Protonation of γ-Butyrolactone and γ-Butyrolactam

Abstract : γ-Butyrolactone and γ-butyrolactam were reacted in the superacidic systems XF/MF₅ (X=H, D; M=As, Sb). Salts of the monoprotonated species of γ-butyrolactone were obtained in terms of [(CH₂)₃OCOH]⁺[AsF₆]⁻, [(CH₂)₃OCOH]⁺[SbF₆]⁻ and [(CH₂)₃OCOD]⁺[AsF₆]⁻ and the analogous lactam salts in terms of [(CH₂)₃NHCOH]⁺[AsF₆]⁻, [(CH₂)₃NHCOH]⁺[SbF₆]⁻ and [(CH₂)₃NDCOD]⁺[AsF₆]⁻. The salts were characterized by low temperature Raman and infrared spectroscopy and for both protonated hexafluoridoarsenates, [(CH₂)₃OCOH]⁺[AsF₆]⁻ and [(CH₂)₃NHCOH]⁺[AsF₆]⁻, single-crystal X-ray structure analyses were conducted. In addition to the experimental results, quantum chemical calculations were performed on the B3LYP/aug-cc-pVTZ level of theory. As in both crystal structures C⋅⋅⋅F contacts were observed, the nature of these contacts is discussed with Mapped Electrostatic Potential as a rate of strength.     

Unusual complex between 18-Crown-6 and tetramethylammonium cation—detection by electrospray ionization mass spectrometry

Complexes between crown ethers and quaternary ammonium cations have been studied by electrospray ionisation mass spectrometry (ESI-MS). The ESI-MS method has been shown to allow observation of not only stable inclusion complexes between large crown ethers and tetramethylammonium cation (e.g. [DB30C10 + (CH₃)₄N]⁺ ion) but also of unstable inclusion complexes between smaller crown ethers and quaternary ammonium cations which are difficult to observe by other methods, namely [18C6 + (CH₃)₄N]⁺ ion. Stability of the complexes between crown ethers containing aromatic ring and tetramethylammonium cation is enhanced by cation-Π interactions. The molecule of 18C6 does not contain aromatic rings, thus [18C6 + (CH₃)₄N]⁺ ion exists due to the formation of C–H···O hydrogen bonds. Such a complex is quite unusual, since C–H···O hydrogen bonds are very weak and usually coexist with other strong interactions.     

The preparation and reactions of group IIB metal chloride stabilized complexes of (chlorofluoromethylene)tris(dimethylamino)phosphorane

A facile dechlorination reaction occurs between [((CH₃)₂N)₃⁺PCFCl₂]Cl^? and Group IIB metals to form addition complexes of the type [((CH₃)₂N)₃P⁺ CFCl-(MCl)]Cl^? where M = Zn, Cd, or Hg. These complexes exhibit surprising stability in ethereal solvents, and serve as effective 1-chloro-1-fluorovinyl transfer agents via the Wittig reaction by dissociation into [(CH₃)₂N]₃PCFCl and the metal chloride. ¹⁹F and ³¹P NMR, as well as derivative formation, substantiate that these complexes are indeed quaternary phosphonium compounds which contain covalent carbonmetal bonds.     

The unimolecular chemistry of [1,2-propanediol]+˙: a rationale in terms of hydrogen-bridged radical cations

By combining results from a variety of mass spectrometric techniques (metastatle ion, collisional activation, collision-induced dissociative ionization, neutralization–reionization spectrometry and appearance energy measurements) and the classical method of isotopic labelling, a unified mechanism is proposed for the complex unimolecular chemistry of ionized 1,2-propanediol. The key intermediates involved are the stable hydrogen-bridged radical cations [CH₂?C(H)? H…?O…?O(H)CH₃]⁺˙, which were generated independently from [4-methoxy, 1-butanol]⁺˙ (loss of C₂H₄) and [1-methoxyglycerol]⁺˙ (loss of CH₂O), [CH₃? C?O…?H…?O(H)CH₃]⁺˙ and the related ion-dipole complex [CH₂?C(OH)CH₃/H₂O]⁺˙. The latter species serves as the precursor for the loss of CH³˙ and in this reaction the same non-ergodic behaviour is observed as in the loss of CH³˙ from the ionized enol of acetone.     

[N⋅⋅⋅I+⋅⋅⋅N] Halogen‐Bonded Dimeric Capsules from Tetrakis(3‐pyridyl)ethylene Cavitands

Two [N???I⁺???N] halogen‐bonded dimeric capsules using tetrakis(3‐pyridyl)ethylene cavitands with different lower rim alkyl chains are synthesized and analyzed in solution and the gas phase. These first examples of symmetrical dimeric capsules making use of the iodonium ion (I⁺) as the main connecting module are characterized by ¹H NMR spectroscopy, diffusion ordered NMR spectroscopy (DOSY), electrospray ionization mass spectrometry (ESI‐MS), and ion mobility‐mass spectrometry (TW‐IMS) experiments. The synthesis and effective halogen‐bonded dimerization proceeds through analogous dimeric capsules with [N???Ag⁺???N] binding motifs as the intermediates as evidenced by the X‐ray structures of (CH₂Cl₂)₂@[ 3 a ₂?Ag₄?(H₂O)₂?OTs₄] and (CH₂Cl₂)₂@[ 3 a ₂?Ag₄?(H₂O)₄?OTs₄], two structurally different capsules.     

Über die Darstellung von Dimethyl(mercapto)sulfonium-hexa-chloroantimonat [(CH3)2SSH]+SbCl6−

Preparation of Dimethyl(mercapto)sulfonium-hexachloroantimonate [(CH₃)₂SSH]⁺SbCl₆^? The preparation of [(CH₃)₂SSH]⁺SbCl₆^? from [(Ch₃)₂SCl]⁺SbCl₆^? and H₂S at 223 K is reported. This salt is stable below 243 K and is characterized by vibrational spectroscopy.     

A comparative theoretical study of the reactivities of the Al+ and Cu+ ions toward methylamine and dimethylamine

A very recent laser ablation‐molecular beam experiment shows that an Al⁺ ion can react with a single methylamine (MA, CH₃NH₂) or dimethylamine (DMA, (CH₃)₂NH) molecule to form a 1:1 ion–molecule complex Al⁺[CH₃NH₂] or Al⁺[(CH₃)₂NH)], whereas a dehydrogenated complex ion Cu⁺[CH₃N] or Cu⁺[C₂H₅N] is detected, respectively, in the similar reaction for a Cu⁺ ion. Here, we show a comparative density functional theory study for the reactivities of the Al⁺ and Cu⁺ ions toward MA and DMA to reveal the intrinsic mechanism. It is found that the interactions of the Al⁺ ion with MA and DMA are mostly electrostatic, leading to the direct ion–molecule complexes, Al⁺? NH₂CH₃ and Al⁺? NH( CH₃)₂, in contrast to the non‐negligible covalent character in the corresponding Cu⁺‐containing complexes, Cu⁺? NH₂CH₃ and Cu⁺? NH( CH₃)₂. The general dehydrogenation mechanism for MA and DMA promoted by the Cu⁺ ion has been shown, and the preponderant structures contributing to the mass spectra of the product ions Cu⁺[CH₃N] and Cu⁺[C₂H₅N] are rationalized as Cu⁺? NHCH₂ and Cu⁺? N( CH₂)( CH₃). The presumed dehydrogenation reactions are also discussed for the Al⁺‐containing systems. However, the involved barriers are found to be too high to be overcome at low energy conditions. These results have rationalized all the experimental observations well. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Synthesis,Characterization, and Crystal Structures of [N(CH3)4]2[B12H12] and [N(CH3)4]2[B12H12] · CH3CN

Bis(tetramethylammonium) dodecahydrododecaborate, [(CH₃)₄N]₂[B₁₂H₁₂], and bis(tetramethylammonium) dodecahydrododecaborate acetonitrile, [(CH₃)₄N]₂[B₁₂H₁₂] · CH₃CN, were synthesized and characterized via Infrared, ¹H and ¹¹B NMR spectroscopy. [(CH₃)₄N]₂[B₁₂H₁₂] crystallizes isopunctual to the alkali metal dodecaborates. The crystal structure of [(CH₃)₄N]₂[B₁₂H₁₂] · CH₃CN was determined from single crystal data and refined in the orthorhombic crystal system (Pcmn, no. 62, a = 898.68(8), b = 1312.85(9) c = 1994.5(1) pm, R(|F| , 4σ) = 5.9%, wR(F²) = 18.3%). Here, the geometry of the dodecaborate anion is that of an almost ideal icosahedron, less distorted than most other dodecaborates known. By low‐temperature Guinier‐Simon diffractometry phase transitions were detected for [(CH₃)₄N]₂[B₁₂H₁₂] and [(CH₃)₄N]₂[B₁₂H₁₂] · CH₃CN at –70 and –15 °C, respectively.     

3‐Rhoda‐1,2‐diazacyclopentanes: A Series of Novel Metallacycle Complexes Derived From CN Functionalization of Ethylene

Rh‐containing metallacycles, [(TPA)Rh^III(κ²‐(C,N)‐CH₂CH₂(NR)₂‐]Cl; TPA=N,N,N,N‐tris(2‐pyridylmethyl)amine have been accessed through treatment of the Rh^I ethylene complex, [(TPA)Rh(η²‐CH₂CH₂)]Cl ([ 1 ]Cl) with substituted diazenes. We show this methodology to be tolerant of electron‐deficient azo compounds including azo diesters (RCO₂N?NCO₂R; R=Et [ 3 ]Cl, R=iPr [ 4 ]Cl, R=tBu [ 5 ]Cl, and R=Bn [ 6 ]Cl) and a cyclic azo diamide: 4‐phenyl‐1,2,4‐triazole‐3,5‐dione (PTAD), [ 7 ]Cl. The latter complex features two ortho‐fused ring systems and constitutes the first 3‐rhoda‐1,2‐diazabicyclo[3.3.0]octane. Preliminary evidence suggests that these complexes result from N–N coordination followed by insertion of ethylene into a [Rh]?N bond. In terms of reactivity, [ 3 ]Cl and [ 4 ]Cl successfully undergo ring‐opening using p‐toluenesulfonic acid, affording the Rh chlorides, [(TPA)Rh^III(Cl)(κ¹‐(C)‐CH₂CH₂(NCO₂R)(NHCO₂R)]OTs; [ 13 ]OTs and [ 14 ]OTs. Deprotection of [ 5 ]Cl using trifluoroacetic acid was also found to give an ethyl substituted, end‐on coordinated diazene [(TPA)Rh^III(κ²‐(C,N)‐CH₂CH₂(NH)₂‐]⁺ [ 16 ]Cl, a hitherto unreported motif. Treatment of [ 16 ]Cl with acetyl chloride resulted in the bisacetylated adduct [(TPA)Rh^III(κ²‐(C,N)‐CH₂CH₂(NAc)₂‐]⁺, [ 17 ]Cl. Treatment of [ 1 ]Cl with AcN?NAc did not give the Rh?N insertion product, but instead the N,O‐chelated complex [(TPA)Rh^I ( κ²‐(O,N)‐CH₃(CO)(NH)(N?C(CH₃)(OCH?CH₂))]Cl [ 23 ]Cl, presumably through insertion of ethylene into a [Rh]?O bond.     

Die Reaktion von Tellurhexafluorid mit Trimethylamin,Strukturen der TeF5−- und SeF5−-Anionen

Reaction of Telluriumhexafluoride and Trimethylamine, Structures of the TeF₅^? and SeF₅^? Anions The reaction of TeF₆ and (CH₃)₃N is of the redox kind, resulting in reduction of tellurium: X-ray single crystal analysis reveals the compounds (CH₃)₂N? CH₂? N(CH₃)₂⁺TeF₅^? and [(CH₃)₃NH⁺]₅(TeF₅^?)₃(HF₂^?)₂. By comparison with published data it can be shown that this mixture is identical to previously published [(CH₃)₃N]₂TeF₆. The latter was supposed to be one of the few examples of tellurium in a coordination state of eight. (CH₃)₄N⁺TeF₅^? and (CH₃)₄N⁴SeF₅^? are obtained and their structure is investigated by single crystal x-ray methods also. The anions SF₅^?, SeF₅^? and TeF₅^? are discussed in terms of weak interactions.     

Synthesis and Physicochemical Characteristics of New Tetrachloroferrates(III) with Dimethylammonium Cation: X‐ray Crystal Structure of Bis(dimethylammonium) Chloride Tetrachloroferrate(III)

Two new tetrachloroferrates(III) have been synthesized of molecular formulas [(CH₃)₂NH₂][FeCl₄] and [(CH₃)₂NH₂]₂FeCl₅. The differences in their physicochemical properties have been highlighted using thermal analysis (TG‐MS) and differential scanning calorimetry (DSC). The crystal and molecular structure of [(CH₃)₂NH]₂FeCl₅ was determined. The iron(III) cation is four coordinated by chloride ions, and it adopts a slightly distorted tetrahedral coordination with three angles smaller and three larger than the tetrahedral one. In the structure four intermolecular N‐H···Cl hydrogen bonds link the [(CH₃)₂NH₂]⁺ cations to dimers via a Cl^? bridge.     

Gas-phase ion–molecule reactions in dilute mixtures of dimethyl ether in krypton. Bimolecular and clustering reactions

The results of high-pressure variable-temperature and variable ionizing electron energy studies of gas-phase ion-molecule reactions of dimethyl ether in krypton are presented. Near the ionization threshold a series of peaks corresponding to (CH₃OCH₃)_nH⁺ (n = 1-4) clusters are observed. At higher ionizing electron energies, two new series of peaks appear, corresponding to [CH₃OCH₂]⁺(CH₃OCH₃)_n and [(CH₃)₃O]⁺ (CH₃OCH₃)_n clusters. The onium ion, [(CH₃)₃O]⁺, has been previously reported at elevated temperatures under methane chemical ionization conditions. It was suggested that the onium ion is formed by reaction of (CH₃)₂OH⁺ with CH₃OCH₃ with subsequent elimination of methanel, i.e. by fragmentation of an adduct ion. The present results strongly suggest that, under our conditions, [CH₃OCH₂]⁺ rather than thermal (CH₃)₃OH⁺, is the precursor to [(CH₃)₃O]⁺.     

Intermolecular methyl transfer on pyrolysis of carpronium chloride

The methyl transfer occurring in the production of methyl N,N-dimethyl-γ-aminobutyrate by pyrolysis of carpronium chloride was examined by means of pyrolysis gas chromatography mass spectrometry with the aid of some deuterated compounds. The mass spectra of methyl N,N-dimethyl-γ-aminobutyrate, produced from deuterated derivatives of carpronium chloride, showed inter alia, characteristic molecular ion peaks which indicated that the methyl of the trimethylammonium group transfers and displaces the methyl of the carbomethoxy group of the tertiary amino compound. The results show that an intermolecular methyl transfer occurs in part on pyrolysis of carpronium chloride, to form methyl N,N-dimethyl-γ-aminobutyrate in which the methyl oxygen is replaced by a methyl from the nitrogen of the original compound. The mechanism presented involves the bimolecular reaction between zwitterionic intermediates formed by ionic O-demethylation of carpronium chloride.     

Electron paramagnetic resonance of γ-irradiated [(CH3)4N]2ZnF4 and [(CH3)4N]2CdF4 single crystals and vibrational spectra of their unirradiated forms

γ-Irradiated [(CH₃)₄N]₂ZnF₄ and [(CH₃)₄N]₂CdF₄ single crystals were investigated by electron paramagnetic resonance (EPR) and vibrational spectroscopy of their unirradiated forms at ambient temperature. It has been found that both compounds indicate the existence of (CH₃)₃ N˙⁺ radicals. The g factors were found to be isotropic and the hyperfine constant for protons of the methyl groups was measured as 28.9 G for this radical in these substances. Each methyl group rotates around its C_3ν-axis and also rotates around the C_3ν-axis of the (CH₃)₃ N˙⁺ radical. In addition to these motions, the C_3ν-axis of the (CH₃)₃ N˙⁺ radical seems to rotate around the z-axis. These results were compared with the earlier studies in (CH₃)₃ N˙⁺ radical and discussed. The vibrational spectra of these two compounds were discussed in relation to other compounds containing tetramethylammonium salts. The assignments of the observed bands were discussed.     

Fragmentation of acylium ions from methyl levulinate. Isomerization processes involving carbon and oxygen atoms of both carbonyl groups

The fragmentations of the acylium ions O?C⁺? CH₂? CH₂? CO₂CH₃ and O?C⁺? CH₂? CH₂? COCH₃ generated from methyl levulinate are governed extensively by the interaction of the two carbonyl groups. Both species eliminate a molecule of CO unimolecularly and under CID conditions. The results derived from measurements of ¹³C and ¹⁸O labelled precursors, together with kinetic energy release values, have been used to study the mechanisms. In the first of these acylium ions, both carbonyl groups are equivalent; this phenomenon can be the result of a 1,4 methoxy shift. In the second acylium ion, only the oxygen atoms change their positions; this isomerization occurs via the [M? H]⁺ of γ-valerolactone. Some other fragmentation processes also discussed in relation to ²H labelling are the formation of the [M ? COOCH₃] ⁺ ion and the loss of HCOOCH₃ in the collision-induced dissociation mass spectra of the first acylium ion, and the formation of the [CH₃CO]⁺ ion and the loss of H₂O for the second one.     

Addukte aus Phosphorylverbindungen und SbCl5 Darstellung und IR-Spektren der 1:1-Addukte aus Chlordimethylamino- bzw. Chlordimethylamino-methoxi-phosphorylverbindungen und Antimon(V)-chlorid

Adducts of Phosphoryl Compounds and SbCl₅ Preparation and IR Spectra of 1:1 Addition Compounds from Chlorodimethylamino- resp. Chlorodimethylaminomethoxiphosphoryl Compounds and Antimony(V) Chloride The addition compounds (CH₃O)₂[(CH₃)₂N]PO · SbCl₅ ( II ), (CH₃O)[(CH₃)₂N]₂PO · SbCl₅ ( III ), [(CH₃)₂N]₃PO · SbCl₅ ( IV ), Cl₂[(CH₃)₂N]PO · SbCl₅ ( VI ), Cl[(CH₃)₂N]₂PO · SbCl₅ ( VII ), and Cl(CH₃O)[(CH₃)₂N]PO · SbCl₅ ( VIII ) are prepared by reaction of the phosphoryl compounds with antimony(V) chloride. The influence of the Lewis acid to the bonds of the phosphoryl compounds is discussed. The ³¹P-n.m.r. data of the adducts are communicated and compared with those of the free phosphoryl compounds.     

Behavior of octa(benzo-15-crown-5)- and tetrasulfophthalocyanines in the presence of water-soluble C60 compounds

Octa[(4′-benzo-15-crown-5)oxy]phthalocyanine was shown to dissolve in the presence of water-soluble fullerene compounds C₆₀Cl(NHCH₂CH₂NH₃ ⁺)₅(^?OOCCF₃)₅ or C₆₀Cl(C₆H₄CH₂CH₂COONa)₅. The solubilization of phthalocyanine was attributed to the possibility of formation of the hydrogen bonds N-H...O(CH₂) and coordination of the sodium cations inside the cavities of the crown ether fragments for the cationic and anionic fullerene derivatives, respectively. Solubilization of the crown-containing phthalocyanine with participation of water-soluble fullerene compounds proceeded with the formation of aggregated forms. A monomeric form of nickel tetrasulfonated phthalocyaninate in the presence of an equimolar amount of C₆₀Cl(NHCH₂CH₂NH₃ ⁺)₅(^?OOCCF₃)₅ in 50% ethanol is transformed into a dimeric form. The structures of the fullerene-containing compounds and their state in solution facilitate the stacking aggregation of phthalocyanines.     

Synthese,Aufbau und Eigenschaften Käfigartiger vinyl- und allylsilylierter Kieselsäuren

Synthesis, Constitution and Properties of Cage-like Vinyl- and Allylsilylated Silicic Acids By silyation of tetramethylammonium silicate [N(CH₃)₄]₈Si₈O₂₀ · 69 H₂O with vinyldimethylchlorosilane ( I ) and divinyltetramethyldisiloxane, respectively, or allyldimethylchlorosilane there were synthesized the crystalline silicic esters [CH₂?CH(CH₃)₂Si]₈Si₈O₂₀ and[CH₂?CH? CH₂(CH₃)₂Si]₈Si₈O₂₀. By means of gas chromatography, mass spectrometry, ¹H and ²⁹Si NMR the two compounds were identified to be cage-like double four-ring(D4R)-silicic esters containing eight vinyldimethylsilyl- or allyldimethylsilyl groups, Silylation with a mixture of I and trimethylchlorosilane yields in dependence on the ratio of silanes vinyldimethylsilyltrimethylsilyl D4R silicic esters with average numbers of unsaturated groups < 8.     

Characterization of five [C4H7O]+ Ion structures. Fragmentation of the 2-pentanone molecular ion

The [C₄H₇0]⁺ ions [CH₂?CH? C(?OH)CH₃]⁺ (1), [CH₃CH?CH? C(?OH)H]⁺ (2), [CH₂?C(CH₃)C(?OH)H]⁺ (3), [Ch₃CH₂CH₂C?O]⁺ (4) and [(CH₃)₂CHC?O]⁺ (5) have been characterized by their collision-induced dissociation (CID) mass spectra and charge stripping mass spectra. The ions 1–3 were prepared by gas phase protonation of the relevant carbonyl compounds while 4 and 5 were prepared by dissociative electron impact ionization of the appropriate carbonyl compounds. Only 2 and 3 give similar spectra and are difficult to distinguish from each other; the remaining ions can be readily characterized by either their CID mass spectra or their charge stripping mass spectra. The 2-pentanone molecular ion fragments by loss of the C(1) methyl and the C(5) methyl in the ratio 60:40 for metastable ions; at higher internal energies loss of the C(1) methyl becomes more favoured. Metastable ion characteristics, CID mass spectra and charge stripping mass spectra all show that loss of the C(1) methyl leads to formation of the acyl ion 4, while loss of the C(5) methyl leads to formation of protonated vinyl methyl ketone (1). These results are in agreement with the previously proposed potential energy diagram for the [C₅H₁₀O]⁺˙ system.     

Die Konstitution des Tetramethylammoniumsilicats der Zusammensetzung 1,0 N(CH3)4OH 1,0 SiO2 · 8,0–8,3 H2O

By means of paperchromatographic, kinetic and X-ray methods it is shown that the tetramethylammonium silicate of the composition 1 N(CH₃)₄OH · 1 SiO₂ · ～8 H₂O has not – as hitherto supposed – the constitution of a poly- or phyllosilicate, but that of a tetra-anhydrido-bis-cyclotetrasilicate (double-fourringsilicate), [(CH₃)₄N]₈[Si₈O₂₀] · ～69 H₂O. Its trimethylsilylation by means of hexamethyldisiloxane gives the corresponding, crystalline trimethylsilyl ester [(CH₃)₃Si]₈[Si₈O₂₀], which has been characterised by mass spectroscopy.