Synthesis and spectral properties of titanium(iv) polynuclear hydroxo complexes stabilized in solution by the [PW11O39]7− heteropolyanion

Unsaturated heteropolyanions (HPA) [PW₁₁O₃₉]⁷⁻ stabilize Ti^IV hydroxo complexes in aqueous solutions (Ti: PW₁₁ [PW₁₁O₃₉]⁷⁻⪯12, pH 1–3). Spectral studies (optical,¹⁷O and³¹P NMR, and IR spectra) and studies by the differential dissolution method demonstrated that Ti^IV hydroxo complexes are stabilized through interactions of polynuclear Ti^IV hydroxo cations with heteropolyanions [PW₁₁TiO₄₀ ⁵⁻ formed. Depending on the reaction conditions, hydroxo cations Ti _n−1O _x H _y ^m+ either add to oxygen atoms of the W−O−Ti bridges of the heteropolyanions to form the complex [PW₁₁TiO₄₀·Ti _n−1O _x H _y ] ^k− (at [HPA]=0.01 mol L⁻¹) or interact with Ti^IV of the heteropolyanions through the terminal o atom to give the polynuclear complexes [PW₁₁O₃₉Ti−O−Ti _n−1O _x H _y ]^q− (at [HPA]=0.2 mol L⁻¹). When the complexes of the first type were treated with H₂O₂, Ti^IV ions added peroxo groups. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 914–920, May, 1997.     

Epoxidation of cycloolefins with hydrogen peroxide in the presence of heteropoly acids combined with phase transfer catalyst

Oxidation of cycloolefins (cyclohexene, cyclooctene, and cyclododecene) with a 30% solution of hydrogen peroxide at 65 °C in the presence of heteropoly acids (HPA) H₃PW_12–x Mo _x O₄₀ (x = 0—12), which are precursors of active peroxo complexes, and phase transfer catalysts Q⁺Cl^–, where Q⁺ is the quaternary ammonium cation containing C₄—C₁₈ alkyl groups or [C₅H₅NC₁₆H₃₃]⁺, was studied. The catalytic activity decreases in the HPA series: H₃PW₁₂O₄₀ > H₃PW₉Mo₃O₄₀ > H₃PW₆Mo₆O₄₀ > H₃PW₃Mo₉O₄₀ > H₃PMo₁₂O₄₀. The state of the H₃PW₁₂O₄₀—I₂I₂ system was studied using UV, IR, and ³¹P NMR spectroscopies with variation of the [H₂O₂] : [HPA] ratio from 2 to 200 during cyclohexene epoxidation. Despite different catalytic precursors, the reaction proceeds through the same peroxo complex.     

Titanium(IV) polynuclear hydroxo complexes stabilized in solution by [PW11O39]7? heteropolyanion

[PW₁₁O₃₉]^7– heteropolyanion (HPA) stabilizes Ti(IV) in aqueous solution at Ti:PW₁₁ ratios from 1 to 12 and pH 1–3. Ti(IV) is completely precipitated under these conditions in the absence of HPA. Differential dissolution phase analysis, optical, IR,³¹P and¹⁷O NMR spectra show that one Ti(IV) ion is incorporated into the Keggin lattice. The other ions, most probably, are located on the HPA surface in the form of oligomeric hydroxo fragments: [PW₁₁Ti^IVO₄₀·Ti_n–1 ^IVO_xH_y]^k–. Both types of Ti(IV) ions bind peroxo groups on interaction of the complex with H₂O₂.     

Structure and properties of H<Subscript>8</Subscript>(PW<Subscript>11</Subscript>TiO<Subscript>39</Subscript>)<Subscript>2</Subscript>O heteropoly acid

Heteropoly acid (HPA) H₈(PW₁₁TiO₃₉)₂O·xH₂O (I) is synthesized by three different ways and studied by chemical analysis, potentiometric titration, mass-spectrometry, IR, ³¹P, ¹⁸³W, and ¹⁷O NMR spectroscopy, thermogravimetry, and transmission electron microscopy. Anion I consists of two subparticles of the Keggin structure bridged by Ti-O-Ti. The dimeric anion exists in HPA aqueous solutions at [I] > 0.02 M. At pH > 0.6 it splits to a [PW₁₁TiO₄₀]⁵⁻ monomer stable up to pH ∼ 6. When heated (150–400)°C, I splits into H₃PW₁₂O₄₀ and, apparently, H₃PW₁₀Ti₂O₃₈ without phase separation. Thermolysis products are soluble and when dissolved in water turn again into I. Complete decomposition of I to oxides occurs at ∼450°C.     

Membrane separation of ions for the preparation of pure solutions of heteropolycompounds

Reverse osmosis was used for the separation of various types of heteropolyanions (HPA): [PW₁₁O₃₉M(H₂O)] ^k– (M = Co^II, Fe^III, Cr^III), [(PW₁₁O₃₉Fe)₂O]^10– , and [PW₁₁O₃₉ · Fe _n O _x H _y ] ^p– from contaminant ions NO₃ ^– and Na⁺ that are usually introduced into the solution in the synthesis of HPA.Translated fromIzvestiya Akodemii Nauk. Seriya Khimicheskaya, No. 4, pp. 1009–1011, April, 1996.     

Oxidation of methyl phenyl sulfide with hydrogen peroxide catalyzed by Ti(IV)-substituted heteropolytungstate

Alkylammonium salts of Ti(IV)-substituted heteropolytungstate, PW₁₁TiO ₁₀ ⁵⁻ , catalyze the oxidation of methyl phenyl sulfide with hydrogen peroxide. The yield of the corresponding sulfoxide and sulfone is practically quantitative. A³¹P NMR study confirms the formation and reactivity of the PW₁₁O₃₉TiO ₂ ⁵⁻ peroxo complex in organic media.     

A sandwich-type POM containing mixed cations: synthesis,thermal performance and proton-conducting properties

A new sandwich-type polyoxometalate, Na₅H[N(CH₃)₄]₂[Co(C₃N₂H₄)₂(H₂O)₄][Co₄(H₂O)₂(PW₉O₃₄)₂]·21H₂O (1), has been synthesized. 1 is composed of a Weakley-type polyanion, [Co₄₍H₂O)₂(PW₉O₃₄)₂]^10?, four kinds of cations (five Na⁺, two [N(CH₃)₄]⁺, one [Co(C₃N₂H₄)₂(H₂O)₄]²⁺, and one H⁺), and 21 crystalline H₂O molecules. The surface oxygen of the polyanion in 1, the crystalline water, and coordinated water molecules make an extended 3-D hydrogen-bonding network. Alternating current (AC) impedance experiments of 1 reveal good proton conductivity for 1 of 5.03 × 10^??4 S cm^?1 at 25 °C under 98% relative humidity (RH). Activation energy of 1 calculated from Arrhenius plots is 0.358 eV, indicating Grotthuss mechanism is dominant in the proton transfer. Thermal decomposition behavior of 1 was examined by thermogravimetry/mass spectrometry (TG/MS) measurements.     

Catalytic effects of [Ag(H2O)(H3PW11O39)]3− on a TiO2 anode for water oxidation

A [H₃Ag^I(H₂O)PW₁₁O₃₉]^3?-TiO₂/ITO electrode was fabricated by immobilizing a molecular polyoxometalate-based water oxidation catalyst, [H₃Ag^I(H₂O)PW₁₁O₃₉]^3? (AgPW₁₁), on a TiO₂ electrode. The resulting electrode was characterized by X-ray powder diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Linear sweep voltammetry, chronoamperometry, and electrochemical impedance measurements were performed in aqueous Na₂SO₄ solution (0.1 mol L^?1). We found that a higher applied voltage led to better catalytic performance by AgPW₁₁. The AgPW₁₁-TiO₂/ITO electrode gave currents respectively 10 and 2.5 times as high as those of the TiO₂/ITO and AgNO₃-TiO₂/ITO electrodes at an applied voltage of 1.5 V vs Ag/AgCl. This result was attributed to the lower charge transfer resistance at the electrode-electrolyte interface for the AgPW₁₁-TiO₂/ITO electrode. Under illumination, the photocurrent was not obviously enhanced although the total anode current increased. The AgPW₁₁-TiO₂/ITO electrode was relatively stable. Cyclic voltammetry of AgPW₁₁ was performed in phosphate buffer solution (0.1 mol L^?1). We found that oxidation of AgPW₁₁ was a quasi-reversible process related to one-electron and one-proton transfer. We deduced that disproportionation of the oxidized [H₂Ag^II(H₂O)PW₁₁O₃₉]^3? might have occurred and the resulting [H₃Ag^IIIOPW₁₁O₃₉]^3? oxidized water to O₂.     

Syntheses,crystal structures,and magnetic properties of the banana-shaped tungstophosphates: [M6(H2O)2(PW9O34)2(PW6O26)]17− (MII=NiII,CoII)

Two new banana-shaped tungstophosphates [M₆(H₂O)₂(PW₉O₃₄)₂(PW₆O₂₆)]^{17 ?} (M^II?=?Ni^II, Co^II) incorporating two types of lacunary polyoxometalate units have been synthesized in aqueous solution and characterized by elemental analyses, IR, and UV spectra, and single-crystal X-ray diffraction. Structural analyses show that Na₆H₁₁[Ni₆(H₂O)₂(PW₉O₃₄)₂(PW₆O₂₆)]?·?32H₂O (1) and Na₇H₁₀[Co₆(H₂O)₂(PW₉O₃₄)₂(PW₆O₂₆)]?· 31H₂O (2) are generated from two tri-M^II substituted B-α-[(MOH₂)M₂PW₉O₃₄] Keggin units connected by a hexavacant [PW₆O₂₆]^11? Keggin fragment, leading to the M^II-containing banana-shaped tungstophosphates. Magnetic properties of 2 show decrease of the molar magnetic susceptibility at higher temperatures results from spin-orbit coupling of Co^II and antiferromagnetic interactions whereas the maximum at the lower temperatures is indicative of the ferromagnetic interactions within the trinuclear Co^II spin cluster in the sandwich belt.     

Electrochemical characterization of glassy carbon electrodes modified with hybrid inorganic-organic single-layer of α-Keggin type polyoxotungstates

It has been demonstrated, for the first time, that an adsorbed single-layer of the hybrid salts (TBA)₄H₃PW₁₁O₃₉, (TBA)₄PW₁₁Fe(H₂O)O₃₉, (TBA)₄PW₁₁Mn(H₂O)O₃₉ and (TBA)₄HPW₁₁Co(H₂O)O₃₉ can be fabricated on the surface of a glassy carbon electrode by the droplet evaporation methodology. These chemically modified electrodes were stable and their preparation was reproducible and easy to perform. The electrochemical features of the immobilized polyanions were different from those of the corresponding soluble species, namely in what concerns the peak potential values. The effect of the scan rate and of pH on the voltammetric features led to the conclusion that the first W reduction process for all immobilized polyanions was diffusion-controlled. For TBA-PW₁₁, TBA-PW₁₁Fe and TBA-PW₁₁Co the two-electron reductions at the first W waves are accompanied by the uptake of protons (2 H⁺ for the PW₁₁ anion and 4 H⁺ for the Fe-substituted and Co-substituted species). For the PW₁₁Mn-modified electrode, the reduction at the first W wave was a 1 e/2 H⁺ process. Additionally, the results obtained in the presence of Na₂SO₄ in the solution highlighted the role of the ions in the supporting electrolyte in the redox features of the immobilized hybrid phosphotungstates.     

Esterification of n-Butanol with Acetic Acid in the Presence of Heteropoly Acids with Different Structures and Compositions

The esterification reaction of n-butanol with acetic acid ([BuOH] : [HOAc] = 1 : 15 mol/mol; 55°C, 5% H₂O) was studied in the presence of tungsten heteropoly acids of the Keggin (H₃PW₁₂O₄₀, H₄SiW₁₂O₄₀, H₅PW₁₁TiO₄₀, H₅PW₁₁ZrO₄₀, and H₃PW₁₁ThO₃₉) and Dawson structure (-H₆P₂W₁₈O₆₂, H₆P₂W₂₁O₇₁(H₂O)₃, H₆As₂W₂₁O₆₉(H₂O), and H₂₁B₃W₃₉O₁₃₂). The reaction orders with respect to H₆P₂W₂₁O₇₁(H₂O)₃, H₃PW₁₂O₄₀, and H₆P₂W₁₈O₆₉are equal to 0.78, 1.00, and 0.97, respectively. It was found that the reaction rate depends on the acidity, as well as on the structure and composition of heteropoly acids. The H₂₁B₃W₃₉O₁₃₂heteropoly acid is most active, whereas the Keggin-structure heteropoly acids exhibit the lowest activities. Of the Keggin structure heteropoly acids, H₅PW₁₁ZrO₄₀exhibits the highest activity because of the presence of a Lewis acid site in its structure.     

Synthesis,structure and electrochemical properties of a polyoxometalate-templated compound with 2D twofold interpenetrating network

A new Keggin-type polyoxometalate-based compound {[Cu₂(L)₄(H₂O)₄](PW₁₁^VIW^VO₄₀)}·16H₂O (1) constructed from PW₁₁^VIW^VO₄₀ ⁴⁻, N,N′-bis(4-pyridylformyl) piperazine (L) and Cu(II) has been hydrothermally synthesized and structurally characterized by elemental analyses, IR and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis reveals that the semi-rigid piperazine-based ligands L coordinate to the Cu(II) atoms to constitute a two dimensional coordination network. The 2D (4, 4) cationic layers are stacked together in a perpendicular mode, resulting in the formation of twofold interpenetrating frameworks with large cavities. The PW₁₂ anions reside in the large cubic-like cavities, serving as non-coordinating templates. The compound 1 displays good electrocatalytic activity toward the reduction of nitrite in 1 M H₂SO₄ aqueous solution.     

Synthesis and structure of 9-hydroxy-1,2-dicarba-closo-dodecaborane(11)

The oxidation of 1,2-C₂B₁₀H₁₂ (1) with 100% nitric acid was studied in two solvents (CH₂C1₂ and CCl₄). Under the action of superacid (CF3SO3H), the compound 9-HO-1,2-C₂B₁₀H₁₁ (2) gives the onium cation 9-H₂O⁺-1,2-C₂B₁₀H₁₁ involved in the salt [9-H₂O⁺-1,2-C₂B₁₀H_n]-CF₃SO₃^?, as demonstrated by ^uB NMR spectroscopy. The experimental and simulated ^uB NMR spectra of the cation 9-H₂O⁺-1,2-C₂B₁₀H₁₁ are in satisfactory agreement with each other. In the presence of a base, compound 2 is transferred from an ethereal solution to an aqueous alkaline solution giving the anion 9-O^?- 1,2-C₂B₁₀H₁₁. The structure of compound 2 was confirmed by ¹H, ¹¹B, ¹¹B¹H, ¹¹B-¹¹B COSY NMR spectroscopy, IR spectroscopy, and gas chromatography mass spectrometry and was additionally established by X-ray diffraction.

     

Efficient epoxidation of electron-deficient alkenes with hydrogen peroxide catalyzed by [γ-PW10O38V2(μ-OH)2]3-

A divanadium‐substituted phosphotungstate, [γ‐PW₁₀O₃₈V₂(μ‐OH)₂]^3? ( I ), showed the highest catalytic activity for the H₂O₂‐based epoxidation of allyl acetate among vanadium and tungsten complexes with a turnover number of 210. In the presence of I , various kinds of electron‐deficient alkenes with acetate, ether, carbonyl, and chloro groups at the allylic positions could chemoselectively be oxidized to the corresponding epoxides in high yields with only an equimolar amount of H₂O₂ with respect to the substrates. Even acrylonitrile and methacrylonitrile could be epoxidized without formation of the corresponding amides. In addition, I could rapidly (≤10 min) catalyze epoxidation of various kinds of terminal, internal, and cyclic alkenes with H₂O₂ under the stoichiometric conditions. The mechanistic, spectroscopic, and kinetic studies showed that the I ‐catalyzed epoxidation consists of the following three steps: 1) The reaction of I with H₂O₂ leads to reversible formation of a hydroperoxo species [γ‐PW₁₀O₃₈V₂(μ‐OH)(μ‐OOH)]^3? ( II ), 2) the successive dehydration of II forms an active oxygen species with a peroxo group [γ‐PW₁₀O₃₈V₂(μ‐η²:η²‐O₂)]^3? ( III ), and 3) III reacts with alkene to form the corresponding epoxide. The kinetic studies showed that the present epoxidation proceeds via III . Catalytic activities of divanadium‐substituted polyoxotungstates for epoxidation with H₂O₂ were dependent on the different kinds of the heteroatoms (i.e., Si or P) in the catalyst and I was more active than [γ‐SiW₁₀O₃₈V₂(μ‐OH)₂]^4?. On the basis of the kinetic, spectroscopic, and computational results, including those of [γ‐SiW₁₀O₃₈V₂(μ‐OH)₂]^4?, the acidity of the hydroperoxo species in II would play an important role in the dehydration reactivity (i.e., k₃). The largest k₃ value of I leads to a significant increase in the catalytic activity of I under the more concentrated conditions.     

The Liquid Junction Potential in Potentiometric Titrations. IX. The Calculation of Potentials Across Liquid Junctions of the Type, AY|AY+BY z(B)+HY+ A y L, for Emf Cells where Strong or Weak Complexes are Formed, Respectively, at [Y−] = C mol⋅L−1, Constant and −log 10[H+]≤ 7

In the present part, potential functions are derived for the calculation of the total potential anomalies, Δ E _B and Δ E _H, for Emf cells where strong or weak complexes are formed, respectively. A weak or strong electrolyte is considered to be used as complexing agent (A _y L), respectively, at the experimental condition, [Y^?] = C mol?L^?1, constant. The cells have indicator electrodes reversible to B ^z(B)+ (cell B) and H⁺ ions (cell H), respectively. The system, HY–BY _z(B)-A _Y L-AY and the protolysis of the acids HL and H₂L in the ionic medium (A⁺, Y^?) are studied. Here, y = |z _L |. Moreover, some useful Emf titrations are suggested for the experimental determination of the slope functions SL(H, L^?), SL (H, L^2?) and SL(H, HL^?). The usefulness of the derived potential functions is established using the H⁺-acetate^? (CH₃COO^?) system as an example.     

Glycol modified titanosiloxane as molecular precursor for homogenous titania–silica material: synthesis and characterization

Ti(OPrⁱ)₄ reacts with HOSi(O^tBu)₃ in anhydrous benzene in 1:1 and 1:2 molar ratios to afford alkoxy titanosiloxane precursors, [Ti(OPrⁱ)₃{OSi(O^tBu)₃}] (A) and [Ti(OPrⁱ)₂{OSi(O^tBu)₃}₂] (B), respectively. Further reactions of (A) or (B) with glycols in 1:1 molar ratio afforded six complexes of the types [Ti(OPrⁱ)(O–G–O){OSi(O^tBu)₃}] (1A–3A) and [Ti(O–G–O){OSi(O^tBu)₃}₂] (1B–3B), respectively [where G = (CH₂)₂ (1A, 1B); (CH₂)₃ (2A, 2B) and {CH₂CH₂CH(CH₃)} (3A, 3B)]. Both (A) and (B) are liquids while all the other products are viscous liquids which get solidified on ageing. Cryoscopic molecular weight measurements of the fresh products indicate their monomeric nature. FAB mass studies of (A) and (B) also indicate monomeric nature. However, FAB mass spectra of the two representative solids (1A) and (2B) suggest dimeric behavior of the glycolato derivatives. (A) distills at 85 °C/5 mm while other products get decomposed even under reduced pressure. TG analyses of (A), (B), (1A), and (1B) suggest formation of titania–silica materials at 200 °C for (A) and (B) and 350 °C for (1A) and (1B). The products have been characterized by elemental analyses, FTIR and ¹H, ¹³C & ²⁹Si-NMR techniques. All these products are soluble in common organic solvents indicating a homogenous distribution of the components on the molecular scale. The Si/Ti ratio of the oxide may be controlled easily by the composition of the starting precursors. Hydrolysis of the glycol modified derivative, (1A) by the Sol–Gel technique affords the desired homogenous titania–silica material, TiO₂·SiO₂ in nano-size while, the precursor (A) yields a non-stiochiometric silica doped titania material. However, pyrolysis of (A) yields nano-sized crystallites of TiO₂·SiO₂. All these materials were characterized by FTIR, powder XRD patterns, SEM images, and EDX analyses.     

New members of the [Mn6/oxime] family and analogues with converging [Mn3] planes

The synthesis, structural, and magnetic characterization of five new members of the hexanuclear oximate [Mn^III₆] family are reported. All five clusters can be described with the general formula [Mn^III₆O₂(R-sao)₆(R′-CO₂)₂(sol)_x(H₂O)_y] (where R-saoH₂ = salicylaldoxime substituted at the oxime carbon with R = H, Me and Et; R′ = 1-naphthalene, 2-naphthalene, and 1-pyrene; sol = MeOH, EtOH, or MeCN; x = 0–4 and y = 0–4). More specifically, the reaction of Mn(ClO₄)₂·6H₂O with salicylaldoxime-like ligands and the appropriate carboxylic acid in alcoholic or MeCN solutions in the presence of base afforded complexes 1–5: [Mn₆O₂(Me-sao)₆(1-naphth-CO₂)₂(H₂O)(MeCN)]·4MeCN (1·4MeCN); [Mn₆O₂(Me-sao)₆(2-naphth-CO₂)₂(H₂O)(MeCN)]·3MeCN·0.1H₂O (2·3MeCN·0.1H₂O); [Mn₆O₂(Et-sao)₆(2-naphth-CO₂)₂(EtOH)₄(H₂O)₂] (3); [Mn₆O₂(Et-sao)₆(2-naphth-CO₂)₂(MeOH)₆] (4) and [Mn₆O₂(sao)₆(1-pyrene-CO₂)₂(H₂O)₂(EtOH)₂]·6EtOH (5·6EtOH). Clusters 3, 4, and 5 display the usual [Mn₆/oximate] structural motif consisting of two [Mn₃O] subunits bridged by two O_oximate atoms from two R-sao^2? ligands to form the hexanuclear complex in which the two triangular [Mn₃] units are parallel to each other. On the contrary, clusters 1 and 2 display a highly distorted stacking arrangement of the two [Mn₃] subunits resulting in two converging planes, forming a novel motif in the [Mn₆] family. Investigation of the magnetic properties for all complexes reveal dominant antiferromagnetic interactions for 1, 2, and 5, while 3 and 4 display dominant ferromagnetic interactions with a ground state of S = 12 for both clusters. Finally, 3 and 4 display single-molecule magnet behavior with U_eff = 63 and 36 K, respectively.     

Formation of nanoperiodic structures based on keggin and lacunar anions of phosphotungstic acid and cationic surfactants

Surface-active cations (A⁺) in an aqueous medium, at pH 1.0 with excess phosphotungstic acid, form compounds with the composition A₃[PW₁₂O₄₀]; but at pH 4.5, they form acid salts A_nH_7−n[PW₁₁O₃₉]·xH₂O that have a nanoperiodic structure. The structural parameters are greatly dependent on the nature of the surfactant and on the type of heteropolyion. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospect Nauki, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 4, pp. 250–256, July–August, 1998.     

Palladium(II), Copper(II), Iron(III), and Vanadium(V) Complexes with Heteropolyanion PW9O9–34: 31P, 183W, 51V NMR and IR Spectroscopy Studies

The formation of Pd(II)-containing and mixed Pd(II),Cu(II), Pd(II),Fe(III), and Pd(II),V(V) complexes with heteropolyanion PW₉O^9– ₃₄was studied using ³¹P, ¹⁸³W, ⁵¹V NMR, visible UV and IR spectroscopy, and the differentiating dissolution methods. In an aqueous solution and at optimal pH (3.7), the monometallic complexes [Pd₃(PW₉O₃₄)₂]^12–and [Pd₃(PW₉O₃₄)₂Pd _n O _x H _y ] ^q–(n _av= 3), the bimetallic complexes [Pd₂Cu(PW₉O₃₄)₂]^12–, [Pd₂Fe(PW₉O₃₄)₂]^11–, and [PdFe₂(PW₉O₃₄)₂]^10–, and a mixture of the [Pd₃(PW₉O₃₄)₂Pd _n O _x H _y ] ^q–(n _av 10) + [(VO)₃(PW₉O₃₄)₂]^9–complexes are formed. The title complexes were isolated from solution as Cs⁺solid salts belonging to the same [M₃(PW₉O₃₄)₂] structural type.     

Photochemical substitution of benzene in the iron cyclohexadienyl complex [(η<Superscript>5</Superscript>-C<Subscript>6</Subscript>H<Subscript>7</Subscript>)Fe(η-C<Subscript>6</Subscript>H<Subscript>6</Subscript>)]<Superscript>+</Superscript>

The visible light irradiation of the [(η⁵-C₆H₇)Fe(η-C₆H₆)]⁺ cation (1) in acetonitrile resulted in the substitution of the benzene ligand to form the labile acetonitrile species [(η⁵-C₆H₇)Fe(MeCN)₃]⁺ (2). The reaction of 1 with Bu^tNC in MeCN produced the stable isonitrile complex [(η⁵-C₆H₇)Fe(Bu^tNC)₃]⁺ (3). The photochemical reaction of cation 1 with pentaphosphaferrocene Cp*Fe(η-cyclo-P₅) afforded the triple-decker cation with the bridging pentaphospholyl ligand, [(η⁵-C₆H₇)Fe(μ-η:η-cyclo-P₅)FeCp*]⁺ (4). The latter complex was also synthesized by the reaction of cation 2 with Cp*Fe(η-cyclo-P₅). The structure of the complex [3]PF₆ was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 2007.