Glow discharge polymerization in the mixture of tetramethylsilane and ammonia gas

Colorless, transparent, and filmy polymers prepared from mixtures of tetramethylsilane (TMS) and ammonia gas (NH₃) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. These polymers contained a large amount of nitrogen residues in the form of amine, amide, and amine oxide groups. Their concentration varied with the composition of the starting TMS/NH₃ mixtures. The mixing of NH₃ gas with TMS influenced the chemical state of Si residues and accelerated the oxidation of Si atoms to form silicon oxides such as SiO, Si₂O₃, and SiO₂. The polymers formed by glow discharge polymerization in the TMS/NH₃ mixtures were combinations of Si- and N-containing polymers and silicon oxides.     

Glow discharge polymerization of tetramethylgermanium

A glow discharge polymerization technique was applied in the preparation of germanium-containing polymers. The colorless and transparent polymer films formed from tetramethylgermanium (TMG) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. The reaction of TMG was accompanied by the rupture of bonds between Ge and CH₃ groups which led to mixtures of polymers that consisted of CH₃, CH₂, Ge? CH₃, Ge? O? C, and Ge? O? Ge groups and germanium metal. Most Ge species present at the outermost layers of the films were oxidized subsequently by air, whereas the Ge species at the inner layers still existed as Ge metal. This film-forming process can be explained by the concept of atomic polymerization proposed by Yasuda.

1 See H. Yasuda, J. Polym. Sci. Macromol. Rev., 16 , 199 (1981).

     

Glow discharge polymerization of tetramethylsilane investigated by infrared spectroscopy and ESCA

The influence of operating conditions (W/FM parameter: W input energy of rf power; F flow rate of monomer; M molecular weight of monomer) on glow discharge polymerization of tetramethylsilane (TMS) was investigated by infrared spectroscopy and ESCA. Elemental analyses showed that the compositions of the polymers formed strongly depended on the level of the W/FM parameter, i.e., whether the W/FM value was more or less than 190 MJ/kg. The infrared spectra indicated that these polymers were composed of Si? H, Si? O, Si? C, Si? CH₃, and Si? CH₂ groups, and that there was no significant difference in structural features between polymers prepared at W/FM parameters of more or less than 190 MJ/kg. ESCA spectra (C_1s and Si_2p core-level spectra) showed that the polymers included carbonized carbon, aliphatic carbon Si? C, C? O, Si? O, and SiO₂ species, and that the sum of carbonized and aliphatic carbons reached more than 50%. Raising the W/FM value increased the formation of the carbonized carbon but did not influence the formation of Si units such as Si? C and Si? O groups. From this evidence the rupture of Si? CH₃ bonds in the polymer forming process is emphasized. The magnitude of the W/FM parameter may be related to the detachment of hydrogen from the aliphatic carbon units.     

Diorganotin(IV) bis(O,O-alkylenedithiophosphates)

O,O-Alkylenedithiophosphates of diorganotin(IV) of the type R₂Sn[SP(S)O₂G]₂ (R = Me, Et, n-Bu, Ph; G = CH₂CMe₂CH₂, CMe₂CMe₂, CMe₂CH₂CHMe) have been synthesized by the reactions of diorganotin(IV) dichlorides with ammonium O,O-alkylenedithiophosphates or that of diorganotin(IV) oxides with O,O-alkylenedithiophosphoric acids in 1:2 molar ratio in benzene. These new complexes are white solids which are soluble in common organic solvents and are monomeric in refluxing benzene; and they have been characterized by elemental analysis and by different spectroscopic (IR, ¹H, ¹³C, ³¹P and ¹¹⁹Sn NMR) studies, on the basis of which a six coordinated octahedral structure has been suggested in solution.     

Skew-trapezoidal bipyramidal diorganotin(IV) bischelates. Crystal structure of dimethylbis(2-pyridinethiolato-N-oxide)tin(IV)

Dimethylbis(2-pyridinethiolato-N-oxide)tin(IV), Me₂Sn(2-SPyO)₂, crystallizes in space group P2₁/c with a 9.877(3), b 11.980(4), c 13.577(3) Å, β 109.1(2)° and Z = 4. The structure was refined to R_F = 0.036 for 2263 Mo-K_α observed reflections. The coordination geometry at tin is a skew-trapezoidal bipyramid, with the oxygen [SnO 2.356(3), 2.410(4) Å] and sulfur [SnS 2.536(1), 2.566(1) Å] atoms of the chelating groups occupying the trapezoidal plane and the methyl groups [SnC 2.106(6), 2.128(7) Å] occupying the apical positions. The methyl-tin-methyl skeleton is bent [CSnC 138.9(2)°]. The SSnS angle is 77.8(1)°, but the OSnO angle is opened to 136.7(1)° to accommodate the intruding methyl groups. The carbontincarbon angles predicted from quadrupole splitting (^119mSn Mössbauer) and one-bond ¹¹⁹Sn¹³C coupling constant (solution ¹³C NMR) data agree closely with the experimental value.     

Plasma polymerization of fluoromethanes

Methane and fluoromethanes (CH_nF_4−n, 1 ≤ n ≤ 3) were subjected to an rf glow discharge plasma. All the fluoromethanes (including methane) polymerized in the plasma and formed thin films. The deposition rate of the fluoromethanes depended on their monomer structure: CH₂F₂, of which the F/H ratio is unity, showed the greatest deposition rate. The elimination of H and F atoms as H—F was found to be a key factor for the polymerization of fluoromethanes. The chemical composition of the polymerized film, measured with X-ray photoelectron spectroscopy and glow discharge emission spectroscopy, was also found to be strongly dependent on monomer structure. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2043–2050, 1998     

Etude structurale de composes organosilicies par diffusion rayleigh depolarisee : V. Proprietes acceptrices d'electrons du silicium dans les systemes SiOC et SiOSi

Among the characteristic properties of the SiOC and SiOSi systems relative to those of the corresponding COC systems, the optical anisotropy is a new example which shows the electron-acceptor ability of silicon by (p → d)π interaction in compounds of the type R₃SiO∑ (R = Me, Et, Pr; ∑ = H, Me, SiMe₃, CH₂-t-Bu, CHMe₂, CMe₃). Effectively, the existence of a linear relationship between the optical anisotropy or the principal optical polarisabilities of the OSiR₃ groups and the Taft's parameter σ^★ of the ∑ groups in this series of compounds, shows that the electron-accepting character of silicon increases with increasing electron-donating ability of the group ∑; this relationship simultaneously translates an increase of the electronic density and mobility perpendicular to the OSi axis to the detriment of the parallel direction. In application, we calculated the σ^★ values for the groups ∑ = SiEt₃, SiPr₃ and the OSiMe₃ optical anisotropy value in PhOSiMe₃.     

Cleavage of benzyltrimethylstannanes by aqueous methanolic perchloric acid

The rates of cleavage of some XC₆H₄CH₂SnMe₃ bonds by aqueous-methanolic perchloric acid have been measured spectrophotometrically, and the rate of cleavage of the MeSn bonds of PhCH₂SnMe₃ and Me₄Sn by monitoring the methane evolution. The results indicate that for X = H, p-Me, o-Me, p-Bu^t, o-, m- and p-F and -Cl, and o-Br, the cleavage of the CH₂SnMe₃ bond involves attack of the acid at the benzylic atom, and is not much faster than that of the SnMe bonds, but that a mechanism involving ring-protonation is important for X = m-Me, and greatly predominant for X = m-OMe.     

Some reactions of tris(trimethylstannyl)- and tetrakis(trimethylstannyl)-methane

With a variety of electrophilic reagents reaction occurs exclusively at the CH₃Sn bonds of [(CH₃)₃Sn]₄C and [(CH₃)₃Sn]₃CH. While the inner SnC bonds remain intact, methyl groups may be progressively cleaved off, one from each of the trimethylstannyl groups; in the case of bromine a second Me group may be cleaved from each of the SnMe₂Br groups. The various products were identified by ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy.     

ESR Study of the Plasma Polymerizations of Trimethylsilane and Methane

Electron Spin Resonance (ESR) was used to study, at the molecular level, the plasma polymerization of trimethylsilane (TMS) and methane. Direct ESR analysis of the plasma coated Al substrate required the use of a novel ESR technique. TMS plasma deposit on Al showed a single broad resonance line near g = 2.003. The signal was stable in vacuum and decayed on exposure to air, with a significant fraction persisting for days. Results show that this signal arises from silicon dangling bonds. Identical TMS signals were observed from films prepared by the DC cathodic or the AF glow discharge method but their decay rates were different. In contrast, the deposition of methane produced two distinct types of carbon-based signals depending upon the method of deposition. TMS or CH₄ films deposited by the DC cathodic method showed slow signals decay and high refractive indices value. While the use of Al as the substrate showed plasma-coating radicals, only substrate radicals were observed when PE was used as the substrate. The nature of radicals formed depends not only on the deposition method used but also on the substrate type.     

Compounds containing CSF4 and CS+F4

The preparations of CH₂SF₄ and CH₃CHSF₄ are presented and the structures are discussed. Addition reactions of polar species give a wide range of new compounds, like Hg(CH₂SF₅)₂, F₄AsCH₂SF₅, cisBrSF₄CH₃, cisF₅SeOSF₄CH₂Br, a.o. While CH₂SF₄ decomposes at room temperature slowly to CH₂CH₂ and SF₄, at high temperatures HF and CSF₂ are formed. CH₃CHSF₄ gives mainly CH₃CHF₂ at room temperature. The “saturated” compounds CH₃SF₅ and C₂H₅SF₅ have been prepared. They react with SbF₅ in SO₂ at low temperatures to form the cations CH₃SF₄⁺ and C₂H₅SF₄⁺. The CH₃SF₄⁺ ion has been investigated in detail by nmr methods at low temperatures. It decomposes to CH₃ and SF₄, which react further in the SO₂/SbF₅ system to CH₃OSO⁺ and SF₃⁺.     

Methane separation by a continuous membrane column

A continuous membrane column was employed to separate methane from gas mixtures of CO₂CH₄, CH₄N₂ and CO₂CH₄ N₂ at room temperature. Shell-side composition profiles along the column were taken experimentally and compared with the calculated results. The agreements were excellent, indicating that the model calculation is adequate for a ternary system. Combination of two columns was developed to separate the ternary mixture.     

Vapour—liquid equilibrium at elevated pressures from the perturbation theory. II. Binary systems

Vapour—liquid equilibria in binary systems of non-polar non-spherical molecule compounds were studied theoretically by combining the perturbation theory of convex molecule fluids with a new variant of the conformal solution theory. The recently proposed equation of state of hard convex body mixtures and the corresponding expressions for the contact values of distribution functions were employed to determine the reference thermodynamic functions and the perturbation terms. Ten binary systems, i.e. ArCH₄, N₂CH₄, N₂C₂H₄, N₂C₂H₆, CH₄C₂H₄, CH₄C₂H₆, C₂H₄C₂H₆, CO₂C₂H₄, CO₂C₂H₆, and ArCO₂ were studied at constant temperatures. Comparison of theoretical predictions with experimental data is given.     

Pulsed fourier transform NMR of substituted aryltrimethyltin derivatives : III. Proton data at 100 MHz and the derived Hammett σ-constant of the trimethyltin group

Proton NMR data at 100 MHz are reported for thirteen para- and meta-substituted phenyltrimethyltin compounds, XC₆H₄Sn(CH₃)₃, where X = para-N(CH₃)₂, para-OCH₃, para-OC₂H₅, para-CH₃, meta-CH₃, -H, para-F, meta-OCH₃, para-Cl, para-Br, meta-F, meta-Cl and para-Sn(CH₃)₃. Correlation coefficients with Hammett σ-constants of greater than 0.95 are obtained with the methyltin proton chemical shifts and coupling constants to carbon [¹J(¹³C¹H)] and tin [²J(SnC¹H)]. Solvent effects and other extraneous factors invalidate comparisons of ? values in terms of the relative attenuation of the transmission of substituent effects through homologous carbon, silicon, germanium and tin systems, but coupling constant data reflect a diminution of ca. one tenthfold per bond in the order ?[C(1)Sn] > ? [SnC] > ? [CH]. Satisfactory correlations (r > 0.95) are obtained in this series of closely-related compounds among the conventionally recorded two-bond, ²J(SnC¹H) and the constituent, one-bond ¹J (Sn¹³C) and J(¹³C¹H) coupling constants, but the correlation coefficient for the comparison between the two one-bond couplings, ¹J(Sn¹³C) and ¹J(¹³C¹H) is lower (r = 0.872). Changes in the couplings at the methyltin carbon bond tin-119 atoms are interpreted in terms of isovalent hybridization; a model based upon effective nuclear charges is tested with respect to both NMR coupling constants and ¹¹⁹Sn Mössbauer Isomer shifts at tin and is invalidated. Proton and carbon-13 NMR, chemical shift and coupling constant data are used to derive a Hammett σ-constant for the para-trimethyltin group of ?0.14, and the significance of this value is discussed.     

Comparisons of glow discharge polymerization between hexamethyldisilazane and trimethylsilyldimethylamine

Glow discharge polymerization between hexamethyldisilazane (HMDSZ) and trimethylsilyldimethylamine (TMSDMA) was compared by means of infrared spectroscopy and ESCA analysis. Infrared spectra pointed out differences in chemical structure between the polymers prepared from the two monomers, although the two polymers were mainly composed of resembling units such as Si? CH₃, Si? CH₂, Si? H, Si? O? Si, and Si? O? C groups: (i) The polymers prepared from TMSDMA contained N → O group, but the polymers from HMDSZ did not contain this group. (ii) Influences of the W/FM parameter (W is the input energy of rf power, F the flow rate of the monomer, and M the molecular weight of the monomer) appeared on decreasing the C? N group and increasing the C?O group in the TMSDMA system, but little influence appeared in the HMDSZ system. ESCA spectra (C_1s, Si_2p, and N_1s core levels) supported the differences between the two polymers elucidated by infrared spectroscopy, and pointed out differences in susceptibility of the Si? N bond to plasma: The N? Si sequence of TMSDMA was completely ruptured in discharge to yield polymers, and the Si? NH? Si sequence of HMDSZ remained in considerable amount.     

Matrix Isolation and IR spectroscopy of stannylenes (CH3)2Sn and (CD3)2Sn

Free stannylenes Me₂Sn and (CD₃)₂Sn, generated thermally from the cyclic hexamers or by microwave discharge from Me₂SnH₂, are isolated by Argon matrix technique. All IR bands could be attributed to the important molecular vibrations by normal coordinate analysis. As shown by ab initio SCF calculations, Me₂Sn has a singlet groud state, the angle CSnC is 95.3°, the CSn bond length is 2.203 Å.     

Far-infrared studies of ethanols and fluoroethanols trapped in low-temperature matrices

Ethanol, its deuterated derivatives (C₂H₅OD, C₂D₅OD) and fluoroethanols (CFH₂CH₂OH, CF₃CH₂OH) have been isolated in low temperature matrices and investigated in the far-infrared region. From the concentration dependency of the observed bands and from studies of the pure alcohols in the gaseous, liquid, and solid phase it was found that the hydrogen bond stretching frequencies ν_σ associated with the hydrogen bonded system OH?O appear in the 100 – 160 cm^?1 range. At higher M/A ratios the OD(OD) torsion modes τ_OH are dominating and were identified in the 200 – 300 cm^?1 region. The influence of various matrix materials like argon, krypton, xenon, nitrogen and methane on the low frequency spectra of ethanol have also been studied. It was found, that nitrogen and methane matrices produce significant changes in the far infrared spectra.     

Analysis of the antitarnish film on a tin surface by x-ray photoelectron spectroscopy and Auger electron spectroscopy

A corrosion-resistant complex film formed in ethylenediaminetetra(methylidenephosphonic acid) (EDTMP) solution was determined by x-ray photoelectron spectroscopy and Auger electron spectroscopy to consist of 48.0% O, 11.7% Sn, 7.7% N, 22.1% C and 10.5% P. From the differences in the binding energies of Sn, N and O before and after film formation and the RPO^2?₃ and SnN vibrations in the Raman spectrum of the film, it was deduced that N and O in EDTMP were coordinated with Sn in the film.     

The molecular structure of the complex trimethylaluminium dimethyl ether, (CH3)3AlO(CH3)2, determined by gas phase electron diffraction

The molecular structure of (CH₃)₃AlO(CH₃)₂ has been determined by gas phase electron diffraction. The main molecular parameters are AlC = 1.973(11), AlO = 2.014(14), OC = 1.436(3) Å, OAlC = 98.7(1.5), AlOC = 122.6 (0.5) and COC = 114.5(1.7)°. The OC bond distance and the COC valence angle are significantly larger than those in free dimethyl ether. The three valencies of the oxygen atom appear to lie in one plane. It is suggested that the planarity of the oxygen atom is due to across-angle repulsion Al?C(O).     

Gel formation in cationic polymerization of divinyl ethers. I. 1,4-Bis(2-vinyloxyethoxy)benzene

Polymerization of 1,4-bis(2-vinyloxyethoxy)benzene (CH₂C O CH₂ CH₂ O C₆H₄ O CH₂CH₂ O CCH₂; 1 ) was investigated in CH₂Cl₂ at 0°C with the use of a variety of cationic initiators. SnCl₄, SnBr₄, AlEtCl₂, and BF₃OEt₂ (strong Lewis acids) and CF₃SO₃H (a strong protonic acid) yielded crosslinked insoluble polymers immediately after the polymerizations were initiated. The binary initiating systems such as HCl/ZnCl₂ and (C₆H₅O)₂P(O)OH/ZnCl₂ also produced insoluble poly( 1 )s. At the low initial concentration of ZnCl₂, however, the (C₆H₅O)₂P(O)OH/ZnCl₂ system gave the soluble polymers quantitatively, and gelation occurred only when the reaction mixture was stored for a long time after complete consumption of the monomer. The content of the unreacted pendant vinyl ether groups of the soluble polymers decreased with monomer conversion, and almost all the pendant vinyl ether groups were consumed in the soluble polymer obtained at 100% monomer conversion; this may be ascribed to frequent occurrence of intramolecular crosslinking. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 675–683, 1998