Consecutive reactions of diethoxydimethylsilane and triethoxymethylsilane with methoxide ions in methanol solution

The consecutive reactions of (CH₃)₂Si(OC₂H₅)₂ and CH₃Si(OC₂H₅)₃ with methoxide ions were investigated in methanol solutions. The reverse transesterification reactions with ethoxide ions could be neglected in both cases since the concentration of ethoxide in methanol solution was assumed to be low due to the fast equilibrium reaction C₂H₅O^? + CH₃OH ? C₂H₅OH + CH₃O^?. The progress of the reactions was followed by monitoring the formation of ethanol with a Fourier-transform infrared spectrometer. All rate constants were determined at 295 K. The reactions between the dialkoxydimethylsilanes and methoxide ions were assumed to consist of two consecutive steps that can be represented by the net reaction; (CH₃)₂Si(OC₂H₅)₂ + 2CH₃O^? → (CH₃)₂Si(OCH₃)₂ + 2C₂H₅O^?. The two consecutive rate constants were established as 1.93 ± 0.12M^?1s^?1 and 1.00 ± 0.12M^?1s^?1, respectively. The consecutive rate constants for the reactions between the trialkoxymethylsilanes and methoxide ions can be written according to the total reaction; CH₃Si(OC₂H₅)₃ + 3CH₃O^? → CH₃Si(OCH₃)₃ + 3C₂H₅O^?. The three rate constants corresponding to each consecutive step were established as 1.12 ± 0.09 M^?1s^?1, 0.82 ± 0.10 M^?1s^?1, and 0.51 ± 0.06 M^?1s^?1, respectively. © 1995 John Wiley & Sons, Inc.     

Reactions and properties of some trimethyleneplatinum(IV) complexes: X. Reaction with iodide and thiocyanate ions

The reaction between the platinacyclobutanes [$\text{PtX}{}_2\text{(CH}{}_2\text{CRR′C}$H₂)L₂] (X  Cl, Br; L  C₅H₅N, 4-CH₃C₅H₄N; R, R′  H, CH₃; R  H, R′  CH₃, C₆H₅) and iodide and thiocyanate ions in methyl cyanide solution has been studied. The C₃ moiety is eliminated as the cyclopropane and the process is first order with respect to the platinacyclobutanes and zero to half order with respect to the salt (MY). With the iodides the rate increases in the order Li < Na < K, Et₄N, and methyl substitution in the cyclobutane ring reduces the rate of reaction with Et₄NI. Added pyridine retards the reaction when L  C₅H₅N (X  Cl; R, R′  H) and added dimethylsulphoxide accelerates it.The mechanism suggested involves dissociation of an L ligand and attack of Y^? ions and of M⁺Y^? ion pairs on the five-coordinate intermediate formed.     

Kinetics and mechanism of atmospheric reactions of partially fluorinated alcohols

Gas-phase reactions typical of the Earth’s atmosphere have been studied for a number of partially fluorinated alcohols (PFAs). The rate constants of the reactions of CF₃CH₂OH, CH₂FCH₂OH, and CHF₂CH₂OH with fluorine atoms have been determined by the relative measurement method. The rate constant for CF₃CH₂OH has been measured in the temperature range 258–358 K (k = (3.4 ± 2.0) × 10¹³exp(?E/RT) cm³ mol^?1 s^?1, where E = ?(1.5 ± 1.3) kJ/mol). The rate constants for CH₂FCH₂OH and CHF₂CH₂OH have been determined at room temperature to be (8.3 ± 2.9) × 10¹³ (T = 295 K) and (6.4 ± 0.6) × 10¹³ (T = 296 K) cm³ mol^?1 s^?1, respectively. The rate constants of the reactions between dioxygen and primary radicals resulting from PFA + F reactions have been determined by the relative measurement method. The reaction between O₂ and the radicals of the general formula C₂H₂F₃O (CF₃CH₂? and CF₃?HOH) have been investigated in the temperature range 258–358 K to obtain k = (3.8 ± 2.0) × 10⁸exp(?E/RT) cm³ mol^?1 s^?1, where E = ?(10.2 ± 1.5) kJ/mol. For the reaction between O₂ and the radicals of the general formula C₂H₄FO (? HFCH₂O, CH₂F?HOH, and CH₂FCH₂?) at T = 258–358 K, k = (1.3 ± 0.6) × 10¹¹exp(?E/RT) cm³ mol^?1 s^?1, where E = ?(5.3 ± 1.4) kJ/mol. The rate constant of the reaction between O₂ and the radicals with the general formula C₂H₃F₂O (?F₂CH₂O, CHF₂?HOH, and CHF₂CH₂?) at T = 300 K is k = 1.32 × 10¹¹ cm³ mol^?1 s^?1. For the reaction between NO and the primary radicals with the general formula C₂H₂F₃O (CF₃CH₂? and CF₃?HOH), which result from the reaction CF₃CH₂OH + F, the rate constant at 298 K is k = 9.7 × 10⁹ cm³ mol^?1 s^?1. The experiments were carried out in a flow reactor, and the reaction mixture was analyzed mass-spectrometrically. A mechanism based on the results of our studies and on the literature data has been suggested for the atmospheric degradation of PFAs.     

Spektroskopische Untersuchungen an Siliciumverbindungen. XXXI. Schwingungsverhalten von p-substituierten N,N-Bistrimethylsilylanilinen

The following p-substituted N,N-bis-trimethlsilyl anilines p-X? C₆H₄? N[Si(CH₃)₃]₂ are prepared by silylation of free amines: X = H, CH₃, C₂H₅, CH₃O, CH₃CO, F, Cl, Br, J, CN, C₆H_S, (CH₃)₃SiO, and [(CH₃)₃Si]₂N, and the isotopic derivatives C₆H₅? ¹⁵N[Si(CH₃)₃]₂ and C₆D₅N[Si(CH₃)₃]₂. The vibrational spectra are reported and assigned. The molecular symmetry of p-[(CH₃)₃Si]₂N? C₆H₄? N[Si(CH₃)₃]₂ is determined. The influence of the mass of the substituents X on the positions of the ν_sSiNSi vibrational frequencies is discussed.     

KINETIC STUDIES OF LEWIS BASE ADDITION TO CpFe(CO)(η3-CH2C6H4-p-X); X = OMe,Me, H,F, Cl,Br

Abstract

Kinetic studies illuminate details of the reaction of photoproduced CpFe(CO)(η³-CH₂C₆H₅) with two electron Lewis bases. Rate constants of 151(10)M^?1s^?1 for CO back reaction and between 440 and 3200 M^?1s^?1 for reaction with various phosphine nucleophiles were recorded. Linear free energy analysis quantifies the stereoelectronic effect of the nucleophile. Variation of the para-substituent on the benzyl group demonstrates that an electron rich benzyl group impedes reaction. The effect of ancillary ligands was seen by substitution of C₅Me₅ for C₅H₅. The large, electron rich C₅Me₅ speeds up CO substitution but slows down PPh₃ substitution. Mechanistic clues were obtained from Eyring plots for reaction of CpFe(CO)(η³-CH₂C₆H₅) with 4 different phosphines. Examination of the measured enthalpy and entropy barriers suggests a stepwise reaction mechanism.     

Transition-metal mediated heteroatom removal by reactions of FeL+ [L=O,C4H6, c-C5H6, c-C5H5, C6H6, C5H4(=CH2)] with furan,thiophene, and pyrrole in the gas phase

Reactions of Fe⁺ and FeL⁺ [L=O, C₄H₆, c-C₅H₆, C₅H₅, C₆H₆, C₅H₄(=CH₂)] with thiophene, furan, and pyrrole in the gas phase by using Fourier transform mass spectrometry are described. Fe⁺, Fe(C₅H₅)⁺, and FeC₆H ₆ ⁺ yield exclusive rapid adduct formation with thiophene, furan, and pyrrole. In addition, the iron-diene complexes [FeC₄H ₆ ⁺ and Fe(c-C₅H₆)⁺], as well as FeC₅H₄(=CH₂)⁺ and FeO⁺, are quite reactive. The most intriguing reaction is the predominant direct extrusion of CO from furan by FeC₄H₆ ⁺, Fe(c-C₅H₆)⁺, and FeC₅H₄(=CH₂)⁺. In addition, FeC₄H ₆ ⁺ and Fe(c-C₅H₆)⁺ cause minor amounts of HCN extrusion from pyrrole. Mechanisms are presented for these CO and HCN extrusion reactions. The absence of CS elimination from thiophene may be due to the higher energy requirements than those for CO extrusion from furan or HCN extrusion from pyrrole. The dominant reaction channel for reaction of Fe(c-C₅H₆)⁺ with pyrrole and thiophene is hydrogen-atom displacement, which implies D^O(Fa(N₅H₅)⁺-C₄H₄X)>D^O(Fe(C₅H₅)⁺-H)=46±5 kcal mol^?1. D^O(Fe⁺-C₄H₄S) and D^O(Fe⁺-C₄H₅N)=D^O(Fe⁺-C₄H₆)=48±5 kcal mol^?1. Finally, 55±5 kcal mol^?1=D^O(Fe⁺-C₆H₆)>D^O(Fe⁺-C₄H₄O)>D^O(Fe⁺-C₂H₄)=39.9±1.4 kcal mol^?1. FeO⁺ reacts rapidly with thiophene, furan, and pyrrole to yield initial loss of CO followed by additional neutral losses. D^O(Fe⁺-CS)>D^O(Fe⁺-C₄H₄S)≈48±5 kcal mol^?1 and D^O(Fe⁺-C₄H₅N)≈48±5 kcal mol^?1>D^O(Fe⁺-HCN)>D^O(Fe⁺-C₂H₄)=39.9±1.4 kcal mil^?1.     

Stereoselektive Hydrid-Addition an von N-Methylbenzimidchlorid abgeleitete Carbenchelatkomplexe

Upon reaction with NaBH₄ the carbene chelates [C₅H₅(CO)_xMC(C₆H₅N(CH₃)C(C₆H₅)N(CH₃)]PF₆ (I,M = Mo, x = 2; II,M = Fe, x = 1) are reduced at the carbene carbon with formation of the neutral compounds C₅H₅(CO)_xMC(H)(C₆H₅)N(CH₃)C(C₆H₅)N(CH₃) (III and IV). Depending on the orientation of the incoming H substituent with respect to the C₅H₅ ligand two different isomers A and B are obtained which can be separated by column chromatography. Whereas the H^? addition to the Fe compound II is almost stereospecific (formation of 95% IVB), the stereoselectivity of the H^? addition to the Mo compound I is influenced by a competitive metal centered rearrangement of III in opposite direction. The approach to the equilibrium IIIA/IIIB 85/15 can be measured by ¹H NMR spectroscopy (ΔG³₃₂₈ 26.6 kcal/mol).     

Kinetische und mechanistische untersuchungen von übergangsmetallkomplex-reaktionen : VI. Kinetik und mechanismus der einschiebung von dimethylcyanamid in die metall—carbenkohlenstoff-bindung von pentacarbonyl(arylphenylcarben)wolfram

Pentacarbonyl(arylphenylcarbene)tungsten complexes, (CO)₅W[C(p-C₆H₄R)C₆H₅] (Ia, R = OCH₃; Ib, R = CH₃; Ic, R = H; Id, R = Br; Ie, R = CF₃) react with dimethylcyanamide (II) via insertion of the CN group into the metalcarbene bond. The formation of pentacarbonyl[dimethylamino(imino)carbene]tungsten(0) (IIIa–IIIe) follows a second-order rate law: d[III]/dt = k[I][II]. Replacement of R = H by electron-withdrawing substituents (Br, CF₃) results in an increase, by electron-donating groups (CH₃, OCH₃) in a decrease of the reaction rate. The rate constants correlate well with Hammett's σ-constants. The activation enthalpies ΔH^≠ are low (37.3–41.6 kJ mol^?1), the activation entropies ΔS^≠ strongly negative (?119 to ?133 J mol^?1 K^?1). The results are discussed on the basis of an associative stepwise mechanism with a nucleophilic attack of the CN group of II at the carbene carbon in the first reaction step.     

Photodecomposition reaction of ethyl bromide at 147 nm

A vacuum ultraviolet photolysis of C₂H₅Br at 147 nm was studied over a pressure range of 0.5–50 torr at 298 K. The effects of additives He and NO were also investigated. The principal reaction products were found to be C₂H₄ and C₂H₆, with lesser yields of CH₄ and C₂H₂. With increasing pressure the product quantum yields Φ_i of C₂H₄, CH₄, and CH₂H₆ remained constant, while that of C₂H₂ decreased from 0.03 to almost 0. The effect of He as an additive was found to be extremely small on the quantum yields of the major products. Addition of NO completely suppresses the formation of CH₄, C₂H₂, and C₂H₆, and reduces partially the production of C₂H₄. The primary processes appear to involve two electronically excited states. One state mainly yields C₂H₄ by molecular elimination of HBr and is thought to be due to a Rydberg transition. The other state decomposes to C₂H₅ and Br radicals by C? Br bond fission. These two competitive reaction modes contribute to the photodecomposition in proportions of 50% and 50%. The extinction coefficient for C₂H₅Br at 147 nm and at 298 K has been determined as ? = (1/PL) In(I_o/I_t) = 712 ± 7 atm^?1 · cm^?1.     

Synthese und strukturelle Charakterisierung von Borsubphthalocyaninaten

Synthesis and Structural Characterization of Boron Subphthalocyaninates Halosubphthalocyaninatoboron, [B(X)_spc] (X = F, Cl, Br) is obtained by heating phthalonitrile with boron trihalide in quinoline (X = F) or the corresponding halobenzene, resp. [B(C₆H₅)_spc] is prepared from phthalonitrile and tetraphenylborate or tetraphenyloboron oxide, resp. [B(OR)_spc] (R = H, CH(CH₃)₂, C(CH₃)₃, C₆H₅) is synthesized by bromide substitution of [B(Br)_spc] in pyridine/HOR. Substitution of [B(Br)_spc] in carboxylic acids yields [B(OOCR)_spc] (R = H, CX₃ (X = H, Cl, F), CH₂X (X = Cl, C₆H₅), C₆H₅). All subphthalocyaninates are characterized electrochemically and by UV‐VIS, IR/FIR, resonance Raman, and ¹H/¹⁰B‐NMR spectroscopy. Typical B–X stretching vibrations are at 622 (X = Br), 950 (Cl), 1063 (F), 1096 cm^–1 (OH) as well as between 1119 and 1052 cm^–1 (OR) resp. 985 and 1028 cm^–1 (OOCR). The difference ν(C=O)–ν(C–O) > 400 cm^–1 confirms the unidentate coordination of the carboxylato ligands. According to the crystal structure analysis of [B(OH)_spc], [B(OH)_spc] · 2 H₂O, [B(C₆H₅)_spc], [B(OC(CH₃)₃)_spc], [B(OOCCH₃)_spc] · 0.5 H₂O · C₂H₅OH and [B(OOCCH₃)_spc] · 0.4 H₂O · 1.1 C₅H₅N the _spc ligand is concavely distorted. This saucer shaped conformation is independent of the acido ligands and the presence of solvate. The outermost C atomes are vertically displaced in part by more than 2 Å from the N_i plane. The B atom is in a distorted tetrahedral coordination geometry. It is displaced by ca 0.64 Å out of the N_i plane towards the acido ligand. The average B–N distance is 1.500 Å, and the B–O distances range from 1.418(5) to 1.473(2) Å.     

Thermochemical study of [Sm(C7H5O3)2·(C4H6NO2S)]·2H2O

The product from reaction of samarium chloride hexahydrate with salicylic acid and Thioproline, [Sm(C₇H₅O₃)₂·(C₄H₆NO₂S)]·2H₂O, was synthesized and characterized by IR, elemental analysis, molar conductance, and thermogravimetric analysis. The standard molar enthalpies of solution of [SmCl₃·6H₂O(s)], [2C₇H₆O₃(s)], [C₄H₇NO₂S(s)] and [Sm(C₇H₅O₃)₂·(C₄H₇NO₂S)·H₂O(s)] in a mixed solvent of absolute ethyl alcohol, dimethyl sulfoxide(DMSO) and 3 mol L^?1 HCl were determined by calorimetry to be Δ_s H _m ^Φ [SmCl₃ δ6H₂O (s), 298.15 K]= ?46.68±0.15 kJ mol^?1 Δ_s H _m ^Φ [2C₇H₆O₃ (s), 298.15 K]= 25.19±0.02 kJ mol^?1, Δ_s H _m ^Φ [C₄H₇NO₂S (s), 298.15 K]=16.20±0.17 kJ mol^?1 and Δ_s H _m ^Φ [Sm(C₇H₅O₃)₂·(C₄H₆NO₂S)]·2H₂O (s), 298.15 K]= ?81.24±0.67 kJ mol^?1. The enthalpy change of the reaction (1) $$ SmCl_3 \cdot 6H_2 O(s) + 2C_7 H_6 O_3 (s) + C_4 H_7 NO_2 S(s) = Sm(C_7 H_5 O_3 )_2 \cdot (C_4 H_6 NO_2 S) \cdot 2H_2 O(s) + 3HCl(g) + 4H_2 O(1) $$ was determined to be Δ_s H _m ^Φ =123.45±0.71 kJ mol^?1. From date in the literature, through Hess’ law, the standard molar enthalpy of formation of Sm(C₇H₅O₃)₂(C₄H₆NO₂S)δ2H₂O(s) was estimated to be Δ_s H _m ^Φ [Sm(C₇H₅O₃)₂·(C₄H₆NO₂S)]·2H₂O(s), 298.15 K]= ?2912.03±3.10 kJ mol^?1.     

Gas-phase reactions between O−. and C6H5F: On the acidity of fluorobenzene and 1,4-difluorobenzene

The gas-phase reactions of negative ions (O^-., NH ₂ ^? , C₂H₅NH^?, (CH₃)₂N^?, C₆H ₅ ^t- , and CH₃SCH ₂ ^? ) with fluorobenzene and 1,4-difluorobenzene have been studied with Fourier transform ion cyclotron resonance mass spectrometry. The O^?. ion reacts predominantly by (1) proton abstraction, (2) formal H ₂ ^+. abstraction, and (3) attack on an unsubstituted carbon atom. In addition to these processes, attack on a fluorine bearing carbon atom yielding F^? and C₆H₄FO^? ions occurs with 1,4-difluorobenzene. Site-specific deuterium labeling reveals the occurrence of competing 1,2-, 1,3-, and 1,4-H ₂ ^+. abstractions in the reaction of O^?. with fluorobenzene. Attack of the O^?. ion on the 3- and 4-positions in fluorobenzene with formation of the 3- and 4-fluorophenoxide ions, respectively, is preferred to reaction at the 2-position, as indicated by the relative extent of loss of a hydrogen and a deuterium atom in the reactions with labeled fluorobenzenes. The NH ₂ ^? , C₂H₅NH^?, (CH₃)₂N^?, C₆H ₅ ^? , and CH₃SCH ₂ ^? anions react with fluoroberuene and 1,4-difluorobenzene only by proton abstraction. The relative importance of H⁺ and D⁺ abstraction in the reaction of these anions with labeled fluorobenzenes indicates that the 2-position in fluorobenzene is more acidic than the 3- and 4-positions, suggesting that the literature value of the gas-phase acidity of this compound (ΔH _acid ^o = 1620 ± 8 kJ mol^?1) refers to the former site. Based on the occurrence of reversible proton transfer between the CH₃O^? ion and 1,4-difluorobenzene, the ΔH _acid ^o of this compound is redetermined to be 1592 ± 8 kJ mol^?1.     

Reactions of recoil bromine with bromochloromethanes

Reactions of recoil^{80, 80m}Br with CH₂ClBr and CCl₃Br have been investigated. Relative reactivities of recoil bromine atoms in binary mixtures of CH₂ClBr and CCl₃Br with c–C₆H₁₂, CH₃OH and C₆H₅N/CH₃/₂ have been determined using the model developed by Kontis and Urch.     

Minor processes in the photolysis of azomethane at low pressure: An upper limit for the rate of the unimolecular elimination of H2 from vibrationally excited ethane

The photolysis of azomethane in the near UV has been studied at room temperature and pressures from 10 mtorr to 10 torr. The main products, C₂H₆ and N₂, accounted for more than 99% of the reaction. Minor hydrocarbon products observed were (with quantum yields) C₃H₈ (3.5 × 10^?3), C₂H₄ (3.2 × 10^?4), CH₄ (3 × 10^?3), and n-C₄H₁₀ (trace). Quantum yields of H₂ of 4 × 10^?5 and 2 × 10^?5 were measured at azomethane pressures of 0.1 and 1.0 torr, respectively. The minor hydrocarbon products can be accounted for by reactions of CH₃ and C₂H₅ radicals following hydrogen abstraction from azomethane by CH₃. The H₂ product observed represents an upper limit for the H₂ elimination from vibrationally excited C₂H₆ formed by CH₃ combination in the system, corresponding to a rate of elimination ca. 5 × 10^?5 times the competing rate of dissociation to 2CH₃. Assuming a frequency factor of 10¹³ s^?1 for the H₂ elimination, a lower limit of about 90 kcal mol^?1 was estimated for the energy barrier.     

Organotin compounds bearing mesogenic sidechains: synthesis, X-ray structures and polymerisation chemistry

Organotin compounds R₃Sn(CH₂)_n+2OC₆H₄C₆H₄Y (R₃=Ph₃, Ph₂Bu; Y=H, CN; n=1-3) and RX₂Sn(CH₂)_n+2OC₆H₄C₆H₄Y (R=Ph, Bu; Y=H, CN; X=Br, I; n=1-3) have been synthesised and characterised by ¹H-, ¹³C-, ¹¹⁹Sn-NMR and Mössbauer spectroscopies. X-ray crystallography reveals tetrahedral geometries for Ph₃Sn(CH₂)₄OC₆H₄C₆H₅ and Ph₃Sn(CH₂)₃OC₆H₄C₆H₄CN, a six-coordinated, bromine-bridged dimeric structure for PhBr₂Sn(CH₂)₃OC₆H₄C₆H₅ containing a mer-Br₃C₂OSn coordination sphere about tin and a five-coordinated monomeric structure for PhBr₂Sn(CH₂)₃OC₆H₄C₆H₄CN. In all cases there is strong alignment of mesogenic groups in the solid-state but only PhBr₂Sn(CH₂)₃OC₆H₄C₆H₄CN shows any indication of liquid-crystal behaviour. Wurtz polymerisation of RBr₂Sn(CH₂)₅OC₆H₄C₆H₅ (R=Ph, Bu), both of which contain non-chelating ether functions, generated polystannanes (RR′Sn)_n with M_n 2.3×10⁵; M_w 3.0×10⁵; M_w/M_n 1.30 and M_n 1.3×10⁵; M_w 2.5×10⁵; M_w/M_n 1.96, respectively, while no polymer was obtained from chelated PhBr₂Sn(CH₂)₃OC₆H₄C₆H₅     

Kinetics and mechanism for the reactions of H atoms with CH3SH and C2H5SH

A kinetic study of the reactions of H atoms with CH₃SH and C₂H₅SH has been carried out at 298 K by the discharge flow technique with EPR and mass spectrometric analysis of the species. The pressure was 1 torr. It was found: k₁ = (2.20 ± 0.20) × 10^?12 for the reaction H + CH₃SH (1) and k₂ = (2.40 ± 0.16) × 10^?12 for the reaction H + C₂H₅SH (2). Units are cm³ molecule^?1 s^?1. A mass spectrometric analysis of the reaction products and a computer simulation of the reacting systems have shown that reaction (1) proceeds through two mechanisms leading to the formation of CH₃S + H₂ (1a) and CH₃ + H₂S (1b).     

Direct transfer of aliphatic and aromatic substituents from organosilatranes to mercury(II) species

The relative reaction rates of several silatranes (derivatives of 2,8.9-trioxa-5-aza- 1-silatricyclo[3.3.3.0^1,5]undecane) and HgCl₂ in acetone-d₆to yield the corresponding organomercury compound are of the order of e.g., 5 × 10^?1 1 mol^?1 sec^?1 or slightly less, a rate that is unexpectedly high compared to the essentially inert parent organotrialkoxysilanes. Thus, the apical Si&.zsbnd;C bond of the silatrane is extraordinarily susceptible to direct electrophilic attack by mercury(II). The rates decrease in the order CH₂CH, C₆H₅, p-ClC₆H₄ > CH₃ > CH₃CH₂, CH₃CH₂CH₂ > C₆H₁₁, ClCH₂, Cl₂CH, CH₃CH₂O. The effects of varying the solvent and the counterions are noted, and the probable mechanism is discussed.     

Thermodynamic functions of gaseous beryllium,titanium and germanium organometallic molecules

The thermal functions S⁰_T, -(G⁰_T-H⁰_O)/T and (H⁰_T-H⁰_O) have been calculated from structural and spectroscopic data for the gaseous organometallics C₅H₅BeX (X = Cl, Br and BH₄), C₅H₅MX₃ (M = Ti and Ge; X = Cl, Br and I) and CH₃TiX₃ (X = Cl, Br and I). The rotational barriers of the C₅H₅ and CH₃ groups have been evaluated and discussed.     

ESR Study of Nitroxide Radicals Generated from Triaz-2-en-1-ols

The triazenols 4-R¹? C₆H₄? N?N? N(OH)? R² ( 1 ), oxidized with t-BuO radicals, produced nitroxide radicals R¹? C₆H₄? N(O^?)? N?N(R²) ⁺O^? ( 5 ). The suggested radical structure was confirmed by ¹⁵N-labeling. The reaction of triazenols 1 with PbO₂ proceeded under N₂ elimination, in which case nitroxides R¹? C₆H₄? N(R₂)? O^?( 2 ) were observed as the final radical products. The intermediate R¹? C₆H radicals were identified by spin-trapping.     

Arylsulphonamides of Amidothiophosphonic Acids

Abstract

Chemical structure-antimicrobian activity correlation in a thyophosphoric arysulphonamide class were estabilished^l. The aim of this paper is to present new compounds of same type: p-substituted arylsulphonylamides of amidothiophosphonic acids, I; N-methyl and S-methyl derivatives of them, II and respectively III, synthesyzed by schemes 1 and 2(R^?=_CC₈H₁₁, C₆H₅; NR₂=N(CH₃)₂, N(C₂H₅)2, N(C₂H₄)₂O; X=F, Cl, Br, H, CH₃, OCH₃).