Potassium-ionic conduction in the gallate-ferrite solid electrolytes

New potassium-conducting solid electrolytes in the mixed gallate-ferrite systems (1 − x)Ga₂O₃ · xFe₂O₃ · 0.25TiO₂ · K₂O and 1.5[(1 − x)Ga₂O₃ · xFe₂O₃] · TiO₂ · 2K₂O are synthesized and studied. The electrolytes exhibit high ionic conductivity in the test temperature range of 300 to 750°C (above 10⁻² S/cm at 300°C and above 10⁻¹ S/cm at 700°C). An increase in the conductivity with increasing concentration of iron in the specimens is a general tendency. Possible reasons for the effect of Ga/Fe ratio in the structure of solid electrolytes on their transport properties are discussed.     

Acenaphthylene-1,2-diamine radical cation. Molecular structure of the [(dpp-BIAN)H2]·+[X]− complex ((dpp-BIAN)H2 is N,N′-bis(2,6-diisopropylphenyl)-acenaphthylene-1,2-diamine; X = Cl or I)

Oxidation of N,N′-bis(2,6-diisopropylphenyl)acenaphthylene-1,2-diamine (dpp-BIAN)H₂ with silicon tetrachloride or mercury(II) chloride affords the [(dpp-BIAN)H₂]·⁺[Cl]⁻ compound. The corresponding iodine derivative, [(dpp-BIAN)H₂]·⁺[I]⁻, was prepared by hydrolysis of the reaction products of the magnesium complex (dpp-BIAN)Mg(THF)₃ with tetraiodosilane. X-ray diffraction study demonstrated that the [(dpp-BIAN)H₂]^·+ radical cation in these compounds chelates the corresponding halide anion. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 436–440, March, 2006.     

Synthesis,structural characterization and substituent effects of two copper(II) complexes with benzaldehyde ortho-oxime ligands

Two new Cu(II) complexes, [Cu(L¹)₂] (1) and [Cu(L²)₂] (2) (HL¹ = (E)-3-bromo-5-chloro-2-hydroxy benzaldehyde O-methyl oxime; HL² = (E)-3-bromo-5-chloro-2-hydroxy benzaldehyde O-ethyl oxime), have been synthesized and characterized by physicochemical and spectroscopic methods. X-ray crystallographic analyses show that complexes 1 and 2 have similar structures, consisting of one Cu(II) atom and two L⁻ units. In both complexes, the Cu(II) atom, lying on an inversion center, is four-coordinated in a trans-CuN₂O₂ square-planar geometry by two phenolate O and two oxime N atoms from two symmetry-related N,O-bidentate oxime ligands. Moreover, both complexes form an infinite three-dimensional supramolecular structure involving intermolecular C–H···Br hydrogen bonds and π···π stacking interactions between the metal chelate rings and aromatic rings. Substituent effects in the two complexes are discussed.     

Synthesis and properties of bis(biphenyl)chromium(<Emphasis Type="SmallCaps">i</Emphasis>) 1,4-di(2-cyanoisopropyl)-1,4-dihydrofulleride and 1-(2-cyanoisopropyl)-1,2-dihydrofullerene

Radical-ion salts bis(biphenyl)chromium(i) 1,4-di(2-cyanoisopropyl)-1,4-dihydrofulleride [(Ph₂)₂Cr]^+·[1,4-(CMe₂CN)₂C₆₀]^−· and bis(biphenyl)chromium(i) 1-(2-cyanoisopropyl)-1,2-dihydrofulleride [(Ph₂)₂Cr]^+·[1,2-(CMe₂CN)(H)C₆₀]^−·, the salt bis(biphenyl)chromium(i) (2-cyanoisopropyl)fulleride [(Ph₂)₂Cr]^+·[(CMe₂CN)C₆₀]⁻, and neutral 1-(2-cyanoisopropyl)-1,2-dihydrofullerene 1,2-(CMe₂CN)(H)C₆₀ have been synthesized for the first time. The compounds [(Ph₂)₂Cr]^+·[1,4-(CMe₂CN)₂C₆₀]^−· and [(Ph₂)₂Cr]^+·[1,2-(CMe₂CN)(H)C₆₀]^−· decompose in THF to form [(Ph₂)₂Cr]^+·[(CMe₂CN)C₆₀]⁻, whose protonation affords 1,2-(CMe₂CN)(H)C₆₀. 1,4-Di(2-cyanoisopropyl)-1,4-dihydrofullerene 1,4-(CMe₂CN)₂C₆₀ and 1,2-(CMe₂CN)(H)C₆₀ are stable in vacuo up to 513 K. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1935–1939, September, 2008.     

Syntheses, electrochemical and spectroelectrochemical properties of novel ball-type and mononuclear Co(II) phthalocyanines substituted at the peripheral and non-peripheral positions with binaphthol groups

Mononuclear cobalt phthalocyanine (CoPc) substituted at the non-peripheral 8 and peripheral positions 9 with 1,1′-binaphthyl-8,8′-diol and ball-type dinuclear Co₂Pc₂ substituted at the non-peripheral 10 and peripheral 11 positions with the same substituent are reported. The complexes with 1,1′-binaphthol-bridges were prepared from the corresponding phthalonitriles 4-7. The effects of the position of substituent on spectral, electrochemical and spectroelectrochemical properties of these complexes were also explored. The mononuclear complexes 8 and 9 exhibited one metal reduction, one ring reduction and one ring oxidation. The redox properties of the ball-type complexes 10 and 11 exhibited two reduction processes assigned to [(Co^IPc⁻²)₂]²⁻/[(Co^IPc⁻³)₂]⁴⁻ (I), (Co^IIPc⁻²)₂/[(Co^IPc⁻²)₂]²⁻ (II) and one oxidation process assigned to [(Co^IIIPc⁻²)₂]²⁺/Co^IIPc⁻²)₂ (III). The ball-type complexes are much easier to oxidize and more difficult to reduce than the corresponding monomers 8 and 9.     

Structure of Dibenzocrown Ethers and their H-bonded Adducts. 3. Isolation of Oxonium Ions by Biphenyl-20-crown-6 and [1.5]Dibenzo-18-Crown-6 in Complexes with [NbF6]− and [TaF6]−

The reaction of Nb₂O₅ and Ta₂O₅ with an aqueous solution of hydrofluoric acid, HF in the presence of biphenyl-20-crown-6 (BP20C6, L¹) or [1.5]dibenzo-18-crown-6 ([1.5]DB18C6, L²) results in the complexes [L¹·(H₃O)][NbF₆] (1), [L¹ (H₃O)][TaF₆] (2), [2L²·(H₇O₃)][NbF₆] (3) and [2L²·(H₇O₃)][TaF₆] (4). Complexes 1–4 were identified by the elemental and X-ray structural analysis and IR spectroscopy. Complexes 1 and 2 are isostructural, with the H₃O⁺ oxonium ion embedded in one crown molecule via OH···O hydrogen bonds. Complexes 3 and 4 represent the supramolecular isomers distinctive by the crown conformations and crystal packing, with the (H₇O₃)⁺ cation enclosed in the cage of two crown molecules. Being poor H-bond acceptors, NbF₆⁻ and TaF₆⁻ anions do not compete with the crown oxygen atoms for the oxonium hydrogen atoms, but are involved in the numerous C–H···F short contacts responsible for the extended supramolecular architectures in all cases. A change of crown ethers’ conformation in complexes 1–4 and a correlation between the degree of proton hydration and an accessibility of the crown ether oxygen atoms is observed. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Fullerene complexes with bis(η6-hexamethylbenzene)chromium, hexamethylbenzene, and hexaethylbenzene

The [60]fulleride of bis(η-hexamethylbenzene)chromium(I) [(η⁶-C₆Me₆)₂Cr]^⋅+[C₆₀]^⋅−, and the complexes C₆₀·C₆Me₆ and C₆₀·C₆Et₆ were synthesized. Thermal decomposition of [(η⁶-C₆Me₆)₂Cr]^⋅+[C₆₀]^⋅− was studied. The molecular structures of C₆₀·C₆Me₆ and C₆₀·C₆Et₆ were determined. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 220—224, February, 2006.     

Synthesis,characterization, and prohibitive action on free radical O<Stack><Subscript>2</Subscript><Superscript>−·</Superscript></Stack> of β-phenylalanine schiff base binuclear complexes

A new Schiff base ligand as salt (KL) was synthesized using potassium salt of DL-β-phenylalanine and 2-hydroxy-1-naphthaldehyde. Two binuclear complexes of this ligand, [M₂L₂(CH₃COO)₂] (M = Cu(II), Ni(II)) have been synthesized and characterized by elemental analyses, IR, UV spectra, and molar conductance. Their prohibitive action on the superoxide anion free radical (O₂^−·) was estimated by the NBT illumination deoxidizing method (Methionine-lactoflavin illumination method). The results suggested that the ligand and its complexes had the prohibitive action on O₂^−·. The text was submitted by the authors in English.     

Thermodynamic characteristics of bis(η6-ethylbenzene)chromium fulleride

The temperature dependence of heat capacity of crystalline bis(η⁶-ethylbenzene)chromium fulleride [(η⁶-EtPh)₂Cr]^·+ [C₆₀]^·− was studied in adiabatic vacuum calorimeter in the range of 6.7 to 344 K with an error of ±0.3%. Dependence of the parameters of EPR signal of bis(η⁶-ethylbenzene)chromium fulleride on temperature was studied by electron paramagnetic resonance (EPR) in the range of 120 to 290 K. In the range of 204 to 246 K, upon heating, reversible endothermic transformation was recorded, which is caused by the dissociation of dimer (C₆₀⁻)₂ and formation of fulleride [(η⁶-EtPh)₂Cr]^·+ [C₆₀]^·−; its standard thermodynamic parameters were estimated and analyzed. Standard thermodynamic functions were calculated by the experimental data obtained: heat capacity, enthalpy, entropy, and Gibbs function of fulleride dimmer in the range of T → 0 to 204 K and monomer complex [(η⁶-EtPh)₂Cr]^·+ [C₆₀]^·− in the range of 246 to 344 K. Standard thermodynamic properties of fulleride under study, fullerides studied earlier, and fullerite C₆₀ were compared.     

Oxidation of electron deficient olefins using a copper(II) complex based on a bis-benzimidazole diamide ligand

New bis-benzimidazole based diamide ligands N, N′-bis(2-methyl benzimidazolyl)-benzene-1,3-dicarboxamide [GBBA] and N-Octyl-N, N′-bis(2-methyl benzimidazolyl)-benzene- 1,3-dicarboxamide [O-GBBA] have been synthesized and utilized to prepare Cu(II) complexes of general composition [Cu(GBBA)X ₂] · nH₂O and [Cu(O-GBBA)X₂] · n H₂O, where X is an exogenous anionic ligand (X = Cl⁻, NO₃⁻, SCN⁻). The oxidation of electron deficient olefins has been investigated using [Cu(O-GBBA)X₂] · nH₂O as catalyst and TBHP as an alternate source of oxygen. The respective ketonic products have been isolated and characterized by ¹H-NMR. The complex [Cu(GBBA)(NO₃)₂] · 4H₂O has been characterized structurally. It crystallizes in a monoclinic space group C2/c. Low temperature EPR spectra have been obtained for the complexes that shows g_II > g_I > 2.0024, indicating a tetragonal geometry in the solution state. The complexes display a quasi reversible redox wave due to the Cu(II)/Cu(I) reduction process. The E_1/2 values shift anodically as NO₃⁻ < SCN⁻ < Cl⁻.     

Polyoxomolybdates functionalized with aminomethylene phosphonate

A new organic-inorganic hybrid Strandberg-type polyoxomolybdate derivative [(n-C₄H₉)₄N]₂[(NH₂CH₂PO₃)₂Mo₅O₁₅] · (CH₃NHCH₃)₂ · H₂O (I) has been synthesized and structurally characterized by elemental analysis, IR spectrum, UV spectrum, TG analysis, cyclic voltammetry, and single-crystal X-ray diffraction. The hybrid polyoxoanion [(NH₂CH₂PO₃)₂Mo₅O₁₅]²⁻ consists of a ring-shaped {Mo₅O₂₁} cluster with two [NH₂CH₂PO₃]⁻ groups incorporating into the opposite sides of the ring. The UV spectrum studied at different times reveals that I remains stable in CH₃CN-H₂O solvents (volume ratio = 1 : 2) for one day, and the electrochemical measurement indicates that I can exist in a pH range of 4.12–4.72.     

Reactivity of triangular oxalate cluster complexes [M<Subscript>3</Subscript>Q<Subscript>7</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>3</Subscript>]<Superscript>2−</Superscript> (M = Mo or W; Q = S or Se)

The reactions of the oxalate complexes [M₃Q₇(C₂O₄)₃]²⁻ (M = Mo or W; Q = S or Se) with Mn^II, Co^II, Ni^II, and Cu^II aqua and ethylenediamine complexes in aqueous and aqueous ethanolic solutions were studied. The previously unknown heterometallic complexes [Mo₃Se₇(C₂O₄)₃Ni(H₂O)₅]·3.5H₂O (1) and K₃{[Cu(en)₂H₂O]([Mo₃S₇(ox)₃]₂Br)}·5.5H₂O (2) were synthesized. In these complexes, the oxalate clusters serve as monodentate ligands. The K(H₂en)₂[W₃S₇(C₂O₄)₃]₂Br·4H₂O salt (3) was isolated from solutions containing Co^II, Ni^II, or Cu^II aqua complexes and ethylenediamine. The reaction of [Mo₃Se₇(C₂O₄)₃]²⁻ with HBr produced the bromide complex [Mo₃Se₇Br₆]²⁻, which was isolated as (Bu₄N)₂[Mo₃Se₇Br₆] (4). Complexes 1–3 were characterized by X-ray diffraction, IR spectra, and elemental analysis. The formation of 4 was detected by electrospray mass spectrometry. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1645–1649, September, 2007.     

Synthesis,structures and electrochemical properties of four organic–inorganic hybrid polyoxometalates constructed from polyoxotungstate clusters and transition metal complexes

Four novel organic–inorganic hybrid compounds [Cu₅ ^I(4,4′-bpy)₃(2,2′-bpy)₄][BW₁₂O₄₀] · H₂O (1), [Ni_0.5(2,2′-bpy)_1.25][Ni(2,2′-bpy)₃][Ni(2,2′-bpy)₂(H₂O)(SiW₁₁^VIW^VO₄₀)] · 0.5H₂O (2), [H₂bpy]₂[Zn(2,2′-bpy)₃]₂[Si₂W₁₈O₆₂] · 1.5H₂O (3) and [Cu^II(2,2′-bpy)₂]₂[SiW₁₂O₄₀] · 2H₂O (4) (2,2′-bpy = 2,2′-bipyridine, 4,4′-bpy = 4,4′-bipyridine) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis, electrochemical measurements and single-crystal X-ray diffraction. Compound (1) is a novel [BW₁₂O₄₀]⁵⁻ polyoxoanion bisupported by copper(I) coordination cations with mixed 2,2′-bpy and 4,4′-bpy ligands. Compound (2) is constructed from the [SiW₁₁^VIW^VO₄₀]⁵⁻ polyoxoanions supported by [Ni(2,2′–bpy)₂]²⁺. Compound (3) is composed of a novel [Si₂W₁₈O₆₂]⁸⁻ cluster and [Zn(2,2′–bpy)₃]²⁺ complexes, which held together into a three-dimensional (3D) supramolecular network through hydrogen-bonding interactions. Compound (4) shows a 2D layer framework constructed from a bisupporting Keggin polyoxoanion cluster and [Cu(2,2′–bpy)₂]²⁺ coordination polymer fragments, resulting in 3D networks via supramolecular interactions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

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.     

A series of trinuclear sandwich-like cyanide-bridged iron(III)-manganese(II) complexes: synthesis,crystal structures,and magnetic properties

Four pyridinecarboxamide iron dicyanide building blocks and one Mn(III) compound have been employed to assemble cyanide-bridged heterometallic complexes, resulting in a series of trinuclear cyanide-bridged Fe^III–Mn^II complexes: {[Mn(DMF)₂ (MeOH)₂][Fe(bpb)(CN)₂]₂}·2DMF (1), {[Mn(MeOH)₄][Fe(bpmb)(CN)₂]₂}·2MeOH·2H₂O (2), {[Mn(MeOH)₄][Fe(bpdmb)(CN)₂]₂}·2MeOH·2H₂O (3) and {[Mn(MeOH)₄][Fe(bpClb)(CN)₂]₂}·4MeOH (4) (bpb²⁻ = 1,2-bis(pyridine-2-carboxamido)benzenate, bpmb²⁻ = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpdmb²⁻ = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate, bpClb²⁻ = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate). Single-crystal X-ray diffraction analysis shows their similar sandwich-like structures, in which the two cyanide-containing building blocks act as monodentate ligands through one of their two cyanide groups to coordinate the Mn(II) center. Investigation of the magnetic properties of these complexes reveals antiferromagnetic coupling between the neighboring Fe(III) and Mn(II) centers through the bridging cyanide group. A best fit to the magnetic susceptibilities of complexes 1 and 3 gave the magnetic coupling constants J = −1.59(2) and −1.32(4) cm⁻¹, respectively.     

Equilibrium study on the reactions of boric acid with some cis -diaqua CrIII-complexes

Substitution inertcis-diaqua Cr^III complexes: cis-[(L^x−)Cr^III(H₂O)₂]^(3−x)+ derived from N-donor ligands (L^x−) viz., bipyridine and 1,10-phenanthroline (x = 0) and N,O-donor ligands viz., nitrilotriacetate and anthranilate N,N-diacetate (x = 3) titrate as diprotic acids in aqueous solution and enhance the acidity of otherwise weakly acidic boric acid (H₃BO₃) producing mononuclear and binuclear mixed ligand Cr^III-borate complexes: [(L)Cr(H₂BO₄)]^x− and [(L)Cr(BO₄)Cr(L)]^(1−2x)+ respectively through coordination of the H₂O and/or OH⁻ ligands, cis-coordinated in the Cr^III-complexes on the electron deficient B^III-atom in H₃BO₃ with release of protons. Deprotonation of the parent Cr^III-complexes and their reactions with H₃BO₃ have been investigated by potentiometric method in aqueous solution,I = 0.1 mol dm⁻³ (NaNO₃) at 25 ±0.1°C. The equilibrium constants have been evaluated by computerized methods and the tentative stoichiometry of the reactions have been worked out on the basis of the speciation curves     

Synthesis and characterization of two inorganic–organic hybrid polyoxometalates bridged by Keggin-type building blocks and copper(II) organonitrogen complexes

Two new inorganic–organic hybrid compounds, namely [Cu(dab)₂]₂[α-SiW₁₂O₄₀]·H₂O (dab = 1,2-diaminobenzene) and [Cu(dafo)₃]₂[Cu(dafo)₂(H₂O)₂][α-PMo₁₂O₄₀]₂·4H₂O (dafo = 4,5-diaza- fluorene-9-one) have been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction. [Cu(dab)₂]₂[α-SiW₁₂O₄₀]·H₂O exhibits an alternating 2D ladder-like structure built of [α-SiW₁₂O₄₀]⁴⁻ and [Cu(L)₂]²⁺ units. As the inorganic building block, the Keggin-type polyoxoanion [α-SiW₁₂O₄₀]⁴⁻ is linked to two metal–organic complexes [Cu(dab)₂]²⁺ through different kinds of oxygen atoms (terminal and bridging). [Cu(dafo)₃]₂[Cu(dafo)₂(H₂O)₂][α-PMo₁₂O₄₀]₂·4H₂O shows an extended 3D supramolecular network via hydrogen bonding. Both complexes were characterized by physico-chemical and spectroscopic methods.     

DNA-binding and nuclease activity of 1,10-phenanthroline-based thiocyanato,acetato, azido and benzoato bridged dinuclear copper(II) complexes

The mononuclear Cu(II) complex [Cu(phen)(H₂O)(NO₃)₂] (1), obtained by the reaction of 1,10-phenanthroline with Cu(NO₃)₂·3H₂O in methanol solution, reacts with anionic ligands SCN⁻, AcO⁻, N₃ ⁻ and PhCO₂ ⁻ in MeOH solution to form the stable binuclear complexes [Cu₂(H₂O)₂(phen)₂(μ-X)₂]₂ (NO₃)₂, where X = SCN⁻ (2), AcO⁻ (3), N₃ ⁻ (4) or PhCO₂ ⁻(5). The molecular structure of complex 3 was determined by single-crystal X-ray diffraction studies. These complexes were characterized by electronic, IR, ESR, magnetic moments and conductivity measurements. The electrochemical behaviour of the complexes was investigated by cyclic voltammetry. The interactions of these complexes with calf thymus DNA have been investigated using absorption spectrophotometry. Their DNA cleavage activity was studied on double-stranded pBR322 plasmid DNA using gel electrophoresis experiments in the absence and presence of H₂O₂ as oxidant.     

The thermodynamic properties of bis(η<Superscript>6</Superscript>-ethoxybenzene)chromium fulleride from <Emphasis Type="Italic">T</Emphasis> → 0 to 340 K

The temperature dependence of the heat capacity of crystalline bis-(η⁶-ethoxybenzene)chromium fulleride [(η⁶-(EtOPh))₂Cr]^·+[C₆₀]^·− was studied for the first time by adiabatic vacuum calorimetry over the temperature range 6–340 K with errors of ±0.2%. The temperature dependence of the EPR signal parameters of bis-(η⁶-ethoxybenzene)chromium fulleride was studied for the first time from 120 to 340 K. A reversible endothermic transformation was observed between 160 and 250 K during heating; it was caused by the dissociation of the [(C₆₀)₂]²⁻ dimer and the formation of the [(η⁶-(EtOPh))₂Cr]^·+[C₆₀]^·− fulleride; its standard thermodynamic characteristics were estimated and analyzed. The experimental data were used to calculate the standard thermodynamic functions, including the heat capacity, enthalpy, entropy, and Gibbs function of the fulleride dimer from T → 0 to 160 K and the [(η⁶-(EtOPh))₂Cr]^·+[C₆₀]^·− monomeric complex over the temperature range 250–340 K. The standard thermodynamic properties of the fulleride studied, fullerides studied earlier, and fullerite C₆₀ were compared.     

An ion crystal based on silver double helicates and Keggin polyanions

An ion crystal [Ag₂L₂][(n-C₄H₉)₄N][PMo₁₂O₄₀] · H₂O · 0.5CH₃OH · 0.25 DMF (I) (DMF is N,N-dimethylformamide) has been synthesized by the complexation of metal double helix and Keggin polyanions in a DMF-CH₃ OH solution and structurally characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. In compound I [PMo₁₂O₄₀]³⁻ anions and [(n-C₄H₉)₄N]⁺ ions alternately arrange themselves in a special order in consistence with that of [Ag₂L₂]²⁺ metal helicates based on π-π stacking interactions, yielding a packing of complex cations and Keggin anions.