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1.
Wei‐Cheng Xiong Guang‐Ao Yu Quan Gan Jun Yin Xiang‐Gao Meng Sheng Hua Liu 《应用有机金属化学》2007,21(9):794-797
Formal [2 + 2 + 2] addition reactions of [Cp*Ru(H2O)(NBD)]BF4 (NBD = norbornadiene) with PhC?CR (R = H, COOEt) give [Cp*Ru(η6‐C6H5? C9H8R)] BF4 (1a, R = H; 2a, R = COOEt). Treatment of [Cp*Ru(H2O)(NBD)]BF4 with PhC?C? C?CPh does not give [2 + 2 + 2] addition product, but [Cp*Ru(η6‐C6H5? C?C? C?CPh)] BF4(3a). Treatment of 1a, 2a, 3a with NaBPh4 affords [Cp*Ru(η6‐C6H5? C9H8R)] BPh4 (1b, R = H; 2b, R = COOEt) and [Cp*Ru(η6‐C6H5? C?C? C?CPh)] BPh4(3b). The structures of 1b, 2b and 3b were determined by X‐ray crystallography. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
2.
Acyl- and Alkylidenephosphines. XXIV. (N,N-Dimethylthiocarbamoyl)trimethylsilyl-phosphines and 1.2-Di(tert-butyl)-3-dimethylamino-1-thio-4-trimethylsilylsulfano-1λ5, 2λ3-diphosphet-3-ene In contrast to bis(trimethylsilyl)phosphines R? P[? Si(CH3)3]2 1 {R ? H3C a ; (H3C)3C b ; H5H6 c ; H11C9 d ; (H3C)3Si e }, the more nucleophilic lithium trimethylsilylphosphides 4 react with N,N-dimethylthiocarbamoyl chloride already at ?78°C to give (N,N-dimethylthiocarbamoyl)trimethylsilylphosphines 2 . Working up the reaction, a dismutation of the mesityl derivative 2d is observed, whereas the tert-butyl compound 2b dissolved in toluene, eliminates dimethyl(trimethylsilyl)amine to form 1,2-di(tert-butyl)-3-dimethylamino-1-thio-4-trimethylsilyl-sulfano- 1λ5, 2λ3-diphosphet-3-ene 6b , nearly quantitatively within several days at +20°C. 相似文献
3.
The o-quinoid 8π electron system 2 , generated by thermal ring opening of benzothiete ( 1 ), enters regio-specific [8π + 2π] cycloaddition reactions with electron-deficient nitriles 3a-d , yielding the 4H-1,3-benzothiazines 4a-d. A competitive dimerization of 1 leads to 1,5-dibenzo[b,f]dithiocin (5). Depending on the nitrile further competitive or subsequent reactions (2 + 3b → 7b, 2 + 3d → 4d → 8d) can occur. The cycloadducts 10e and 11e gained from 3e anticipate a primary cleavage of 3e to methylisothiocyanate 9e which reacts at the C?N double bond as well as at the C?S double bond. 相似文献
4.
A series of binuclear complexes [{Cp*Ir(OOCCH2COO)}2(pyrazine)] ( 1 b ), [{Cp*Ir(OOCCH2COO)}2(bpy)] ( 2 b ; bpy=4,4′‐bipyridine), [{Cp*Ir(OOCCH2COO)}2(bpe)] ( 3 b ; bpe=trans‐1,2‐bis(4‐pyridyl)ethylene) and tetranuclear metallamacrocycles [{(Cp*Ir)2(OOC‐C?C‐COO)(pyrazine)}2] ( 1 c ), [{(Cp*Ir)2(OOC‐C?C‐COO)(bpy)}2] ( 2 c ), [{(Cp*Ir)2(OOC‐C?C‐COO)(bpe)}2] ( 3 c ), and [{(Cp*Ir)2[OOC(H3C6)‐N?N‐(C6H3)COO](pyrazine)}2] ( 1 d ), [{(Cp*Ir)2[OOC(H3C6)‐N?N‐(C6H3)COO](bpy)}2] ( 2 d ), [{(Cp*Ir)2[OOC(H3C6)‐N?N‐(C6H3)COO](bpe)}2] ( 3 d ) were formed by reactions of 1 a – 3 a {[(Cp*Ir)2(pyrazine)Cl2] ( 1 a ), [(Cp*Ir)2(bpy)Cl2] ( 2 a ), and [(Cp*Ir)2(bpe)Cl2] ( 3 a )} with malonic acid, fumaric acid, or H2ADB (azobenzene‐4,4′‐chcarboxylic acid), respectively, under mild conditions. The metallamacrocycles were directly self‐assembled by activation of C? H bonds from dicarboxylic acids. Interestingly, after exposure to UV/Vis light, 3 c was converted to [2+2] cycloaddition complex 4 . The molecular structures of 2 b , 1 c , 1 d , and 4 were characterized by single‐crystal x‐ray crystallography. Nanosized tubular channels, which may play important roles for their stability, were also observed in 1 c , 1 d , and 4 . All complexes were well characterized by 1H NMR and IR spectroscopy, as well as elemental analysis. 相似文献
5.
The optimized geometries and energies of fluorine-substituted ethylene dications C2HnF4-n 2+ (n = 0–4) have been investigated by means of ab initio methods. At the MP3/6-31G**//6-31G* + zero-point energy level of theory, the results predict that C2F42+ and C2HF32+ are planar, while C2H42+, C2H3F2+ and 1,1—C2H2F22+ prefer a perpendicular geometry. For 1,2—C2H2F22+ an energy difference of only 0.3 kcal/mol is found between the (trans) planar and perpendicular structure. The stabilizations attributed to hyperconjugation, fluorine lone-pair donation, and (C? F) double-bond conjugation are discussed. A comparison is made for the C? C and C? F stretching frequencies determined at 6-31G*//6-31G* between the neutral and dicationic species. The theoretically determined ionization energies for the vertical process N+ → N2+ at the MP3/6-31G*//3-21G level are compared with experimental Qmin values. 相似文献
6.
Acyl-and Alkylidenephosphines. XXVI. 2, 4-Bis (phenylimino)-1, 3-diphosphetanes from Thiocarbamoyl- and Carbamoyltrimethylsilylphosphines . Bis(trimethylsilyl)phosphines R? P[? Si(CH3)3]2 1 (R = H3C a, H5C6 b, (H3C)3C e, H11C9 d) and phenyl isothiocyanate give insertion compounds which were identified as [CN-phenyl, N-trimethylsilyl)thiocarbamoyl]trimethylsilylphosphines 3 ? 2 in solution as well as in the solid state [2]. In the presence of small amounts of solid sodium hydroxide the phenyl derivative 3 ? 2b eliminates bis(trimethylsilyl) sulfane, whereas the tert-butyl 3 ? 2c and the mesityl compound 3 ? 2d show the same reaction even without a catalyst. The unstable [(phenylimino)methylidene]phosphines 6 formed first, dimerize rapidly to give 2, 4-bis(phenylimino)-1,3-diphosphetanes 7 which in solution exist as mixtures of the E and Z isomers. Via a NaOH-catalyzed elimination of hexamethyldisiloxane these cyclic phosphines 7 can also be obtained from the adducts of phenyl isocyanate and bis(trimethylsilyl)phosphines 1. Taking the thermally sufficiently stable tert-butyl derivative 7 c as an example, the temperature dependence of n.m.r. spectra is discussed in detail. 相似文献
7.
In completely stereospecific [4+2] cycloadditions, the perfluorinated selenocarbonyls 1 and 2 react both with trans‐trans‐2, 4‐hexadiene and cis‐trans‐2, 4‐hexadiene to yield 3, 6‐dihydro‐cis‐3, 6‐dimethyl‐2H‐selenapyrans 3 , 4a and 4b . The observed stereoselectivity leads to the conclusion, that the [4+2] cycloaddition of perfluorinated selenocarbonyls follows a concerted pathway. An identical mixture of isomers was isolated when using the precursor for 2 , trimethylstannyl (pentafluoroethyl)selane, which reacts with both 1, 3‐dienes over several weeks to form a mixture of syn‐2‐fluoro‐3, 6‐dihydro‐cis‐3, 6‐dimethyl‐2‐trifluoromethyl‐2H‐selenapyran ( 4a ) and anti‐2‐fluoro‐3, 6‐dihydro‐cis‐3, 6‐dimethyl‐2‐trifluoromethyl‐2H‐selenapyran ( 4b ) in the same ratio as found for 2 , thus proving the intermediate formation of Se=C(F)CF3 ( 2 ). Complex 2D NMR experiments were used to distinguish the isomers 4a and 4b and to assign the 1H, 13C and 19F NMR data of the selenaheterocycles. 相似文献
8.
Nitric Oxide Insertion Reactivity with the Bismuth–Carbon Bond: Formation of the Oximate Anion, [ON(C6H2tBu2O)]−, from the Oxyaryl Dianion, (C6H2tBu2O)2−
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Dr. Douglas R. Kindra Dr. Ian J. Casely Dr. Joseph W. Ziller Prof. William J. Evans 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15242-15247
The first example of NO insertion into a Bi?C bond has been found in the direct reaction of NO with a Bi3+ complex of the unusual (C6H2tBu2‐3,5‐O‐4)2? oxyaryl dianionic ligand, namely, Ar′Bi(C6H2tBu2‐3,5‐O‐4) [Ar′=2,6‐(Me2NCH2)2C6H3] ( 1 ). The oximate complexes [Ar′Bi(ONC6H2‐3,5‐tBu2‐4‐O)]2(μ‐O) ( 3 ) and Ar′Bi(ONC6H2‐3,5‐tBu2‐4‐O)2 ( 4 ) were formed as a mixture, but can be isolated in pure form by reaction of NO with a Bi3+ complex of the [O2C(C6H2tBu2‐3‐5‐O‐4]2? oxyarylcarboxy dianion, namely, Ar′Bi[O2C(C6H2tBu2‐3‐5‐O‐4)‐κ2O,O’]. Reaction of 1 with Ph3CSNO gave an oximate product with (Ph3CS)1? as an ancillary ligand, (Ph3CS)(Ar′)Bi(ONC6H2‐3,5‐tBu2‐4‐O) ( 5 ). 相似文献
9.
Triclinic single crystals of [(C6H10)(NH3)2][Ni(H2O)4C6H2(COO)4]·4H2O have been prepared in aqueous solution at 55 °C. Space group (Nr. 2), a = 691.23(6), b = 924.84(5), c = 1082.43(7) pm, α = 74.208(6)°, β = 75.558(7)°, γ = 68.251(6)°, V = 0.60985(7) nm3, Z = 1. The Nickel(II) species, located on a crystallographic inversion centre, is coordinated in a trans‐octahedral fashion by two oxygen atoms stemming from the centrosymmetric pyromellitate anions and four from water molecules (Ni–O 205.82(12) – 208.11(13) pm). The connection between Ni2+ and [C6H2(COO)4)]4? leads to infinite chain‐like polyanions extending parallel to with {Ni(H2O)4[C6H2(COO)4]2?}n composition. [(C6H10)(NH3)2]2+‐cations are accomodated between the chains, compensating for the negative charge of the polyanions. Thermogravimetric analysis in air showed that the loss of water of crystallisation occurs in two steps between 102 and 206 °C, corresponding to the loss of 6 and 2 water molecules per formula unit, respectively. The dehydrated sample was stable between 206 and 353 °C. Further decomposition yielded nickel(II) oxide (NiO). 相似文献
10.
Synthesis and Crystal Structure of the Lithium Strontium Hydride Nitride LiSr2H2N LiSr2H2N was synthesized by the reaction of LiH and Li3N with elemental strontium in sealed tantalum tubes at 650 °C within seven days. This second example of a quaternary hydride nitride crystallizes orthorhombically in space group Pnma (no. 62) with the lattice constants a = 747.14(5) pm, b = 370.28(3) pm and c = 1329.86(9) pm (Z = 4). Its crystal structure contains both kinds of anions H? and N3? in a sixfold distorted octahedral metal cation coordination each. The coordination polyhedra [(H1)Sr5Li]10+, trans‐[(H2)Sr4Li2]9+ and [NSr5Li]8+ are connected via edges and corners to form a three‐dimensional network. Two crystallographically different Sr2+ cations exhibit a sevenfold monocapped trigonal prismatic coordination by H? and N3? with [(Sr1)H5N2]9? and [(Sr2)H4N3]11? polyhedra, wheras Li+ shows a nearly planar fourfold coordinative environment ([LiH3N]5?). Cationic double chains of edge‐shared [NSr5Li]8+ octahedra dominate the structure according to . Running parallel to the [0 1 0] direction, they are bundled like a hexagonal rod‐packing which is interconnected by H? anions within the (0 0 1) plane first and finally even in the third dimension (i. e. along [0 0 1]). Therefore the structure of LiSr2H2N is compared to that one of the closely related quaternary hydride oxide LiLa2HO3. 相似文献
11.
Takehiko Nishio 《Helvetica chimica acta》1992,75(2):487-492
A synthetically useful C? C bond formation involving the photochemical addition of quinoxaline-2(1H)-thiones to alkenes is described. Irradiation of the quinoxaline-2(1H)-thiones 1–4 in the presence of the alkenes 7 gave the 2-(2′-mercaptoalkyl)quinoxalines 8–11 in moderate-to-good yields via ring cleavage of an intermediate aminothietane with aromatization of the quinoxaline ring. The latter was formed by [2+2] photocycloaddition of the C?S bond of the quinoxaline-2(1H)-thione and the C?C bond of the alkene. 相似文献
12.
Steffen Dörrich Dr. Jennifer B. Bauer Sabine Lorenzen Christoph Mahler Sarah Schweeberg Dr. Christian Burschka Johannes A. Baus Prof. Dr. Reinhold Tacke Dr. Philip Kraft 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(34):11396-11408
A series of silicon‐containing derivatives of the polycyclic musk odorant galaxolide ( 4 a ) was synthesized, that is, disila‐galaxolide ((4RS,7SR)‐ 4 b /(4RS,7RS)‐ 4 b ), its methylene derivative rac‐ 9 , and its nor analogue rac‐ 10 . The tricyclic title compounds with their 7,8‐dihydro‐6,8‐disila‐6 H‐cyclopenta[g]isochromane skeleton were prepared in multistep syntheses by using a cobalt‐catalyzed [2+2+2] cycloaddition of the mono‐ yne H2C?CHCH2OCH2C?CB(pin) (B(pin)=4,4,5,5‐tetramethyl‐1,3,2‐di‐ oxaborolan‐2‐yl) with the diynes H2C?C[Si(CH3)2C?CH]2 or H2C‐ [Si(CH3)2C?CH]2 as the key step. Employing [Cr(CO)3(MeCN)3] as an auxiliary, the disila‐galaxolide diastereomers (4RS,7SR)‐ 4 b and (4RS,7RS)‐ 4 b could be chromatographically separated through their tricarbonylchromium(0) complexes, followed by oxidative decomplexation. The identity of the title compounds and their precursors was established by elemental analyses and multinuclear NMR spectroscopic studies and in some cases additionally by crystal structure analyses. Compounds (4RS,7SR)‐ 4 b , (4RS,7RS)‐ 4 b , rac‐ 9 , and rac‐ 10 were characterized for their olfactory properties, including GC‐olfactory studies of the racemic compounds on a chiral stationary phase. As for the parent galaxolide stereoisomers 4 a , only one enantiomer of the silicon compounds (4RS,7SR)‐ 4 b , (4RS,7RS)‐ 4 b , rac‐ 9 , and rac‐ 10 , smelt upon enantioselective GC‐olfactometry, which according to the elution sequence is assumed to be also (4S)‐configured as in the case of the galaxolide stereoisomers. The disila‐analogues (4S,7R)‐ 4 b and (4S,7S)‐ 4 b were, however, about one order of magnitude less intense in terms of their odor threshold than their parent carbon compounds (4S,7R)‐ 4 a and (4S,7S)‐ 4 a . The introduction of a 7‐methylene group in disila‐galaxolide ( 4 b →rac‐ 9 ) improved the odor threshold by a factor of two. With the novel silicon‐containing galaxolide derivatives, the presumed hydrophobic bulk binding pocket of the corresponding musk receptor(s) could be characterized in more detail, which could be useful for the design of novel musk odorants with an improved environmental profile. 相似文献
13.
Data on the kinetics of S2F10 pyrolysis, which gives SF4 + SF6, have been reinterpreted to give a value for the equilibrium constant of S2F10 ? SF4 + SF6. This, together with statistical estimates of the entropy and heat capacity of S2F10, can be used to give for this reaction values of ΔH = 19.7 ± 1.0 kcal/mole and ΔS = 47.6 ± 2 gibbs/mole. ΔH(S2F10) = –494 kcal/mole. A compatible mechanism is shown to be S2F10 ? 2SF5 (fast); 2SF5 ? SF6 + SF4 (slow) with step 2 rate-determining. The overall, best first order rate constant is proposed as kmeas = 1017.42–43.0/θ sec?1 = K1k2, where θ = 2.303RT in kcal/mole. Independent measurements of δH and S° for the SF5 radical, permits the evaluation of the equilibrium constant K1 = 108.92–(27.1 ± 6)/θ l./mole-sec and yields k2 = 108.50–15.9/θ l./mole-sec. The observed homogeneous catalysis by NO and CHCl ? CHCl can be explained in terms of a direct abstraction of F from S2F10 : C + S2F10 → CF + S2F9, followed by S2F9 → SF5 + SF4 and SF5 + CF ? SF6 + C (C ? NO or C2H2Cl2). 相似文献
14.
Tetsuro Shimo Hidemi Minamishin Kenichi Somekawa 《Journal of heterocyclic chemistry》1997,34(2):533-536
Dehydrochlorination of chlorinated 5-hydroxy-2-oxabicyclo[3.2.0]heptan-4-ones, 3a-c, which were obtained from the photo[2+2]cycloadditions between 4-hydroxy-3(2H)-furanone 1 and chloroethylenes, with triethylamine gave 2-ethenyl-3(2H)-furanones 4a,b or 2-(2-cyanoethyl)-3(2H)-furanone 4c. 2-Oxa-bicyclo[3.2.0]hept-6-en-4-ones 7 being [2+2]cycloadducts between 1 and acetylenes gave 2,3-dihydro-3-oxooxepin derivatives 8 by electrocyclic rearrangement. 相似文献
15.
Prof. Ying Wang Ping Xu Qiong Xie Qing‐Qing Ma Yan‐Hui Meng Dr. Zi‐Wen Wang Dr. Shaowei Zhang Prof. Dr. Xiao‐Jun Zhao Prof. Dr. Jun Chen Prof. Dr. Zhong‐Liang Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10459-10474
A bidentate ligand, 1‐{4‐[4‐(1H‐1,2,4‐triazol‐1‐yl)phenoxy]phenyl}‐1H‐1,2,4‐triazole (TPPT), has been designed and synthesized. By using TPPT as a building block for self‐assembly with Cd(NO3)2 ? 4 H2O and CdCl2 ? 10.5 H2O, novel 1D double‐chain {[Cd(TPPT)(NO3)2] ? 3 H2O}n ( 1 ) and 2D (4,4) layer [Cd(TPPT)Cl2(H2O)]n ( 2 ) have been constructed. When 1 was employed as a precursor and exposed to DMF or N,N′‐dimethylacetamide (DMAC), the crystals of 1 dissolved and reassembled into two types of brown block‐shaped crystals of 1D double chains: {[Cd(TPPT)2(NO3)2] ? DMF}n ( 1 a ) and {[Cd(TPPT)2(NO3)2] ? DMAC}n ( 1 b ). The anion‐exchange reactions of complex 2 have also been investigated. After gently stirring crystals of 2 in CHCl3/C2H5OH/H2O containing NaBr, NaI ? 2 H2O, or NaOAc ? 3 H2O, the crystals retained their crystalline appearances. A remarkable single crystal to single crystal transformation was observed and 1D double chains of {[Cd(TPPT)Br2] ? C2H5OH}n ( 2 a ) and {[Cd(TPPT)2I2] ? CHCl3}n ( 2 b ), and 1D single chains of [Cd(TPPT)(H2O)2(CH3COO)2]n ( 2 c ), can be obtained. Luminescent properties indicate that 1 shows excellent selectivity for Ca2+ and cyano complexes. To the best of our knowledge, this is the first example of a luminescent probe for Ca2+ based on triazole derivatives. 相似文献
16.
The mass spectra of the fluorinated β-diketones RCOCH2COCF3 (R = Ph, p-FC6H4, p-ClC6H4, p-BrC6H4, p-MeC6H4 and 2-thienyl) and their monothio analogues RC(SH)?CHCOCF3 have been obtained. The replacement of one oxygen by sulphur in the β-diketones brings about a greater complexity in the mass spectra. The β-diketones fragment by first losing a ·CF3 radical and then successively lose CH2?C?O and CO to yield \documentclass{article}\pagestyle{empty}\begin{document}${\rm [R}\mathop {\rm C}\limits^{\rm + } {\rm = O]} $\end{document} and [R]+. The monothio-β-diketones also fragment by an analogous reaction pathway: viz. the initial loss of ·CF3 is followed by the successive loss of CH2?C?O and CS to yield \documentclass{article}\pagestyle{empty}\begin{document}${\rm [R}\mathop {\rm C}\limits^{\rm + } {\rm = S]} $\end{document} and [R]+. However, they also fragment by two other pathways involving the initial loss of ·H and ·X (X=F, Cl, Br, Me), the latter occurring only with those monothio-β-diketones having R=p-XC6H4. 相似文献
17.
The photochemical synthesis of indole derivatives starting from the indoline-2-thiones 1 is described. Irradiation of indoline-2-thiones 1 in the presence of alkenes 3 gave 2-alkyl-3H-indoles 4 – 7 or 2-alkylindoles 8 – 22 through the ring cleavage of the intermediates, spirocyclic amino-thietanes, initially derived by [2 + 2] cycloaddition of the C?S bond of 1 and the C?C bond of 3 . Irradiation of 1 in the presence of trialkylamines 26 gave desulfurization products 27 – 32 and unexpected 3-alkylindoles 33 – 40 . N-Acylindoline-2-thiones 11 - p yielded the deacylated products, indoline-2-thiones 1a - b , and ethyl esters 43 through γ-H abstraction by the excited thioamide S-atom when irradiated in CDC13/EtOH or benzene/EtOH. Oxygen analogues 2a - d also underwent intramolecular H abstraction to give the indolin-2-ones 2e – f and ethyl esters 43 in a similar way. 相似文献
18.
Photochemical behaviors of the pyrazinone derivatives 5,6,7,8-tetrahydroquinoxalin-2(1H)-ones 1a – c and 1,5,6,7,8,9-hexahydro-2H-cyclohepta[b]pyrazin-2-one 1d were investigated. Dye-sensitized photo-oxygenation of 1a-c gave the 1:1 adducts 5a – c of the corresponding 3,8a-epidioxy-3,5,6,7,8,8a-hexahydroquinoxalin-2(1H)-one 4 and H2O, whereas 1d gave 3,9a-epidioxy-1,3,5,6,7,8,9,9a-octahydro-2H-cyclohepta[b]pyrazin-2-one 4d (Scheme 2). The different kind of products was interpreted as being the result of the ring strain and steric hindrance of endoperoxides produced from 1a – d with singlet oxygen. Irradiation of 1a – b in the presence of alkenes gave tricyclic azetidine derivatives 9 by [2 + 2] cycloaddition of the C?N bond of 1 to the alkene. 相似文献
19.
Guibin Ma Andrey Ilyukhin Julius Glaser 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):1473-1475
The title compound, [H2bipy](ClO4)2 or C10H10N22+·2ClO4?, was obtained at the interface between an organic (2,2′‐bipyridine in methanol) and an aqueous phase (perchloric acid in water). The compound crystallizes in space group P and comprises discrete diprotonated trans‐bipyridinium cations, [H2bipy]2+, and ClO4? anions. The cations and anions are connected through N—H?O and C—H?O hydrogen bonds [distances N?O 2.817 (4) and 2.852 (4) Å, and C?O 3.225 (6)–3.412 (5)Å]. The C—C bond distance between the two rings is 1.452 (5) Å. The bipyridinium cation has a trans conformation and the N—C—C—N torsion angle is 152.0 (3)°. 相似文献
20.
Johan K. Terlouw Peter C. Burgers Henk Hommes 《Journal of mass spectrometry : JMS》1979,14(7):387-398
The abundant [C4H5O]+ (m/z 69) ions found in the 70 eV mass spectra of a series of acetylenic, allenylic and unsaturated cyclic ethers are shown to have the following structures: HC?C? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}H? OCH3 (e), H2C?C?—OCH3 (f), (g) and H? C?C? CH2—O\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}H2 (h). Of these, the cyclic ion g is the most stable: its ion enthalpy (≥ 165 kcal mol?1) is close to that found for the acyclic C3H5\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}? O isomers identified in a previous study. Evidence that these four isomeric [C4H5O]+ ions are stable species with lifetimes ≥ 10?5 s is obtained from their collisional activation spectra, the shape of the metastable peaks and the associated kinetic energy release values for the common loss of CO, thermochemical information and analysis of deuterium and carbon-13 labelled precursor molecules. It is further shown that loss of X? from ethers of the type X? C?C? CH2OCH3 involves isomerization into energy rich allenyl type ions [(X)HC?C?CHOCH3]+˙ . These ions undergo loss of X? by simple bond cleavage, yielding, e type product ions, when the C? X bond strength is relatively low (X?I, Br). When X?Cl and especially CH3 or H, X? is only lost after rearrangement yielding the cyclic product ion g. The mechanism for this cyclization reaction is related to that proposed in a previous study for the ester→ acid isomerization in the molecular ions of the esters of α, β-unsaturated carboxylic acids. 相似文献