The F1F0-ATPase binding site of dibutyltin-3-hydroxyflavone: Interactions with venturicidin,oligomycin and DCCD

Dibutyltin-3-hydroxyflavone bromide, Bu₂Sn(of), is a fluorescent probe inhibitor of mitochondrial F₁F₀ATPase which reacts with and titrates a component of F₀ with marked fluorescence enhancement and reacts similarly with chloroplast CF₁CF₀ and V-ATPases. Its use to monitor the interactions of other F₀ inhibitors (venturicidin, oligomycin, DCCD) with F₁F₀ATPase, both membrane-bound and purified by solubilization is described. Trialkyltins (Bu₃SnCl) back-titrate all Bu₂Sn(of) interaction sites; whereas the macrolide inhibitor venturicidin backtitrates 60±5% and oligomycin only 30±3% of Bu₂Sn(of) interaction sites. Bafilomycin, the macrolide inhibitor of V-ATPases, is inactive in this assay. DCCD acts in a different fashion from the other inhibitors. Current and potential applications of this fluorescent probe in mitochondrial bioenergetics and biogenesis are discussed.     

Dibutyltin-3-hydroxyflavone titrates a dissociable component (cofactor) of mitochondrial ATP synthase: An energy-transfer component linked to the ubiquinone pool

Dibutyltin-3-hydroxyflavone, Bu₂Sn(of), is a new fluorescence probe inhibitor of F₁F₀-ATPase and oxidative phosphorylation which inhibits by titration of an unidentified component of F₀. Its site of action is closely related to that of the trialkyltins and of venturicidin. This F₀ component is part of a pool of this component which is present in the heart mitochondrial inner membrane at levels of 5–7 nmol (mg protein)^?1 [18 ± 3 Bu₂Sn(of) sites per mol F₁F₀-ATPase]. However, ATPase activity in submitochondrial particles is near maximally inhibited by titration of approx. three Bu₂Sn(of) sites per mol F₁F₀-ATPase. Over 60% (60–80%) of the Bu₂Sn(of) interaction sites can be lost during the purification of F₁F₀-ATPase from submitochondrial particles. The number of Bu₂Sn(of) interaction sites in various F₁F₀-ATPase preparations is variable. The high numbers of Bu₂Sn(of) sites per mol F₁F₀-ATPase for heart mitochondria (18–21) and submitochondrial particles (15–19.5) decline in ATP synthase (11–15) to the low values obtained in Complex V (7–10.5) and the minimal values observed in highly purified F₁F₀?ATPase (3.5–5.6), thus indicating a variable dissociable component or cofactor of ATP synthase. The Bu₂Sn(of) interaction site, a component of ATP synthase, is responsive to the redox status of the respiratory chain and the interaction with Bu₂Sn(of) is with the reduced form of this component. Fluorescence titration studies show that this component is in redox equilibrium with the ubiquinone pool of the respiratory chain. It is proposed that this redox component serves as an inhibitor titratable cofactor pool which cycles through an F₀ interaction site (or sites) via a system which serves as an energy-transfer link between the respiratory chain and ATP synthase.     

Modulation of the F1FO‐ATPase function by butyltin compounds

Among butyltin compounds, tributyltin (TBT), widely exploited in the past in antifouling paints for its biocidal properties, is long known as one of the most harmful sea contaminants. Among the ascertained and universal toxicity mechanisms, TBT targeting F₁F_O‐ATPase and thus impairing cell bioenergetics, is here reviewed. While TBT effects on F₁F_O‐ATPase have been investigated for decades, the possible impact of the derivatives dibutyltin (DBT) and monobutyltin (MBT), produced by abiotic and/or biotic dealkylation of TBT and usually considered far less toxic, have been poorly explored up until now. Butyltin effects on F₁F_O‐ATPase and their underlying action mechanism seem to be tightly structure dependent. Butyltins are membrane‐active toxicants. Owing to its more pronounced lipophilicity TBT targets the transmembrane F_O sector, blocks ionic translocation and causes a dose‐dependent loss of sensitivity to F_O inhibitors such as oligomycin and N,N′‐dicyclohexylcarbodiimide. DBT strongly inhibits F₁F_O‐ATPase activity by competing with the Mg⁺² cofactor in the F₁ catalytic site but is ineffective on the enzyme sensitivity to F_O inhibitors. MBT is apparently ineffective. The possible contribution of DBT to the overall butyltin toxicity on membrane systems may not be neglectable since usually TBT coexists with its derivatives in organotin‐exposed animal tissues. Copyright © 2013 John Wiley & Sons, Ltd.     

Tri‐n‐butyltin binding to a low‐affinity site decreases the F1FO‐ATPase sensitivity to oligomycin in mussel mitochondria

In mussel digestive gland mitochondria the environmental pollutant tri‐n‐butyltin (TBT), other than strongly inhibiting ATPase activity at <1.0 μ m , at ≥1.0 μ m concentration was previously found to desensitize F₁F_O‐ATPase to the antibiotic oligomycin. While F₁F_O‐ATPase inhibition is widely known as one of the main mitochondrial damages caused by TBT, the enzyme's desensitization to oligomycin was quite unexpected. The possible mechanisms involved are here stepwise approached, aiming at enlightening the molecular mechanism(s) of TBT toxicity and the still poorly investigated oligomycin interaction with F_O. The findings strongly suggest that the oligomycin desensitization directly stems from the covalent binding of TBT to monothiols of the F₁F_O‐ATPase. This binding implies sulfur oxidation, irrespective of the possible formation of radical species in mitochondria, a mechanism which does not seem to be involved here. It is hypothesized that TBT interacts with the enzyme complex in at least two sites distinguished by different affinities: TBT binding to the high‐affinity site would lead to ATPase inhibition, while TBT binding to monothiols in the low‐affinity site could mirror the decrease in F₁F_O‐ATPase oligomycin sensitivity at ≥1.0 μ m TBT. Experiments carried out on inside‐out submitochondrial particles hint that TBT binding destabilizes the oligomycin‐blocked F_O conformation, allowing proton flux recovery within F_O, without uncoupling the catalytic function from proton channeling. Copyright © 2012 John Wiley & Sons, Ltd.     

Struktur‐ und magnetochemische Untersuchungen an Ba5Mn3F19 und verwandten Verbindungen AII5MIII3F19

Structural and Magnetochemical Studies of Ba₅Mn₃F₁₉ and Related Compounds A^II₅M^III₃F₁₉ Single crystal structure determinations by X‐ray methods were performed at the following compounds, crystallizing tetragonally body‐centred (Z = 4): Sr₅V₃F₁₉ (a = 1423.4(2), c = 728.9(1) pm), Sr₅Cr₃F₁₉ (a = 1423.5(2), c = 728.1(1) pm), Ba₅Mn₃F₁₉ (a = 1468.9(1), c = 770.3(1) pm, Ba₅Fe₃F₁₉ (a = 1483.5(1), c = 766.7(1) pm), and Ba₅Ga₃F₁₉ (a = 1466.0(2), c = 760.1(2) pm). Only Ba₅Mn₃F₁₉ was refined in space group I4cm (mean distances for elongated octahedra Mn1–F: 185/207 pm equatorial/axial; for compressed octahedra Mn2–F: 199/182 pm), the remaining compounds in space group I4/m. In all cases the octahedral ligand spheres of the M1 atoms showed disorder, the [M1F₆] octahedra being connected into chains in one part of the compounds and into dimers in the other. The magnetic properties of the V, Cr and Mn compounds named above and of Pb₅Mn₃F₁₉ and Sr₅Fe₃F₁₉ as well were studied; the results are discussed in context with the in part problematic structures.     

Potential energy surfaces and nonadiabatic transitions in the asymptotic regions of ICN photodissociation to study the interference effects in the F1 and F2 spin-rotation levels of the CN products

One of the most spectacular yet unsolved problems for the ICN -band photodissociation is the non-statistical spin-rotation F₁ = N + 1/2 and F₂ = N − 1/2 populations for each rotation level N of the CN fragment. The F₁/F₂ population difference function f(N) exhibits strong N and λ dependences with an oscillatory behavior. Such details were found to critically depend on the number of open-channel product states, namely, whether both I (²P_3/2) and I (²P_1/2) are energetically available or not as the dissociation partner. First, in the asymptotic region, the exchange and dipole-quadrupole inter-fragment interactions were studied in detail. Then, as the diabatic basis, we took the appropriate symmetry adapted products of the electronic and rotational wavefunctions for the F₁ and F₂ levels at the dissociation limits. We found that the adiabatic Hamiltonian exhibits Rosen–Zener–Demkov type nonadiabatic transitions reflecting the switch between the exchange interaction and the small but finite spin-rotation interaction within CN at the asymptotic region. This non-crossing type nonadiabatic transition occurs with the probability 1/2, that is, at the diabatic limit through a sudden switch of the quantization axis for CN spin S from the dissociation axis to the CN rotation axis N . We have derived semiclassical formulae for f(N) and the orientation parameters with a two-state model including the 3A′ and 4A′ electronic states, and with a four-state model including the 3A′ through 6A′ electronic states. These two kinds of interfering models explain general features of the F₁ and F₂ level populations observed by Zare's group and Hall's group, respectively. © 2018 Wiley Periodicals, Inc.     

Sn(I) halides: Novel binary compounds of tin and their application in synthetic chemistry

Metalloid cluster compounds are ideal model compounds for the area between the molecular and solid state, i.e. the nanometer regime. For the synthesis of metalloid cluster compounds, the disproportionation reaction of a metastable subhalide is a fruitful synthetic route. In the case of tin, monohalides are needed for this synthetic route as tin(II) halides are too stable to be used. Due to thermodynamic data, gaseous SnBr should be formed at 1370 °C, and by applying a co-condensation technique it can be trapped at −196 °C and prepared in synthetic scale. Herein first analyses of SnBr are presented, showing that SnBr is more reactive than the corresponding GeBr, already disproportionating quantitatively to elemental tin and SnBr₂ on heating to room temperature. By applying nitrogen-based donor molecules like NnBu₃ or pyridine, the reactivity can be moderated and the solubility is enhanced leading e.g. to an SnBr emulsion, which can be used for the synthesis of metalloid cluster compounds of tin.     

Darstellung und Eigenschaften von Tetra(n-butyl)ammonium-cis-trifluorophthalocyaninato(2–)zirconat(IV) und -hafnat(IV); Kristallstruktur von (nBu4N)cis[Hf(F)3pc2–]

Preparation and Properties of Tetra(n-butyl)ammonium cis -Trifluorophthalocyaninato(2–)zirconate(IV) and -hafnate(IV); Crystal Structure of (ⁿBu₄N) ^cis [Hf(F)₃pc^2–] cis-Dichlorophthalocyaninato(2–)metal(IV) of zirconium and hafnium reacts with excess tetra(n-butyl)-ammoniumfluoride trihydrate to yield tetra(n-butyl)-ammonium cis-trifluorophthalocyaninato(2–)metalate(IV), (ⁿBu₄N)^cis[M(F)₃pc^2–] (M = Zr, Hf). (ⁿBu₄N)^cis[Hf(F)₃pc^2–] crystallizes in the monoclinic space group P2₁/n (# 14) with cell parameters a = 13.517(1) Å, b = 13.856(1) Å, c = 23.384(2) Å, α = 92.67(1)°, Z = 4. The Hf atom is in a ”︁square base-trigonal cap”︁”︁ polyhedron, coordinating three fluorine atoms and four isoindole nitrogen atoms (N_iso). The Hf atom is sandwiched between the (N_iso)₄ and F₃ planes (d(Hf–Ct_N) = 1.218(3) Å; d(Hf–Ct_F) = 1.229(3) Å; Ct_N/F: centre of the (N_iso)₄, respectively F₃ plane). The average Hf–N_iso and Hf–F distances are 2.298 and 1.964 Å, respectively, the average F–Hf–F angle is 84.9°. The pc^2– ligand is concavely distorted. The optical spectra show the typical metal independent π-π* transitions of the pc^2– ligand at c. 14700 and 29000 cm^–1. In the FIR/MIR spectra vibrations of the MF₃ skeleton are detected at 545, 489, 274 cm^–1 (M = Zr) and 536, 484, 263 cm^–1 (M = Hf), respectively.     

1,3 Dichloro- and 1,3 dibromotetra-n-butyldistannoxane mixtures: ligand redistribution and fluxional dynamics in distannoxanes

The halogen redistribution reaction in the binary [ⁿBu₂SnCl]₂O/[ⁿBu₂SnBr]₂O system is examined by ¹¹⁹Sn- and ¹³C-NMR spectroscopy. Binary mixtures of [ⁿBu₂SnCl]₂O and [ⁿBu₂SnBr]₂O reach equilibrium rapidly at room temperature. The reactant dimers are found to be in equilibrium with all five possible mixed distannoxane dimers in the equimolar mixture. These mixed distannoxane dimers differ in the ratio of Cl and Br as well as the relative positioning of the halogens. The mechanism responsible for the rapid formation of the mixed Cl:Br distannoxane dimers is found to proceed via bimolecular collisions producing a four-centered transition state, which in turn undergoes a concerted exchange of the halogens. The equilibrium concentrations of the reactant and product dimers are well represented by a statistical distribution, indicating that Cl and Br exhibit equivalent donor abilities. At 298 K, the NMR spectral data are consistent with time-averaged structures arising from rapidly interconverting rigid ladder pairs. Lowering the temperature to 173 K failed to freeze out this fluxional process. A reversible configurational rearrangement is also observed in which rotation about the oxygen---exocyclic tin bond results in the mutual exchange of halogens associated with the same exocyclic tin atom.     

Synthesis and reactivity of alkynyl-linked phosphonium borates

The phosphine tBu₂PC?CH ( 1 ) was reacted with B(C₆F₅) to give the zwitterionic species tBu₂P(H)C?CB(C₆F₅)₃ ( 2 ). The analogous species tBu₂P(Me)C?CB(C₆F₅)₃ ( 3 ), tBu₂P(H)C?CB(Cl)(C₆F₅)₂ ( 4 ), tBu₂P(H)C?CB(H)(C₆F₅)₂ ( 5 ), and tBu₂P(Me)C?CB(H)(C₆F₅) ₂ ( 6 ) were also prepared. The salt [tBu₂P(H)C?CB(C₆F₅)₂(THF)][B(C₆F₅)₄] ( 7 ) was prepared through abstraction of hydride by [Ph₃C][B(C₆F₅)₄]. Species 5 reacted with the imine tBuN?CHPh to give the borane–amine adduct tBu₂PC?CB[tBuN(H)CH₂Ph](C₆F₅)₂ ( 8 ). The related phosphine Mes₂PC?CH ( 9 ; Mes=C₆H₂Me₃) was used to prepare [tBu₃PH][Mes₂PC?CB(C₆F₅)₃] ( 10 ) and generate Mes₂PC?CB(C₆F₅)₂. The adduct Mes₂PC?CB(NCMe)(C₆F₅)₂ ( 11 ) was isolated. Reaction of Mes₂PC?CB(C₆F₅)₂ with H₂ gave the zwitterionic product (C₆F₅)₂(H)BC(H)?C[P(H)Mes₂][(C₆F₅)₂BC?CP(H)Mes₂] ( 12 ). Reaction of tBu₂PC?CB(C₆F₅)₂, a phosphine–borane generated in situ from 5 , with 1‐hexene gave the species [tBu₂PC?CB(C₆F₅)₂](CH₂CHnBu)[tBu₂PC?CB(C₆F₅)₂] ( 13 ) and subsequent reaction with methanol or hexene resulted in the formation of [tBu₂P(H)C?CB(C₆F₅)₂](CH₂CHnBu)[tBu₂PC?CB(C₆F₅)₂](OMe) ( 14 ) or the macrocycle {[tBu₂PC?CB(C₆F₅)₂](CH₂CH₂nBu)}₂ ( 15 ), respectively. In a related fashion, the reaction of 13 with THF afforded the macrocycle [tBu₂PC?CB(C₆F₅)₂](CH₂CHnBu)[tBu₂PC?CB(C₆F₅)₂][O(CH₂)₄] ( 16 ), although treatment of tBu₂PC?CB(C₆F₅)₂ with THF lead to the formation of {[tBu₂PC?CB(C₆F₅)₂][O(CH₂)₄]}₂ ( 17 ). In a related example, the reaction of Mes₂PC?CB(C₆F₅)₂ with PhC?CH gave {[Mes₂PC?CB(C₆F₅)₂](CH?CPh)}₂ ( 18 ). Compound 5 reacted with AlX₃ (X=Cl, Br) to give addition to the alkynyl unit, affording (C₆F₅)₂BC(H)?C[P(H)tBu₂](AlX₃) (X=Cl 19 , Br 20 ). In a similar fashion, 5 reacted with [Zn(C₆F₅)₂] ? C₇H₈, [Al(C₆F₅)₃] ? C₇H₈, or HB(C₆F₅)₂ to give (C₆F₅)₃BC(H)?C[P(H)tBu₂][Zn(C₆F₅)] ( 21 ), (C₆F₅)₃BC(H)?C[P(H)tBu₂][Al(C₆F₅)₂] ( 22 ), or [(C₆F₅)₂B]₂HC?CH[P(H)tBu₂] ( 23 ), respectively. The implications of this reactivity are discussed.     

Organonickel(II) Complexes with Anionic N-Donor Ligands. Hydration of coordinated nitriles at a nickel(II) site

The hydroxo complex (Bu₄N)₂[Ni₂(C₆F₅)₄(μ-OH)₂]reacts with 2,3,4,5,6-pentafluoro benzenamine (C₆F₅-NH₂), 1,3-diaryltriaz-1-enes (ArNH? N=N? Ar, Ar = Ph, 4-MeC₆H₄, 4-MeOC₆H₄), 7-aza-1H-indole (= 1H-pyrrolo[2.3-b]pyridine; Hazind), N-phenylpyridin-2-amine(pyNHPh), and N-phenylpyridine-2-carboxamide (py-CONHPh) at room temperature in acetone to give the binuclear complexes (Bu₄N)₂[Ni₂(C₆F₅)₄(μ-C₆F₅NH)₂] ( 1 ) and (Bu₄N)₂[{Ni(C₆F₅)₂} 2(μ-OH)(μ-azind)] ( 2 ) and the mononuclear complexes Bu₄N[Ni(C₆F₅)2(ArN₃Ar)] ( 3 – 5 ), Bu₄N[Ni(C₆F₅)₂(pyNPh)] ( 6 ), and Bu₄N[Ni(C₆F₅)₂(pyCONPh)] ( 7 ). The hydroxo.complex (Bu₄N)₂[{Ni(C₆F₅)2-(μ-OH)}₂] promotes the nucleophilic addition of water to pyridine-2-carbonitrile, 2-aminoacetonitrile, and 2-(dimethylamino)acetonitrile, and complexes 8 – 10 containing pyridine-2-carboxamidato, 2-aminoacetamidato and 2-(dimethylamino)acetamidato ligands are formed. Analytical (C, H, N) and spectroscopic (IR, ¹H and ¹⁹F-NMR, and FAB-MS) data were used for structural assignments. A single-crystal X-ray diffraction study of (Bu₄N)₂[{Ni(C₆F₅)₂}₂(μ-OH)(μ-azind)] ( 2 ) established the binuclear nature of the anion; the two Ni-atoms are bridged by an OH group and a 7-aza-7H-indol-7-yl group, but the central Ni? O? Ni? N? C? N ring is not planar, the dihedral angle between the Ni? O? Ni and Ni? N? C? N? Ni planes being 84.4°.     

(Bu4N)[Re{NB(C6F5)3}Cl4(OH2)] – Struktur und EPR-Spektren

(Bu₄N)[Re{NB(C₆F₅)₃}Cl₄(OH₂)] – Structure and EPR Spectra The title compound represents the first structurally characterized rhenium(VI) complex with a bridging nitrido ligand. It has been prepared by the reaction of (Bu₄N)[ReNCl₄] with B(C₆F₅)₃ in CH₂Cl₂. An almost linear (170.5(3)°) nitrido bridge with a Re≡N bond length of 1.672(4) Å is formed. The coordination position trans to the multiple bond is occupied by a molecule of water. The EPR parameters of the title complex are reported and discussed with those of [ReNCl₄]^– concerning the spin-density distribution in the ‘‘ReNCl₄”︁”︁ unit.     

Bifunctional fluorescent thiacalix[4]arene based chemosensor for Cu and F ions

A new thiacalix[4]arene based fluorescent sensor bearing two dansyl groups has been synthesized in cone conformation. In CH₃CN:CH₂Cl₂ (1:1), the presence of Cu (II) induces the formation of a 1:1 metal:ligand complex, which exhibits increasing emission at 433 nm at the expense of the fluorescent emission of 1 centered at 504 nm. The detection limit of the sensor for Cu²⁺ is 2×10⁻⁷ mol L⁻¹. For anion sensing, 1 shows a high selectivity for fluoride ions over other anions tested.     

A reversible fluorescence “ON–OFF–ON” sensor for sequential detection of F− and Cu2+ ions and its application as a molecular-scale logic device and security keypad lock

A new azoimine receptor, R₁, was synthesized by Schiff base condensation of 4-(4-butylphenyl) azophenol and 2,6-diaminopyridine and acts as a colorimetric and fluorometric chemosensor for F^? and also toward Cu²⁺ ions in aqueous environment. UV–Vis absorption and fluorescent emission spectra were employed to study the sensing process. Emission study was performed to examine the dual sensing ability of the obtained probe with sequential addition of F^? followed by Cu²⁺ and vice versa. The receptor is an efficient “ON–OFF” fluorescent probe for the fluoride ion. Also, R₁ + F^? operated as an “OFF–ON” fluorescent sensor for Cu²⁺ ions. Considering emission intensity and absorption wavelength for F^? and Cu²⁺ ions, a molecular system was developed with the ability to mimic the functions of XNOR logic gating on the molecular level. In addition, R₁ behaved as a molecular security keypad lock with F^? and Cu²⁺ inputs. The keypad lock operation is particularly important, as the output of the system depends not only on the proper combination but also on the order of input signals, creating the correct password that can be used to “open” this molecular keypad lock through strong fluorescence emission at 460?nm.     

Polymerization of 1‐hexene with bis[N‐(3‐tert‐butylsalicylidene)phenylaminato]titanium(IV) dichloride using iBu3Al/Ph3CB(C6F5)4 as a cocatalyst

1‐Hexene polymerization was investigated with bis[N‐(3‐tert‐butylsalicylidene)phenylaminato]titanium(IV) dichloride ( 1 ) using ⁱBu₃Al/Ph₃CB(C₆F₅)₄ as a cocatalyst. This catalyst system produced poly(1‐hexene) having a high molecular weight (M_w = 445 000–884 000, 0–60°C). ¹³C NMR spectroscopy revealed that the high molecular weight poly(1‐hexene) possesses an atactic structure with about 50 mol‐% of regioirregular units.     

Difluorophosphoryl Nitrene F2P(O)N: Matrix Isolation and Unexpected Rearrangement to F2PNO

Triplet difluorophosphoryl nitrene F₂P(O)N (X³A′′) was generated on ArF excimer laser irradiation (λ=193 nm) of F₂P(O)N₃ in solid argon matrix at 16 K, and characterized by its matrix IR, UV/Vis, and EPR spectra, in combination with DFT and CBS‐QB3 calculations. On visible light irradiation (λ>420 nm) at 16 K F₂P(O)N reacts with molecular nitrogen and some of the azide is regenerated. UV irradiation (λ=255 nm) of F₂P(O)N (X³A′′) induced a Curtius‐type rearrangement, but instead of a 1,3‐fluorine shift, nitrogen migration to give F₂PON is proposed to be the first step of the photoisomerization of F₂P(O)N into F₂PNO (difluoronitrosophosphine). Formation of novel F₂PNO was confirmed with ¹⁵N‐ and ¹⁸O‐enriched isotopomers by IR spectroscopy and DFT calculations. Theoretical calculations predict a rather long P? N bond of 1.922 Å [B3LYP/6‐311+G(3df)] and low bond‐dissociation energy of 76.3 kJ mol^?1 (CBS‐QB3) for F₂PNO.     

Spectrofluorometric study of 1,4-diaminoanthraquinone-calcium complex in aqueous sulfuric acid mediums: Spectrofluorometric determination of calcium

The spectrofluorometric study was made of the complex 1,4-diaminoanthraquinone-Ca in aqueous sulfuric mediums [λ_max,ex = 410 nm; λ_max,em = 580 nm; 50% H₂O; stable for at least 4 hr; range temperature OPTIMUM = 20–35 °C; [R]_optimum = 2 × 10⁻⁴M; stoichiometry 2:1 (fluorescent complex) and 1:1 (no fluorescent complex)]. A new method for the spectrofluorometric determination of Ca traces is proposed for concentrations between 150 and 400 ppb. The relative error and the interferences of the method have been investigated.     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalyse von cis‐ und trans‐(n‐Bu4N)2[PtF2(ox)2] und (n‐Bu4N)2[PtF4(ox)]

Synthesis, Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of cis‐ and trans‐(n‐Bu₄N)₂[PtF₂(ox)₂] and (n‐Bu₄N)₂[PtF₄(ox)] By treatment of trans‐(n‐Bu₄N)₂[PtCl₂(ox)₂] and (n‐Bu₄N)₂[PtCl₄(ox)] with XeF₂ in propylene carbonate cis‐ and trans‐(n‐Bu₄N)₂[PtF₂(ox)₂] ( 1 , 2 ) and (n‐Bu₄N)₂[PtF₄(ox)] ( 3 ) are formed which have been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of trans(n‐Bu₄N)₂[PtF₂(ox)₂] ( 2 ) (tetragonal, space group P4₂/n, a = 15.5489(9), b = 15.5489(9), c = 17.835(1)Å, Z = 4) und Cs₂[PtF₄(ox)] ( 3 ) (monoclinic, space group C2/m, a = 14.5261(7), b = 6.2719(4), c = 9.6966(9)Å, β = 90.216(8)°, Z = 4) reveal complex anions with nearly D_2h and C_2v point symmetry. The average bond lengths in the symmetrical coordinated axes are Pt—F = 1.93 ( 2 , 3 ) and Pt—O = 1.987 ( 2 ) and in the F^•—Pt—O′‐axes Pt—F^• = 1.957 and Pt—O′ = 1.977Å ( 3 ). The oxalato ligands are nearly planar with a maximum displacement of the ring atoms of 0.05 ( 2 ) und 0.01Å ( 3 ) to the calculated best planes. In the vibrational spectra the symmetric and antisymmetric PtF stretching vibrations are observed at 583 and 586 ( 2 ) and 576 and 568 cm^—1 ( 3 ). The PtF^• modes appear at 565 and 562 ( 1 ) and 560 cm^—1 ( 3 ). The PtO and PtO′ stretching vibrations are coupled with internal modes of the oxalato ligands and appear in the range of 400—800 cm^—1. Based on the molecular parameters of the X‐ray determinations ( 2 , 3 ) and estimated data ( 1 ) the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants are f_d(PtF) = 3.55 ( 2 ) and 3.38 ( 3 ), f_d(PtF^•) = 3.23 ( 1 ) and 3.20 ( 3 ), f_d(PtO) = 2.65 ( 1 ) and 2.84 ( 2 ) and f_d(PtO′) = 2.97 ( 1 ) and 3.00 mdyn/Å ( 3 ). Taking into account increments of the trans influence a good agreement between observed and calculated frequencies is achieved. The NMR shifts are δ(¹⁹⁵Pt) = 8485 ( 1 ), 8597 ( 2 ) and 10048 ppm ( 3 ), δ(¹⁹F) = —350 ( 2 ) and —352 ( 3 ) and δ(¹⁹F^•) = —323 ( 1 ) and —326 ppm ( 3 ) with the coupling constants ¹J(PtF) = 1784 ( 2 ) and 1864 ( 3 ) and ¹J(PtF^•) = 1525 ( 1 ) and 1638 Hz ( 3 ).     

Isolation of a Cationic Platinum(II) σ‐Silane Complex

The platinum complex [Pt(I^tBuⁱPr′)(I^tBuⁱPr)][BAr^F] interacts with tertiary silanes to form stable (<0 °C) mononuclear Pt^II σ‐SiH complexes [Pt(I^tBuⁱPr′)(I^tBuⁱPr)(η¹‐HSiR₃)][BAr^F]. These compounds have been fully characterized, including X‐ray diffraction methods, as the first examples for platinum. DFT calculations (including electronic topological analysis) support the interpretation of the coordination as an unusual η¹‐SiH. However, the energies required for achieving a η²‐SiH mode are rather low, and is consistent with the propensity of these derivatives to undergo Si?H cleavage leading to the more stable silyl species [Pt(SiR₃)(I^tBuⁱPr)₂][BAr^F] at room temperature.     

The morphological,optical and electrical properties of SnO2:F thin films prepared by spray pyrolysis

Combining the spray pyrolysis and the sol–gel techniques gives the possibility to produce Fluorine doped Tin oxide (SnO₂:F) thin films. Transparent conducting SnO₂:F thin films have been deposited on glass substrates by the spray pyrolysis technique. This technique for the fabrication of SnO₂:F filmsby combining sol–gel process and the spray pyrolysis technique ispresented in this paper. The Sol–gel precursors have been successfully prepared using SnCl₂·5H₂O and (Ac)F₃. The structural, electrical, and optical properties of these films were investigated. The high resolution transmission electron microscopy (HRTEM) and selected area diffraction (SAD) patterns of SnO₂:F films show that the gel films lead to a tetragonal structure. The X‐ray diffraction pattern of the films deposited at substrate temperature 530° , the orientation of the films was predominantly [110]. In addition, the surface chemical components were also examined by X‐ray photoelectron spectroscopy (XPS) showing the SnO₂:F deposited with the atomic concentration ratios Sn/F 1.82:1. The minimum sheet resistance was 50 Ω and average transmission in the visible wavelength range of 300 to 800 nm was 87.25%. Copyright © 2008 John Wiley & Sons, Ltd.