetramethylammoniumsalzen: Synthese und Charakterisierung von [N(CH3)4]2[C2O4], [N(CH3)4][CO3(CH3)], [N(CH3)4][NO2], [N(CH3)4][CO2H] und [N(CH3)4][O2C(CH2)2CO2(CH3)]

Solvent-free Synthesis of Tetramethylammonium Salts: Synthesis and Characterization of [N(CH₃)₄]₂[C₂O₄], [N(CH₃)₄][CO₃CH₃], [N(CH₃)₄][NO₂], [N(CH₃)₄][CO₂H], and [N(CH₃)₄][O₂C(CH₂)₂CO₂CH₃] A general procedure to synthesize tetramethylammonium salts is presented. Several tetramethylammonium salts were prepared in a crystalline state by solvent-free reaction of trimethylamine and different methyl compounds at mild conditions: [N(CH₃)₄]₂[C₂O₄] (cubic; a = 1 114.8(3) pm), [N(CH₃)₄][CO₃CH₃] (P2₁/n; a = 813.64(3), b = 953.36(3), c = 1 131.3(4) pm, β = 90.03(1)°), [N(CH₃)₄][NO₂] (Pmmn; a = 821.2(4), b = 746.5(3), c = 551.5(2) pm), [N(CH₃)₄][CO₂H] (Pmmn; a = 792.8(7), b = 791.7(3), c = 563.3(4) pm) and [N(CH₃)₄][O₂C(CH₂)₂CO₂CH₃] (P2₁; a = 731.1(2), b = 826.4(3), c = 1 025.2(3) pm, β = 110.1(1)°). The tetramethylammonium salts were characterized by IR-spectroscopy and X-ray diffraction. The crystal structures of the methylcarbonate and the nitrite are described.     

Neue dimere Goldselenolate: Darstellung und strukturelle Charakterisierung von [(n-C4H9)4N]2[AuSSeCC(CN)2]2 und [(n-C4H9)4N]2[AuSe2CC(CN)2]2

New Dimeric Gold Selenolates: Preparation and Characterization of [(n-C₄H₉)₄N]₂[AuSSeC ? C(CN)₂]₂ and [(n-C₄H₉)₄N]₂[AuSe₂C ? C(CN)₂]₂ The preparation and structural characterization of the dimeric Au^I complexes of 1,1-dicyanoethene-2,2-thioseleonlate (i-mnts) and 1,1-dicyanoethene-2,2-diselenolate (i-mns), isolated as Bu₄N salts, are described. They are isotype (monoclinic, space group P2₁/c, Z = 2) with lattice parameters: (Bu₄N)₂[Au(i-mnts)]₂; a = 14.078(3) Å, b = 8.912(3) Å, c = 20.142(4) Å, β = 106.32(5)°; (Bu₄N)₂[Au(i-mns)]₂; a = 13.998(3) Å, b = 9.125(3) Å, c = 20.039(2) Å, β = 105.12(5)°. Ab initio Hartree-Fock calculations based on the experimentally determined structure yield a positive value of the Au? Au bonding order suggesting weak bonding interactions between the d¹⁰ metal centres.     

Darstellung und Kristallstruktur von K4[SnO3]

Preparation and Crystal Structure of K₄[SnO₃] K₄[SnO₃] crystallizes with the K₄[PbO₃] structure in the orthorhombic spacegroup Pbca (No. 61) with the lattice constants a = 652.2(3) pm, b = 1 112.1(5) pm and c = 1 893.7(7) pm. In the structure isolated ψ-tetrahedral anions [Sn^IIO₃]^4? are arranged in layers perpendicular [001]. The structure of K₄[SnO₃] will be compared with those of stannates and plumbates of composition A₄[M^IIO₃] (A = Na, K, Rb, Cs) and with the known potassium stannates(II).     

Kristallstrukturen,Schwingungsspektren und Normalkoordinatenanalyse von (n‐Bu4N)2[Os(NCS)6] und (n‐Bu4N)3[Os(NCS)6]

Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of ( n ‐Bu₄N)₂[Os(NCS)₆] and ( n ‐Bu₄N)₃[Os(NCS)₆] By tempering the solid mixture of the linkage isomers (n‐Bu₄N)₃[Os(NCS)_n(SCN)_6–n] n = 0–5 for a longer time at temperatures increasing from 60 to 140 °C the homoleptic (n‐Bu₄N)₃[Os(NCS)₆] is formed, which on oxidation with (NH₄)₂[Ce(NO₃)₆] in acetone yields the corresponding Os^IV complex (n‐Bu₄N)₂[Os(NCS)₆]. X‐ray structure determinations on single crystals of (n‐Bu₄N)₂[Os(NCS)₆] (1) (triclinic, space group P 1, a = 12.596(5), b = 12.666(5), c = 16.026(5) Å, α = 88.063(5), β = 80.439(5), γ = 88.637(5)°, Z = 2) and (n‐Bu₄N)₃[Os(NCS)₆] ( 2 ) (cubic, space group Pa 3, a = 24.349(4) Å, Z = 8) have been performed. The nearly linear thiocyanate groups are coordinated with Os–N–C angles of 172.3–177.7°. Based on the molecular parameters of the X‐ray determinations the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constant f_d(OsN) is 2.3 ( 1 ) and 2.10 mdyn/Å ( 2 ).     

Hydrothermal synthesis of a mixed-valence hexamolybdate cluster: crystal structure of [HN(CH2CH2)3N]2[HMoVMoVI5O19]·[N(CH2CH2)3N]

The hydrothermal reaction of MoO₃, V, Na₂WO₄· 2H₂O, [N(CH₂CH₂)₃N](1,4-diazabicyclo[2.2.2] octane), and H₂O at 160°C for 90h gave dark-brown crystals of [HN(CH₂CH₂)₃N]₂[HMo^VMo^VI ₅O¹⁹]·[N(CH₂CH₂)₃N], (1), in 40% yield. Complex (1) is the first one-electron reduced mixed-valence hexamolybdate to be crystallized and structurally characterized. The crystal structure of (1) consists of discrete [HMo^VMo^VI ₅O₁₉]^2– anions, [HN-(CH₂CH₂)₃N]⁺ cations, and neutral [N(CH₂CH₂)₃N] molecules of crystallization.     

Synthesis,Characterization and Assessment of the Antioxidant Activity of Cu(II), Zn(II) and Cd(II) Complexes Derived from Scorpionate Ligands

Seeking to enrich the yet less explored field of scorpionate complexes bearing antioxidant properties, we, here, report on the synthesis, characterization and assessment of the antioxidant activity of new complexes derived from three scorpionate ligands. The interaction between the scorpionate ligands thallium(I) hydrotris(5-methyl-indazolyl)borate (TlTp^4Bo,5Me), thallium(I) hydrotris(4,5-dihydro-2H-benzo[g]indazolyl)borate (TlTp^a) and potassium hydrotris(3-tert-butyl- pyrazolyl)borate (KTp^tBu), and metal(II) chlorides, in dichloromethane at room temperature, produced a new family of complexes having the stoichiometric formula [M(Tp^4Bo,5Me)₂] (M = Cu, 1; Zn, 4; Cd, 7), [M(Tp^a)₂] (M = Cu, 2; Zn, 5; Cd, 8), [Cu(Hpz^tBu)₃Cl₂] (3), [Zn(Tp^tBu)Cl] (6) and [Cd(Bp^tBu)(Hpz^tBu)Cl] (9). The obtained metal complexes were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance and elemental analysis, highlighting the total and partial hydrolysis of the scorpionate ligand Tp^tBu during the synthesis of the Cu(II) complex 3 and the Cd(II) complex 9, respectively. An assessment of the antioxidant activity of the obtained metal complexes was performed through both enzymatic and non-enzymatic assays against 1,1-diphenyl-2-picryl- hydrazyl (DPPH^·), 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^+·), hydroxyl (HO^·), nitric oxide (NO^·), superoxide (O₂⁻) and peroxide (OOH^·) radicals. In particular, the complex [Cu(Tp^a)₂]⋅0.5H₂O (2) exhibited significant antioxidant activity, as good and specific activity against superoxide (O₂^−·), (IC50 values equal to 5.6 ± 0.2 μM) and might be identified as auspicious SOD-mimics (SOD = superoxide dismutase).     

Evaluation and comparison of global scalar properties for the simultaneous interaction of ionic liquids with thiophene and pyridine

Ab initio studies were carried out with mixtures containing ionic liquid with thiophene and pyridine for studying the simultaneous interaction. Global scalar properties such as HOMO/LUMO energies, HOMO–LUMO energy gap, chemical hardness, chemical potential, electronegativity, global hardness, global softness and electrophilicity index were determined for clusters containing ionic liquids with thiophene and pyridine. Ionic liquids containing: 1-butyl-3-methylpyrrolidinium [BUMPYR], 1-benzyl-3-methyimidazolioum [BeMIM] and 1-butyl-3-methylpyridinium [BUMPY] cations combined with inorganic anions containing fluorine ([BF₄] and [PF₆]) were studied in this work. [BeMIM][BF₄] (1-benzyl-3-methyimidazolioum tetrafluoroborate) with a HOMO–LUMO energy gap of 0.1882 Hartrees was found to be the most effective IL. Further a ranking based on all the mentioned scalar parameters also pointed out [BeMIM][BF₄] to be the most desirable IL. The overall ranking after taking into considerations all factors followed: [BeMIM][BF₄] > [BUMPYR][BF₄] > [BUMPY][PF₆] > [BUMPY][BF₄] > [BUMPYR][PF₆]. To validate the findings, infinite dilution activity coefficients were predicted using the quantum chemical based COSMO-RS methodology which gave the same trend as observed using scalar properties.     

Facile preparation of an α-Keggin-type [H3W12O40] complex: Does it exist in aqueous solution?

The formation processes of α-Keggin-type [H₂W₁₂O₄₀]⁶⁻ and [H₃W₁₂O₄₀]⁵⁻ complexes were investigated in aqueous W^VI (0.05–0.50 M) solutions. The formation of [H₂W₁₂O₄₀]⁶⁻ was ascertained by the appearance of a ¹⁸³W NMR line at −117 ppm, but no evidence was found for the existence of [H₃W₁₂O₄₀]⁵⁻ in the solution at the accessible pH range. The addition of (CH₃)₄N⁺ (Me₄N⁺) to the W^VI solution directly precipitated the (Me₄N)₆[H₂W₁₂O₄₀] salt. On the other hand, the addition of the larger Bu₄N⁺ cation precipitates the (Bu₄N)_4.5H_0.5[H₃W₁₂O₄₀] salt, because a naked proton formed during the crystallization process or in the solid state may enter into the Keggin shell to produce [H₃W₁₂O₄₀]⁵⁻. This explanation is based on the fact that [H₂W₁₂O₄₀]⁶⁻ is not spontaneously converted into [H₃W₁₂O₄₀]⁵⁻ in acidified aqueous solution. On the basis of their voltammetric properties, a simple diagnostic criterion was developed to distinguish between [H₂W₁₂O₄₀]⁶⁻ and [H₃W₁₂O₄₀]⁵⁻.     

Tetraalkylammonium fluorooxoperoxovanadates

Summary Compounds crystallizing from theMOH-HF-V₂O₅-H₂O₂-H₂O (M=N(CH₃)₄, N(C₂H₅)₄, N(C₄H₉)₄) system have been characterized by elemental analysis, vibrational spectra, and X-ray powder patterns. Besides [N(CH₃)₄]₂[VO(O₂)₂F]·2H₂O (1) and [N(CH₃)₄]₃[V₂O₂(O₂)₄F] (2) which correspond to the known compoundsM ₂[VO(O₂)₂F] (M=K, NH₄, Cs) and (NH₄)₃[V₂O₂(O₂)₄F]·2H₂O, respectively, complexes of two new types have been obtained: [N(C₂H₅)₄]₂[V₂O_5–x (O₂) _x F₂]·H₂O(x0.25,3) and the first trinuclear peroxo complex of vanadium(V), [N(C₄H₉)₄]₂[V₃O₃(O₂)₄F₃]·6H₂O(4).

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Tetraalkylammonium-Fluorooxoperoxovanadate

Zusammenfassung Aus dem SystemMOH-HF-V₂O₅-H₂O₂-H₂O (M=N(CH₃)₄), N(C₂H₅)₄, N(C₄H₉)₄) kristallisierende Verbindungen wurden mittels Elementaranalyse, Schwingungsspektroskopie und Röntgendiffraktion charakterisiert. Neben [N(CH₃)₄]₂[VO(O₂)₂F]·2H₂O (1) und [N(CH₃)₄]₃][V₂O₂(O₂)₄F] (2), welche den bekannten VerbindungenM ₂[VO(O₂)₂F] (M=K, NH₄, Cs) und (NH₄)₃[V₂O₂(O₂)₄)F]·2H₂O entsprechen, wurden zwei neue Typen von Komplexen erhalten: [N(C₂H₅)₄]₂[V₂O_5–x (O₂) _x F₂]·H₂O (x0.25,3) und der erste dreikernige Peroxokomplex von Vanadium(V), [N(C₄H₉)₄]₂[V₃O₃(O₂)₄F₃]·6H₂O (4).

     

[TMPA]4[Si8O20] · 34 H2O and [DDBO]4[Si8O20] · 32 H2O are heteronetwork clathrates with 1,1,4,4-tetramethylpiperazinium (TMPA) and 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane (DDBO) guest cations

[TMPA]₄[Si₈O₂₀] · 34 H₂O ( 1 ) and [DDBO]₄[Si₈O₂₀] · 32 H₂O ( 2 ) have been prepared by crystallization from aqueous solutions of the respective quaternary alkylammonium hydroxide and SiO₂. The crystal structures have been determined by single-crystal X-ray diffraction. 1 : Monoclinic, a = 16.056(2), b = 22.086(6), c = 22.701(2) Å, β = 90.57(1)° (T = 210 K), space group C2/c, Z = 4. 2 : Monoclinic, a = 14.828(9), b = 20.201(7), c = 15.519(5) Å, β = 124.13(4)° (T = 255 K), space group P2₁/c, Z = 2. The polyhydrates are structurally related host-guest compounds with three-dimensional host frameworks composed of oligomeric [Si₈O₂₀]^8? anions and H₂O molecules which are linked via hydrogen bonds. The silicate anions possess a cube-shaped double four-ring structure and a characteristic local environment formed by 24 H₂O molecules and six cations (TMPA, [C₈H₂₀N₂]²⁺, or DDBO, [C₈H₁₈N₂]²⁺). The cations themselves reside as guest species in large, irregular, cage-like voids. Studies employing ²⁹Si NMR spectroscopy and the trimethylsilylation method have revealed that the saturated aqueous solutions of 1 and 2 contain high proportions of double four-ring silicate anions. Such anions are also abundant species in the saturated solution of the heteronetwork clathrate [DMPI]₆[Si₈O₁₈(OH)₂] · 48.5 H₂O ( 3 ) with 1,1-dimethylpiperidinium (DMPI, [C₇H₁₆N]⁺) guest cations.     

Self-assembly morphology and packing structures depend on the ‘head’ of organic cations anchored on polyoxometalate anions in hybrids

Two organic-polyoxometalates (organic-POMs) hybrids were constructed by fan-shaped 1-methyl-3-[3, 4, 5-tris(octadecyloxy) benzyl]imidazolium salts (labelled as I–Cl) and triethyl-[3, 4, 5-tris (octadecyloxy) benzyl] ammonium salts (labelled as Q–Cl) and Keggin anions [SiW₁₂O₄₀]^4? by electrostatic interaction. Self-assembled behaviours of two aggregates in organic solvent and solid state were investigated in detail by scanning electron microscopy, transmission electron microscopy and X-ray analysis. The mixed solution of chloroform–methanol or chloroform–acetone provided the stable environment for aggregates and aggregates showed a uniform micron size. X-ray analysis results showed that flower-like aggregates morphology of I₄[SiW₁₂O₄₀] based on imidazole ring as ‘head’ in organic cations was formed by the stacking of multilamellar discs and kept the lamellar structure in solid state. Bulk thorn spheres appeared in Q₄[SiW₁₂O₄₀] aggregates, which were formed by closely interspersed of lots flatted blocks with hexagonal structure characteristics in solid state. The comprehension for the self-assembly morphology and solid structure of organic-polyoxometalate hybrids would help us to use easily modified organic moiety and functional inorganic polyoxoanions as blocks to build novel and giant supramolecular architecture.