Gas-phase reactions of free phenylium cations with C3H6 hydrocarbons

Free, unsolvated phenylium ions formed by the spontaneous β decay of a constituent atom of multitritiated benzene have been allowed to react with gaseous propene and cyclopropane in the pressure range from 10 to 700 torr. Phenylium ions attack efficiently both the C-H and the C-C bonds of cyclopropane, yielding respectively tritiated cyclopropylbenzene and indane as the major products. Selective attack of phenylium ions on the π bond of propene is suggested by the composition of tritiated products, isomeric phenylpropenes and isopropylbenzene. The different behavior of propene and cyclopropane toward gaseous phenylium ions is consistent with the results of related radiolytic investigations concerning gaseous systems at nearly atmospheric pressure. The reactivity pattern of the isomeric C₃H₆ hydrocarbons toward gaseous phenylium ions is discussed and compared with pertinent mass spectrometric data.     

Site Selectivity in the Gas-Phase Ionic Phenylation of Alcohols and Alkyl Chlorides

Free, unsolvated phenylium ions formed by the spontaneous β decay of [1,4-³H₂]benzene have been allowed to react with gaseous alcohols (ROH: R = Et, CF₃CH₂, Pr, or i-Pr; partial pressure: 3–56 Torr) and alkyl chlorides (R′Cl: R′ = Pr, i-Pr, or Bu; partial pressure: 20–450 Torr), in the presence of a thermal radical scavenger (O₂: 4 Torr). Phenylium ion confirms its considerable site selectivity, demonstrated by the distinct preference toward the n-centre of the substrate (46–100%), although significant insertion into the alkyl group of alcohols is observed as well. Phenylium ion displays significant positional selectivity even between different n-type sites in a bidentate molecule such as CF₃CH₂OH. An affinity F < O < Cl trend is observed, which indicates a direct relationship between the polarizability of the n-centre of the molecule and its orienting properties toward phenylium ion. The stability features of the ionic intermediates from addition of phenylium ion with ROH or R′Cl have been evaluated, as well as their fragmentation and isomerization mechanisms. The behaviour of phenylium ion toward the selected substrates in the gas phase is discussed and compared with previous mechanistic hypotheses from related nuclear-decay studies.     

Formation of organometallic compounds of carbene and carbine types by the interaction of RLi with neodymium and yttrium chlorides in various media

It has been established that in the interaction of NdCl₃ and YCl₃ with RLi, where R  CH₂C₆H₅, CH₂C(CH₃)₂C₆H₅, CH₂Si(CH₃)₃, unusual organometallic compounds are formed. They are stable in hydrocarbon solutions. The benzyl and neophyl derivatives are carbene type complexes containing one R group at a trivalent metal atom. In all cases the reaction is accompanied by the evolution of RH as the main product and some stilbene and tolan when R  CH₂C₆H₅. The mechanism of this reaction is discussed.     

Gas-phase phenylium and acyclic [C6H5]+ isomers

The structures of [C₆H₅]⁺ species, formed from a variety of precursors, have been investigated by ion/molecule reactivity studies with pulsed ion cyclotron resonance mass spectrometry and by collision spectroscopy with mass-analyzed ion kinetic energy spectrometry. Formed by sequential ion/molecule reactions in gaseous acetylene, the [C₆H₅]⁺ species are present as a mixture of isomers, those that react with acetylene and those that do not. Ion-assisted dehalogenation reactions were used to establish that the unreactive [C₆H₅]⁺ isomer was the phenylium ion. These data were used to study and confirm collisional decomposition reactions postulated to be diagnostic of the acyclic and phenylium isomers. These diagnostic reactions were then used to study the composition of the [C₆H₅]⁺ isomers produced by electron ionization of a number of precursors. These results are contrasted with previous studies and the collision spectroscopy experiments are described in detail. The possible role of [C₆H₅]⁺ species in flame processes is discussed.     

Mass spectrometry of transition metal π-complexes. XV—The effect of substituents on the fragmentation of benchrotrenyls under electron impact

Mass spectra of substituted benchrotrenyls RC₆H₅Cr(CO)₃ where R?H, F, CI, I, CH₃, OCH₃, COOCH₃, C₂H₅, N(CH₃)₂, NH₂, C₆H₅, C(CH₃)₃, p-C₆H₄NH₂, CH₂C₆H₅, CH₂CH₂C₆H₅), 1,3,5-(CH₃)₃C₆H₃Cr(CO)₃ and 1,2,3,5-(CH₃)₄C₆H₂Cr(CO)₃ have been studied. It has been found that for monosubstituted benchrotrenyls there is a linear dependence of the parameter log [Cr]⁺/[RC₆H₅Cr]⁺) on the number of degrees of freedom of the [RC₆H₅Cr]⁺ ion. Decarbonylation of the molecular ions is not affected by the nature of the substituent R. The results are interpreted in terms of the quasi-equilibrium theory of mass spectra.     

Optisch aktive übergangsmetall-komplexe LXIV. Neue optisch aktive Cp(CO)Fe-acyl-komplexe mit

The novel complexes CpFe(CO)(COR)P(C₆H₅)₂NR'R^* with Cp = C₅H₅,C₉H₇ (indenyl); R = CH₃, C₂H₅, CH(CH₃)₂, CH₂C₆H₅;R` = H, CH<sub>3</sub>, C<sub>2</sub>H<sub>5</sub>, CH<sub>2</sub>C<sub>6</sub>H<sub>5</sub> and R<sup>*</sup> = (S)-CH(CH<sub>3</sub>)(C<sub>6</sub>H<sub>5</sub>), have been synthesized by reaction of CpFe(CO)<sub>2</sub>R wiht P(C<sub>6</sub>H<sub>5</sub>)<sub>2</sub>NR`R^* and characterized analytically as well as spectroscopically. The pairs of diastereoisomers RS/SS have been separated by preparative liquid chromatography and fractional crystallization, respectively. The optically pure complexes (+)₄₃₆- und ()₄₃₆-CpFe(CO)(COR)P(C₆H₅)₂NR`R^* are configurationally stable at room temperature. At higher temperatures they equilibrate with CpFe(CO)₂R and epimerize with respect to the Fe configuration.     

Silicium-stickstoff-fluorverbidungen: V. Darstellung neuer silylaminofluorsilane

Compounds of the composition RR′SiFNR″Si(CH₃)₃ (R = H, F, CH₃, C₂H₅, C₃H₇, C₂H₃, C₆H₅, C(CH₃)₃; R = F, CH₃, C₆H₅; R″ = CH₃, C(CH₃)₃, Si(CH₃)₃) are obtained by the reaction of silicontetrafluoride or organo-substituted silicon-fluorides with the lithium salts of alkylsilylamines in a molar ratio of $\text{1}\text{1}$. The disubstituted compounds RSiF(NR′Si(CH₃)₃)₂ (R = H, F, CH₃, C₂H₃, C₆H₅; R′ = CH₃, C(CH₃)₃) result when the reactants are in a $\text{1}\text{2}$ molar-ratio. Likewise the unsymmetrical siliconfluorsilylamines of the formulae F₂Si(NRSi(CH₃)₃) (NR′Si(CH₃)₃) (R = CH₃, R′ = C(CH₃)₃), as well as the trisubstituted compounds FSi(NCH₃Si(CH₃)₃)₃ and FSi(NCH₃Si(CH₃)₃)₂(N(Si(CH₃)₃)₂) were made. By reacting phenyltrifluorsilane with dialkylamines ($\text{1}\text{2}$) C₆H₅SiF₂NR₂(R = CH₃, C₂H₅) was obtained. The IR-, mass-, ¹H and ¹⁹F NMR spectra of the above-mentioned compounds are reported.     

Laser induced time-dependent thermal lensing studies of vibrational relaxation: translational cooling in CH3F

Time-resolved measurements of the thermal lens effect have been made for CH₃F, CH₃CI and C₂H₄. This technique is compared to others used in the study of vibrational relaxation phenomena and is found to be applicable to the study of a wide variety of gaseous systems at relatively low pressures. Translational cooling has been observed in CH₃F and an approximate lower limit of 200 msec^-1 has been established for the rate of this cooling process, which corresponds to equilibration of the ν₃ and ν₆ states, in a mixture of 0.2 torr CH₃F and 10 torr Ar.     

Synthese und Charakterisierung donor-funktionalisierter ansa-Metallocene von Yttrium,Neodym, Samarium,Erbium und Lutetium

Organometallic Compounds of the Lanthanides. 133 Synthesis and Characterization of donor-functionalised ansa -Metallocenes of Yttrium, Neodymium, Samarium, Erbium, and Lutetium The reaction of Me₂SiCl₂ with K[C₅H₄^tBu], Li[C₅H₄SiMe₃] or K[C₅H₃^tBuMe-3] followed by treatment with K[C₅H₄CH₂CH₂NMe₂] yields mixed substituted dicyclopentadienyldimethylsilanes which after double deprotonation with KH afford the dipotassium salts K₂[Me₂Si(C₅H₃^tBu-3)(C₅H₃CH₂CH₂NMe₂-3)] ( 1 ), K₂[Me₂Si · (C₅H₃SiMe₃-3)(C₅H₃CH₂CH₂NMe₂-3)] ( 2 ), and K₂[Me₂Si · (C₅H₂^tBu-3-Me-5)(C₅H₃CH₂CH₂NMe₂-3)] ( 3 ), respectively. The reaction of 1 , 2 , or 3 with LnCl₃(THF)_x (Ln = Y, La, Nd, Sm, Er, Lu) leads to the complexes [Me₂Si(C₅H₃^tBu-3) · (C₅H₃CH₂CH₂NMe₂-3)]LnCl [Ln = Y ( 4 a ), Sm ( 4 c ), Lu ( 4 e )], [Me₂Si(C₅H₃SiMe₃-3)(C₅H₃CH₂CH₂NMe₂-3)]LnCl [Ln = Y ( 5 a ), Sm ( 5 c ), Lu ( 5 e )], and [Me₂Si(C₅H₂^tBu-3-Me-5)(C₅H₃CH₂CH₂NMe₂-3)]LnCl [Ln = Y ( 6 a ), Nd ( 6 b ), Sm ( 6 c ), Er ( 6 d ), Lu ( 6 e )], respectively. Alkylation of 4 a , 4 c , 5 a , and 6 b , 6 e with LiCH₃, LiCH₂SiMe₃, and LiCH(SiMe₃)₂ produces the alkylmetallocenes [Me₂Si(C₅H₃^tBu-3) · (C₅H₃CH₂CH₂NMe₂-3)]LnR [R = CH₃, Ln = Y ( 7 a ), Sm ( 7 c ); R = CH₂SiMe₃, Ln = Y ( 8 a )], [Me₂Si(C₅H₃SiMe₃-3) · (C₅H₃CH₂CH₂NMe₂-3)]YCH₃ ( 9 a ), and [Me₂Si(C₅H₂^tBu3-Me-5)(C₅H₃CH₂CH₂NMe₂-3)]LnR (R = CH₃, Ln = Lu ( 10 e ); R = CH₂SiMe₃, Ln = Lu ( 11 e ); R = CH(SiMe₃)₂, Ln = Nd ( 12 b ), Lu ( 12 e )], respectively. All new compounds were characterized by elemental analyses, NMR spectroscopy and mass spectrometry. The molecular structure of 6 c and 6 e was determined by single crystal X-ray structure analysis.     

Studies on organophosphorus compounds XLVIII Synthesis of Dithioesters from P,S-Containing Reagents and Carboxylic Acids and Their Derivatives

2,4-Bismethylthio-1,3,2,4-dithiadiphosphetane 2,4- disulfide, IIa, is prepared from 0,0-dimethyldithiophosphoric acid, Ia, and P₄S₁₀ at 160°C. 2,4-Bis(4-phenoxyphenyl)-1,3,2,4- dithiadiphsophetane 2,4-disulfide, IIc, and 2,4-bis(4-phenylthiolophenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, IId, are prepared at l60°C from P₄ S₁₀ and diphenylether and diphenylsulfides, respectively. Carboxylic acids RCOOH(R = CH₃ C₂H₅, n-C₃H₇, n-C₄H₉, C₆H₅CH₂, C₆H₈) react with compound Ia at 130°C to give the corresponding methyl dithioesters. Carboxylic acids RCOOH (R = C₆H₈-CH₂, C₆H₈) react with compound Ib at 200°C for 15 min to give the corresponding ethyl dithioesters, while low boiling acids (R = CH₃, C₂H₈, n-C₃H₇) yielded mixtures of the corresponding ethyl dithioester and ethyl carboxylate. Carboxylic acid chlorides RCOCl (R = ClCH₂, C₂H₅, t-C₄H₅ C₆H₅CH₂, C₆H₅, P-NO₂C₆H₄) react with compound IIa at 80°C to give the corresponding methyl dithioesters in good yields. S-Substituted thioesters react with IIC at 85°C to give the corresponding dithioesters in good yields. Dihydro2(3H)-furanone, VI, and 5-methyl-2(3H)-furanone, VII, react with IIa at 80°C; to dihydro-2(3H)-thiophenethione, VIII and 2,2'-dithiobis(5-methyl thiophene),IX, respectively. Also XI reacts with IIa,IIc, and IId to give VIII in nearly quantitative yields.     

Selected rate constants for H,O, N,and Cl atoms with substrates at room temperatures

Rate constants for H + Cl₂, H + CH₃CHO, H + C₃H₄, O + C₃H₆, O + CH₃CHO, and Cl + CH₄ have been measured at room temperature by the discharge flow—resonance fluorescence technique. The results are (1.6 ± 0.1) × 10^?11, (9.8 ± 0.8) × 10 ^?14, (6.3 ± 0.4) × 10^{?13) (2.00 torr He), (3.95 ± 0.41) × 10?12, (4.9 ± 0.5) × 10|su?13} and (1.08 ± 0.07) × 10^?13, respectively, all in units of cm³ molecule^?1 s^?1. Also N atom reactions with C₂H₂, C₂H₄, C₃H₄, and C₃H₆ were studied but in no case was there an appreciable rate constant. These results are compared to previous studies.     

Reactions of (η5-C5H5)2Tir compounds with organic cyanides

The syntheses and properties of the titanium(III) complexes Cp₂Tir · R′CN (R = C₆H₅, o-, m-, p-CH₃C₆H₄, CH₂C₆H₅, C₆F₅, Cl; R′ = CH₃, t-C₄H₉, C₆H₅, o-CH₃C₆H₄, 2,6-(CH₃)₂C₆H₃) are described. In the complexes the nitrogen atom of the cyanide ligands is coordinated to the metal. The thermal stabilities of the complexes depend markedly on R and R′; on heating they undergo a novel reaction in which two cyanide ligands are coupled by formation of a CC bond, while the metal is oxidized to titanium(IV).     

Polymerization of cyclic esters of phosphoric acid. VI. Poly(alkyl ethylene phosphates). Polymerization of 2-alkoxy-2-oxo-1,3,2-dioxaphospholans and structure of polymers

Five-membered cyclic esters of phosphoric acid of the general formula: ? CH₂CH(R)OP(O)-(OR′)O? polymerize readily to solid, soluble polymers of high molecular weight without any rearrangement known for various tri- and pentavalent organophosphorus monomers. ¹H-, ¹³C-, and ³¹P-NMR spectra of polymers confirmed their linear structure: where R is H, with R′ = CH₃, C₂H₅, n-C₃H₇, i-C₃H₇; n-C₄H₉, CCl₃CH₂, or C₆H₅, or R is CH₂Cl and R′ is C₂H₅. The use of n-C₄H₉Li, (C₅H₅)₂Mg, or (i-C₄H₉)₃Al as initiators leads to polymers with M _n = 10⁴–10⁵.     

Die Elektronenstoßfragmentierung von substituierten Dimethylalkoxysilanen

Electron Impact Fragmentation of Substituted Dimethylalkoxysilanes The mass spectra of substitued dimethylalkoxysilanes (H₃C)₂SiOCH₃R (R ? ? F, ? Cl, ? H, ? OCH₃, ? C₆H₅, ? CH₃, ? C₂H₅, ? n-C₃H₇), and (H₃C)₂SiOC₂H₅R (R ? ? Cl, ? C₆H₅, ? CH₃, ? C₂H₅) have been recorded and the fragmentation patterns are presented. The yield of the electron impact induced reaction (M-15)⁺→(M-45)⁺+ H₂CO occuring upon fragmentation of substituted dimethylmethoxysilanes depends on the substituent R. A quantum chemical calculation was carried out by CNDO/2 method to determine the electron density distribution in the ion at mass number (M-15). It is shown that a correlation exists between the Si? O? π bond order in this ion and the yield as well as the activation energy of this reaction.     

Novel heterocyclic selenazadiphospholaminediselenides, zwitterionic carbamidoyl(phenyl)-phosphinodiselenoic acids and selenoureas derived from cyanamides

2,4-Bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide (Woollins’ reagent, WR) reacts with cyanamides (1a-h) in refluxing toluene to afford a series of novel selenazadiphospholaminediselenides (RR′NCN(PhP(Se)SeP(Se)Ph, R=C₆H₅(CH₂)_1-3, 4-n-C₁₀H₂₁C₆H₄ and 4-BrC₆H₄CH₂; R′=H, CH₃, C₂H₅ and C(O)OC₂H₅2a-g). Post-treatment of the reaction mixture with water led to the formation of carbamidoyl(phenyl)phosphinodiselenoic acids (RR′NC(NH₂)P(SeH)₂Ph, R=C₆H₅(CH₂)_2-3, 4-n-C₁₀H₂₁C₆H₄ and 4-BrC₆H₄CH₂; R′=H and CH₃, 3b, 3c, 3e and 3f) and selenoureas (RR′NC(Se)NH₂, R=C₆H₅(CH)_1-2; R′=CH₃ and OC(O)C₂H₅, 4f and 4h) in moderate to excellent yields. All new compounds are characterised spectroscopically and five X-ray crystal structures are reported.     

Amidrazones. VII. Formation of s-triazines by thermolysis of N1-benzyl-substituted amidrazone ylides

The preparation of ylides of the general structure is described. Thermolysis of 14a (R = CH₃, R' = H, Ar = C₆H₅) gave dimethylamine and 2,4-dimethyl-6-phenyl-s-triazine. Thermolysis of ylides 14b (R = C₆H₅; R' = CH₃, Ar = C₆H₅) and 14c (R = C₆H₅, R' = CH₃, Ar = p-tolyl) gave dimethylamine, ArCH = NCH₃ and 1-methyl-2-Ar-4,6-diphenyl-1,2-dihydro-s-triazines ( 19a,b ). Triazines 19a and 19b were also prepared by condensation of N-methylbenzamidine with benzaldehyde and p-tolualdehyde, respectively. Thermolysis of 14d (R = C₆H₅, R¹ = CH₂C₆H₅,Ar = C₆H₅) gave 1-benzyl-2,4,6-triphenyl-1,2-dihydro-s-triazine ( 19c ) and N-benzylidenebenzylamine. Mechanistic aspects of these reactions are discussed.     

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.     

Some novel triorganotin(IV) derivatives of β, δ-triketones

Thirty triorganotin(IV) derivatives of the type R₃Sn(R′COCHCOCH₂COR″) and [R₃Sn]₂ (R′COCHCOCHCOR″) (where R = CH₃, C₂H₅, nC₃H₇, nC₄H₉ and C₆H₅ and R′ = R″ = CH₃, C₆H₅ or R′ = C₆H₅, R″ = CH₃) have been synthesised by the interaction of R₃SnCl with mono- or disodium salt of 2, 4, 6-heptanetrione, 1-phenyl-1, 3, 5-hexanetrione and 1, 5-diphenyl-1, 3, 5-pentanetrione in 1:1 and 2:1 molar ratios, respectively. The complexes have been examined by their molecular weight, IR, PMR and elemental analyses and their tentative structures assigned. Both “Z” and “E” forms have been identified in the 1:1 complexes in equilibrium with the enol form containing five coordinate tin. The 2:1 derivatives contain one five- and other four coordinated tin(IV) except the phenyl analogue where both the tins are five coordinated.     

Reactions of the copper dimer,Cu2, in the gas phase

Reactions of Cu₂ with several small molecules have been studied in the gas phase, under thermalized conditions at room temperature, in a fast-flow reactor. They fall into one of two categories. Cu₂ does not react with O₂, N₂O, N₂, H₂, and CH₄ at pressures up to 6 torr. This implies bimolecular rate constants of less than 5 × 10^?15 cm³ s^?1 at 6 torr He. Cu₂ reacts with CO, NH₃, C₂H₄, and C₃H₆ in a manner characteristic of association reactions. Second-order rate constants for all four of these reagents are dependent on total pressure. The reactions with CO, NH₃, and C₂H₄ are in their low pressure limit at up to 6 torr He buffer gas pressure. The reaction with C₃H₆ begins to show fall-off behavior at pressures above 3 torr. Limiting low-pressure, third-order rate constants are 0.66 ± 0.10, 8.8 ± 1.2, 9.3 ± 1.4, and 85 ± 15 × 10^?30 cm⁶ s^?1 in He for CO, NH₃, C₂H₄, and C₃H₆, respectively. Modeling studies of these rate constants imply that the association complexes are bound by at least 20 kcal mol^?1 in the case of C₂H₄ and C₃H₆ and at least 25 kcal mol^?1 in the other cases. The implications of these results for Cu-ligand bonding are developed in comparison with existing work on the interactions of these ligands with Cu atoms, larger clusters, and surfaces. © 1994 John Wiley & Sons, Inc.     

Über Chalkogenolate. LVII. Untersuchungen über Thioameisensäuren 5. Darstellung und Eigenschaften von Estern der Dithioameisensäure

Esters of the trimeric dithioformic acid [HCS(SR)]₃ were prepared by interaction of K[HCS₂] with alkyl iodides (R = CH₃, C₂H₅). Orthoesters HC(SR)₃ and di-orthoesters of the monomeric dithioformic acid were formed by reaction of formic acid with thioles (RSH mit R = CH₃, C₂H₅, CH₂C₆H₅) or dithioles (HS? (CH₂)_n? SH with n = 2, 3,4). The prepared compound were characterised by different methods.