A computational study of SbnF5n (n = 1-4): Implications for the fluoride ion affinity of nSbF5

This contributions shows with a series of ab initio MP2 and DFT (BP86 and B3-LYP) computations with large basis sets up to cc-pVQZ quality that the literature value of the standard enthalpy of depolymerization of Sb₄F_20(g) to give SbF_5(g) (+18.5 kJ mol⁻¹) [J. Fawcett, J.H. Holloway, R.D. Peacock, D.R. Russell, J. Fluorine Chem. 20 (1982) 9] is by about 50 kJ mol⁻¹ in error and that the correct value of (Sb₄F_20(g)) is +68 ± 10 kJ mol⁻¹. We assign , , and values for Sb_nF_5n with n = 2-4 and compare the results to available experimental gas phase data. Especially the MP2/TZVPP values obtained in an indirect procedure that rely on isodesmic reactions or the highly accurate compound methods G2 and CBS-Q are in excellent agreement with the experimental data, and reproduce also the fine experimental details at temperatures of 423 and 498 K. With these data and the additional calculation of [Sb_nF_5n+1]⁻ (n = 1-4), we then assessed the fluoride ion affinities (FIAs) of Sb_nF_5n(g), nSbF_5(g), nSbF_5(l) and the standard enthalpies of formation of Sb_nF_5n(g) and [Sb_nF_5n+1]⁻_(g): FIA(Sb_nF_5n(g)) = 514 (n = 1), 559 (n = 2), 572 (n = 3) and 580 (n = 4) kJ mol⁻¹; FIA(nSbF_5(g)) = 667 (n = 2), 767 (n = 3) and 855 (n = 4) kJ mol⁻¹; FIA(nSbF_5(l)) = 434 (n = 1), 506 (n = 2), 528 (n = 3) and 534 (n = 4) kJ mol⁻¹. Error bars are approximately ±10 kJ mol⁻¹. Also the related Gibbs energies were derived. Δ_fH°([Sb_nF_5n+1]⁻_(g)) = −2064 ± 18 (n = 1), −3516 ± 25 (n = 2), −4919 ± 31 (n = 3) and −6305 ± 36 (n = 4) kJ mol⁻¹.     

New synthesis and thermal studies of palladacycloalkanes and their precursors

A series of new palladacycloalkanes of formula cis-[PdL₂(CH₂)_n] (9. n = 6, L = PPh₃; 10. n = 6, L₂ = dppe; 11. n = 8, L = PPh₃; 12. n = 8, L₂ = dppe) have been prepared by two routes. In the first route, the precursor bis(1-alkenyl) complexes cis-[PdL₂((CH₂)_nCHCH₂)₂] (1. n = 2, L = PPh₃, 2. n = 2, L₂ = dppe, 3. n = 3, L = PPh₃, 4. n = 3, L₂ = dppe) were allowed to react with Grubb’s 2nd generation catalyst to give the palladacycloalkenes, cis-[PdL₂(CH₂)_nCHCH(CH₂)_n] (5. n = 2, L = PPh₃, 6. n = 2, L₂ = dppe, 7. n = 3, L = PPh₃, 8. n = 3, L₂ = dppe), which were then hydrogenated to the palladacycloalkanes, 9-12. In the second route, the di-Grignard reagents BrMg(CH₂)_nMgBr (n = 6, 8) were reacted with the palladium complex [PdCl₂(COD)] followed by immediate ligand displacement to form the respective palladacycloalkanes 10 and 12. The complexes obtained were characterized by a range of spectroscopic and analytical techniques. Thermal decomposition studies were carried out on the palladacycloalkanes 9-12 and the main organic products shown to be 1-alkenes and 2-alkenes.     

Thermochemistry of intercalation of n-alkylmonoamines into lamellar hydrated barium phenylarsonate

Hydrated layered crystalline barium phenylarsonate, Ba(HO₃AsC₆H₅)₂·2H₂O was used as host for intercalation of n-alkylmonoamine molecules CH₃(CH₂)_n-NH₂ (n = 1-4) in aqueous solution. The amount intercalated (n_f) was followed batchwise at 298 ± 1 K and the variation of the original interlayer distance (d) for hydrated barium phenylarsonate (1245 ppm) was followed by X-ray powder diffraction. Linear correlations were obtained for both d and n_f as a function of the number of carbon atoms in the aliphatic chain (n_c): d = (2225 ± 32) + (111 ± 11)n_c and n_f = (2.28 ± 0.15) − (11.50 ± 0.03)n_c. The exothermic enthalpies of intercalation increased with n_c, which was derived from the monomolecular amine layer arrangements with the longitudinal axis inclined by 60° to the inorganic sheets. The intercalation was followed by titration with amine at the solid/liquid interface and gave the enthalpy/number of carbons correlation: ΔH = −(7.25 ± 0.40) − (1.67 ± 0.10)n_c. The negative Gibbs free energies and positive entropic values reflect the favorable host/guest intercalation processes for this system.     

New N,N-amino-diphosphonate-containing methacrylic derivatives, their syntheses and radical copolymerizations with MMA

Hydroxy-amino-diphosphonates HO-C_n-NH₂, with 2 ? n ? 11, have been successfully synthesized via the Kabachnick-Field reaction at 70 °C with high yields. These hydroxy compounds are then reacted with methacryloyl chloride to lead to novel amino-diphosphonate methacrylates MAC_nNP₂ (with 2 ? n ? 11). These highly pure methacrylate monomers were obtained with yields higher than 75%. Radical copolymerizations of MAC_nNP₂ (with 2 ? n ? 11) with MMA have been conducted and the r₁ values (related to MAC_nNP₂) are in the range of 1.1-1.3, and r₂ values (related to MMA) about 0.8; this shows that the diphosphonate groups are statistically bonded to the methacrylic backbone.     

Study on the pressure induced charge transfer phase transition in (C5H11)4N(FeFe(C2O2S2)3) by means of μSR spectroscopy

We have investigated the magnetic properties of iron mixed-valence complexes, (n-C_nH_2n+1)₄N[Fe^IIFe^III(dto)₃] (dto = C₂O₂S₂, n = 3, 5), in which not only a ferromagnetic transition but also a novel charge transfer phase transition (CTPT) take place [1]. This CTPT can be observed under ambient pressure for n = 3, while it appears abruptly above 0.5 GPa for n = 5 [2]. Recently, we have measured the muon spin relaxation (μSR) for the CTPT of n = 3, which revealed the dynamical process of electron-transfer between Fe^II and Fe^III and its frequency was estimated at about 0.1 MHz [3]. To investigate the pressure induced CTPT for n = 5, we carried out the μSR measurement for n = 5 at 150 K between 0.30 and 0.64 GPa with the ⁴He gas-operated pressure system. The asymmetry of the muon spin relaxation for n = 5 with Cu-Be pressure cell was almost constant up to 0.55 GPa, while it rapidly decreased with increasing pressure above 0.60 GPa. This result shows that the applied pressure causes the spin fluctuation due to the CTPT, which induces the decrease of the asymmetry of muon spin relaxation. This experiment can correctly decide the phase transition pressure from the absence to the appearance of the CTPT for n = 5.     

Are closed clusters expected from the (n + 1) skeletal electron pairs rule in alanes and gallanes? A DFT structural study of AnHn + 2 (A = Al, Ga, and n = 4-6)

It has been suggested recently that the alanes Al_nH_n + 2 can be treated by the polyhedral skeletal electron pair theory (PSEPT) of Wade and Mingos (W-M) as it was successful for their borane congeners such as B_nH_n + 2, well known as the deprotonated B_nH_n²⁻. To do so, the neutral Al_nH_n + 2 have been considered as Al_nH_n²⁻ + 2H⁺. The additional hydrogens donate their electrons to the Al_nH_n polyhedral framework and according to the n + 1 electron pairs rule; these clusters should have closo-polyhedral structures. In this work the homologous gallanes, the structures and stabilities of Ga_nH_n + 2 are studied at high levels of calculational theory and we investigated the applicability of the W-M rule to the alanes and gallanes A_nH_n + 2 (n = 4-6; A = Al, Ga). It will be shown that the presence of bridging hydrogen atoms reduces the compactness of the corresponding polyhedron and so these species do not have the closed structures. The computations were performed at B3LYP/6-311+G(d,p), BPW91/6-311G(d,p) and B3LYP/6-311+G(3df,2p) levels of theory. Our interest in these compounds includes their potential use as hydrogen storage species and future clean sources of energy.     

Synthesis and characterization of some organotin(IV) adducts containing a related series of pyridines: Crystal structure of [SnMe2Cl2(bu2bpy)]

Organotin(IV) complexes of [SnR_(4−n)Cl_n] (n = 2, R = Me, ⁿBu; n = 1, R = Ph) react with the bidentate pyridyl ligand 4,4′-di-tert-butyl-2,2′-bipyridine (bu₂bpy) to give hexa-coordinated adducts with the general formula [SnR_(4−n)Cl_n(bu₂bpy)]. However, the reaction of these organotin(IV) complexes with the corresponding monodentate ligand 4-tert-butylpyridine (bupy) resulted in the formation of the hexa-coordinated complex [SnMe₂Cl₂(bupy)₂] and the penta-coordinated complexes [SnR_(4−n)Cl_n(bupy)] (n = 2, R = ⁿBu; n = 1, R = Ph). Moreover, the reaction of the above organotin(IV) complexes with 4,4′-trimethylenedipyridine (tmdp) yields hexa-coordinated adducts with the general formula [SnR₂Cl₂(tmdp)] (R = Me, ⁿBu) and the penta-coordinated complex [ClPh₃Sn-μ-(tmdp)SnPh₃Cl] in the solid state. The resulting complexes have been characterized by multinuclear NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy and elemental analysis. NMR data shows that the triphenyltin(IV) adducts are not stable in solution and dissociate to give tetra-coordinated tin(IV) complexes. The X-ray crystal structure determination of [SnMe₂Cl₂(bu₂bpy)] reveals that the tin atom is hexa-coordinated in an octahedral geometry with a trans-[SnMe₂] configuration.     

A new approach to the synthesis of oligomers. Application to the synthesis of p-phenylene thioether wires

Oligothioethers 4-RC₆H₄(SC₆H₄-4)_nX (n = 1-3; X = Br, I; R = NO₂; X = Br; R = MeO. n = 1 and 2; X = I; R = MeO. n = 4; X = Br; R = NO₂) have been prepared through a process involving (i) palladium-catalyzed C-S coupling between 4-RC₆H₄(SC₆H₄-4)_n−1I and 4-BrC₆H₄SH to give 4-RC₆H₄(SC₆H₄-4)_nBr and (ii) copper-catalyzed replacement of Br by I.     

Reverse atom transfer radical polymerisation (RATRP) of methacrylates using copper(I)/pyridinimine catalysts in conjunction with AIBN

N-n-Propyl-2-pyridylmethanimine, 1, N-n-octyl-2-pyridylmethanimine, 2, N-n-lauryl-2-pyridylmethanimine, 3, and N-n-octadecyl-2-pyridylmethanimine, 4 have been used in conjunction with copper(II) bromide and azo initiators for the reverse atom transfer radical polymerisation of a range of methacrylates. AIBN to Cu^IIBr₂ ratios of 0.5:1, 0.75:1 and 1:1 give PMMA with M_n 11 500 g mol⁻¹ (PDi = 1.24) (at 22% conversion), 12 500 g mol⁻¹ (PDi = 1.06) (at 83% conversion) and 10 900 g mol⁻¹ (PDi = 1.11) (at 84% conversion), respectively. A Cu^IIBr₂ complex is demonstrated to be needed at the start of the reaction for good control over molecular weight and polydispersity as reactions using Cu(I)Br as catalyst yielded PMMA of M_n 31 000 g mol⁻¹ (PDi = 2.90), reactions with no copper yield PMMA of M_n 33 000 g mol⁻¹ (PDi = 2.95). The RATRP of styrene was carried out using Cu^IIBr₂ as catalyst. AIBN to Cu^IIBr₂ ratio of 0.5:1, 0.75:1 and 1:1 gave PS with M_n = 12 400 g mol⁻¹ (PDi = 1.27) at low conversion, M_n = 15 500 g mol⁻¹ (PDi = 1.11) and 12 400 g mol⁻¹ (PDi = 1.38), respectively at ∼85% conversion. A series of block copolymers of MMA with BMA, BzMA and DMEAMA (15 600 g mol⁻¹ (PDi = 1.18), 13 300 g mol⁻¹ (PDi = 1.14) 15 300 g mol⁻¹ (PDi) = 1.16), using a PMMA macroinitiator were prepared. Emulsion polymerisation of MMA using [initiator]:[Cu^(II)Br₂] ratio = 0.5:1 with Brij surfactant gave a linear increase of M_n with respect to conversion, final M_n = 112 800 g mol⁻¹ (PDi = 1.42). Further reactions were carried out with [initiator]:[Cu^(II)Br₂] ratio = 0.75:1 and 1:1. Both giving PMMA with M_n ∼ 32 000 g mol⁻¹ (PDi ∼ 2.4). These reactions exhibit no control, this is because the azo initiator is present in excess and all of the monomer is consumed by a free radical polymerisation as opposed to a controlled reaction. Particle size analysis (DLS) showed the particle size between 160 and170 nm in all cases.     

Insertion of tin(II) bromide into Pt–X (X = Cl,Br) bond of dimethylplatinum(IV) complexes: A novel polymorphic form of [PtBr2(bpy)]

The platinum(II) complex [PtMe₂(bpy)] (bpy = 2,2′-bipyridine) reacted with a large excess of dihaloalkanes X(CH₂)_nX (n = 1, X = Cl; n = 4, X = Br) to form the platinum(IV) complexes [PtMe₂X{(CH₂)_nX}(bpy)] (n = 1, X = Cl, 1a; n = 4, X = Br, 1b). The reaction of complexes 1a and 1b with SnBr₂ resulted in insertion of SnBr₂ into Pt–X (X = Cl, Br) bond to afford the trihalostannyl complexes [PtMe₂(SnBr₂X){(CH₂)_nX}(bpy)] (n = 1, X = Cl, 2a; n = 4, X = Br, 2b). The synthesis of such trihalostannylplatinum(IV) complexes is reported for the first time. The complex 2a was decomposed in CH₂Cl₂ solution and single crystals of [PtBr₂(bpy)] (3a) were obtained. The X-ray structure determination of 3a revealed a new polymorphic form of [PtBr₂(bpy)]. The molecules undergo a remarkable stacking along the b-axis to form a zigzag Pt?Pt?Pt chain containing both short (3.799 Å) and long (5.175 Å) Pt?Pt separations through the crystal. The crystal structure is compared to that of the yellow modification of [PtBr₂(bpy)].     

Synthesis of novel lipophilic and/or fluorophilic ethers of perfluoro-tert-butyl alcohol, perfluoropinacol and hexafluoroacetone hydrate via a Mitsunobu reaction: Typical cases of ideal product separation

Fluorophilic ethers having the structure RC(CF₃)₂O(CH₂)₃C_nF_2n + 1 are obtained in high yields, when F-tert-butyl alcohol (R = CF₃), F-acetone hydrate (R = O(CH₂)₃C_nF_2n + 1), F-pinacol (R = C(CF₃)₂O(CH₂)₃C_nF_2n + 1) are reacted with 3-perfluoroalkyl-1-propanols (C_nF_2n + 1(CH₂)₃OH, n = 4, 6, 8, 10) in a Mitsunobu reaction (Ph₃P/DIAD [i-PrO₂CN = NCO₂Pr-i]/ether). The parent lipophilic ethers with the structure of (CF₃)₃CO(CH₂)₃C_nH_2n + 1 were prepared analogously using the corresponding fatty alcohols and F-tert-butyl alcohol. To achieve ideal separations, products were transferred to orthogonal phases relative to the other reaction components using fluorous extraction, fluorous solid-organic liquid filtration, or steam-distillation. Selected physical properties including melting and boiling point, together with fluorous partition coefficients of these ethers were determined and the figures obtained were qualitatively analyzed using relevant thermodynamic theories. Some of these ethers are liquids with rather low freezing points and are miscible with fluorocarbon solvents.     

Separation and quantification of [RhCln(H2O)6−n] (n = 0-6) complexes, including stereoisomers, by means of ion-pair HPLC-ICP-MS

A hyphenated ion-pair (tetrabutylammonium chloride—TBACl) reversed phase (C₁₈) HPLC-ICP-MS method (High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectroscopy) for anionic Rh(III) aqua chlorido-complexes present in an HCl matrix has been developed. Under optimum chromatographic conditions it was possible to separate and quantify cationic Rh(III) complexes (eluted as a single band), [RhCl₃(H₂O)₃], cis-[RhCl₄(H₂O)₂]⁻, trans-[RhCl₄(H₂O)₂]⁻ and [RhCl_n(H₂O)_6−n]³⁻ⁿ (n = 5, 6) species. The [RhCl_n(H₂O)_6−n]³⁻ⁿ (n = 5, 6) complex anions eluted as a single band due to the relatively fast aquation of [RhCl₆]³⁻ in a 0.1 mol L⁻¹ TBACl ionic strength mobile phase matrix. Moreover, the calculated t_1/2 of 1.3 min for [RhCl₆]³⁻ aquation at 0.1 mol kg⁻¹ HCl ionic strength is significantly lower than the reported t_1/2 of 6.3 min at 4.0 mol kg⁻¹ HClO₄ ionic strength. Ionic strength or the activity of water in this context is a key parameter that determines whether [RhCl_n(H₂O)_6−n]³⁻ⁿ (n = 5, 6) species can be chromatographically separated. In addition, aquation/anation rate constants were determined for [RhCl_n(H₂O)_6−n]³⁻ⁿ (n = 3-6) complexes at low ionic strength (0.1 mol kg⁻¹ HCl) by means of spectrophotometry and independently with the developed ion-pair HPLC-ICP-MS technique for species assignment validation. The Rh(III) samples that was equilibrated in differing HCl concentrations for 2.8 years at 298 K was analyzed with the ion-pair HPLC method. This analysis yielded a partial Rh(III) aqua chlorido-complex species distribution diagram as a function of HCl concentration. For the first time the distribution of the cis- and trans-[RhCl₄(H₂O)₂]⁻ stereoisomers have been obtained. Furthermore, it was found that relatively large amounts of ‘highly’ aquated [RhCl_n(H₂O)_6−n]³⁻ⁿ (n = 0-4) species persist in up to 2.8 mol L⁻¹ HCl and in 1.0 mol L⁻¹ HCl the abundance of the [RhCl₅(H₂O)]²⁻ species is only 8-10% of the total, far from the 70-80% as previously proposed. A 95% abundance of the [RhCl₆]³⁻ complex anion occurs only when the HCl concentration is above 6 mol L⁻¹. The detection limit for a Rh(III) species eluted from the column is below 0.147 mg L⁻¹.     

Thermotropic polyesters. 2: Synthesis, characterization and thermal transitions of copolyesters containing 4,4′-bis (ω-alkyloxy) biphenyl isophthalate units

Thermotropic copolyesters containing an isophthalate unit and mesogenic 4, 4′-bis (ω-hydroxyalkyloxy) biphenyls (n = 3, 4, 6) with different numbers of methylene units have been synthesized by melt polymerization. The number-average molar mass (M_n) was estimated from end group analysis by ¹H NMR. The copolymer compositions were also obtained from ¹H NMR. The thermal behavior of the copolymers containing even-even (n = 4, 6) and odd-even (n = 3, 4) pairings has been investigated and is also compared with that of the analogous homopolymers. The copolymers exhibit reduced melting point and extending liquid crystalline range identified using polarizing microscopy and DSC. All of the obtained compounds were characterized by conventional spectroscopic methods.     

Unsaturation in trinuclear cobalt carbonyl compounds of the type ECo3(CO)n (E = CH,CF, P,As; n = 9, 8, 7, 6) with Co3E tetrahedrane structures

Theoretical studies on the known trinuclear cobalt carbonyl derivatives ECo₃(CO)₉ (E = CH, CF, P, As) predict structures with carbonyl groups bridging each edge of the Co₃ triangle in contrast with experiment where structures with all terminal carbonyl groups are found in all cases. However, the energy differences are predicted to be rather small ranging from 4 ± 2 kcal/mol for FCCo₃(CO)₉ to 10 ± 3 kcal/mol for AsCo₃(CO)₉. The global minima for the unsaturated ECo₃(CO)_n (n = 8, 7, 6) derivatives generally have two (for n = 8) or three (for n = 7 and 6) carbonyl groups bridging the edges of the Co₃ triangle. However, structures with all terminal carbonyl groups are also found in all cases as well as higher energy structures in which one of the carbonyl groups bridges all three cobalt atoms. The fluoromethinyl derivatives FCCo₃(CO)_n (n = 9, 8, 7) are anomalous since their unbridged structures or structures with a carbonyl group bridging all three cobalt atoms are closer in energy to the doubly or triply bridged global minima than is the case for the other ECo₃(CO)_n derivatives.     

Liquid–liquid equilibrium data for binary perfluoroalkane (C6 and C8) + n-alkane systems

This study aims to make detailed measurements of the solubility data for perfluoroalkane + n-alkane systems. Using a laser-scattering technique developed in our laboratory, we determined the liquid–liquid equilibria (LLE) for three binary mixtures: perfluorohexane + n-hexane, perfluorohexane + n-octane, and perfluorooctane + n-octane. The experimental LLE data were represented by the NRTL equation. In addition, the activity coefficients obtained from the experimental LLE data were compared with those obtained from the vapor–liquid equilibrium (VLE) data.     

Tin(IV) and organotin(IV) derivatives of bis(pyrazolyl)acetate: Synthesis, spectroscopic characterization and behaviour in solution.: X-ray single crystal study of bis(pyrazol-1-yl)acetatotri-iodotin(IV) [SnI3(bdmpza)]

Novel heteroscorpionate-containing tin and organotin(IV) complexes, [SnR_nX_3 − n(L)], R = Me, Buⁿ, Ph, or cy; X = Cl, Br or I, n = 0, 1, 2 or 3; L = bis(pyrazol-1-yl)acetate (bpza) or bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza), have been synthesized and characterized by spectral (IR, ¹H, ¹³C and ¹¹⁹Sn NMR, ^119mSn Mössbauer) and analytical data. In [SnI₃(bdmpza)], the ligand is fac-N,N′,O-tridentate, the three iodine atoms thus also fac about the six-coordinate tin(IV) atom. Neutral bpzaH reacts with BuⁿSnCl₃, PhSnCl₃ and SnCl₄ in Et₂O in the absence of base, yielding 1:1 adducts [XSnCl₃(bpzaH)] (X = R or Cl).     

Complex formation equilibria between Ag(I) and thioureas in n-propanol

Complex formation equilibria between Ag(I) and thiourea or N-alkyl-substituted thioureas have been investigated in n-propanol by potentiometry at 10 °C intervals from 5 to 50 °C. Stepwise formation of tris-coordinated AgL_n (n = 1-3) complexes has been found for the majority of the ligands. ΔH and ΔS values for the complex formation reactions have been evaluated from the dependence of ln β_n on temperature. The alkyl-substituents affect the ligand affinities in different ways in relation with the coordination level n.The reactions are exothermic with few exceptions. Enthalpy favoured complex formation with negative dependence of ΔG on temperature (ΔS > 0) have been found.The enthalpy and entropy changes for the stepwise complex formation equilibria are correlated by two linear compensative relationships with the same isoequilibrium temperature 50-51 °C.     

Electrochemical and bioelectrocatalytical properties of novel block-copolymers containing interacting ferrocenyl units

The electrochemical characterization of three different polystyrene-b-polybutadiene block-copolymers, functionalized with diferrocenylsilane units, is reported. The PB-blocks have been functionalized with different fractions of electronically communicated, PS_m-PB_n−p (HSiMeFc₂)_p units, where m = 615, n = 53, p = 39 (1), m = 375, n = 92, p = 76 (2) and m = 455, n = 204, p = 170 (3). Electrochemical characterization has been carried out both in solution and after electrochemical deposition onto platinum electrodes. The bioelectrocatalytical properties of electrodes modified with the polymers in the nicotinamide dinucleotide (NADH) and glucose oxidase (GOx) oxidations have been investigated as a function of the constitution and structure of the polymers. The analytical properties of electrodes modified with these polymers as sensors of NADH and GOx are described. In addition, an amperometric biosensor for glucose, prepared by electrostatic immobilization of glucose oxidase onto a platinum electrode modified with one of the ferrocenyl block-copolymers as an example, has been developed.     

Synthesis and characterization of organophosphine/phosphite stabilized silver(I) methanesulfonates: Crystal structures of [Ph3PAgO3SCH3] and [(Ph3P)2AgO3SCH3]

Six organophosphine/phosphite stabilized silver(I) methanesulfonates of type [L_nAgO₃SCH₃] (L = Ph₃P, n = 1, 2a; n = 2, 2b; n = 3, 2c; L = (EtO)₃P; n = 1, 2d; n = 2, 2e; n = 3, 2f) were synthesized by the reaction of silver methanesulfonates with triphenylphosphine or triethylphosphite in dichloromethane under nitrogen atmosphere. These complexes were obtained in high yields and characterized by elemental analysis, ¹H-, ¹³C{H} NMR, IR spectroscopy and thermogravimetric analysis (TGA), respectively. X-ray single crystal analysis reveals that complex 2a is a tetramer [Ph₃PAgO₃SCH₃]₄ and complex 2b is a monomer. The thermal stability of 2a has been studied by applying thermogravimetric analysis. It starts to decompose between 50 and 440 °C in a three-step process. The final residue (Ag) is about 20.50%.     

The electronic structures of all trans form of permethyl-oligosilane radical cation with longer chain: A density functional theory study

Hybrid density functional theory (DFT) calculations have been carried out for neutral, radical cation and dication of permethyl-oligosilane, Si_n(CH₃)_2n+2 (n = 4-30), to elucidate the electronic structures at ground and low-lying excited states. It was found that a hole is distributed in both the Si-Si skeleton (main chain) and methyl group (side chain) in the case of shorter chain-lengths below n = 6, whereas the spin density (hole) in the methyl group becomes significantly smaller in longer chain-lengths (n > 7). The IR-band of radical cation were assigned on the basis of theoretical calculations.