Theoretical study on interactions between thiophene/dibenzothiophene/cyclohexane/toluene and 1-methyl-3-octylimidazolium tetrafluoroborate

It is critically important to understand the interactions between thiophene/dibenzothiophene/cyclohexane/toluene and 1-methyl-3-octylimidazolium tetrafluoroborate ([C8MIM]⁺[BF₄]^?) due to desulfurization by ionic liquids. In this work, the structures of thiophene, dibenzothiophene, cyclohexane, toluene, [C8MIM]⁺[BF₄]^?, [C8MIM]⁺[BF₄]^?-thiophene, [C8MIM]⁺[BF₄]^?-dibenzothiophene, [C8MIM]⁺[BF₄]^?-cyclohexane, and [C8MIM]⁺[BF₄]^?-toluene were optimized systematically at the GGA/PW91/DNP level, and the most stable geometries were performed by NBO and AIM analyses. It was found that [BF₄]^? anion tends to locate near C2–H2 and four hydrogen bonds between [C8MIM]⁺ and [BF₄]^? form in [C8MIM]⁺[BF₄]^?. There exist hydrogen bonds and C–H···π interactions between [C8MIM]⁺[BF₄]^? and thiophene/cyclohexane/toluene, while the hydrogen bonding interactions, π···π and C–H···π interactions occur between [C8MIM]⁺[BF₄]^? and dibenzothiophene confirmed by NBO and AIM analyses. The interaction energies between [C8MIM]⁺[BF₄]^? and thiophene, dibenzothiophene, cyclohexane, toluene are 18.83, 20.93, 6.83, 12.99 kcal/mol, showing the preferential adsorption of dibenzothiophene and thiophene by ionic liquid, in agreement with the experimental results of dibenzothiophene and thiophene extraction by [C8MIM]⁺[BF₄]^?.     

Nucleophilic substitution reactions of acetylides on substituted tricarbonyl(η6-fluoroarene)chromium and reactions of tricarbonyl[η6-(2-trimethylsilylethynyl)toluene]chromium and tricarbonyl[η6-(p-ethynyl-phenylethynyl)benzene]chromium with dicobalt octacarbonyl

Nucleophilic substitution reactions of various acetylides on substituted tricarbonyl(η⁶-fluoroarene)chromiums were pursued. The reaction presumably underwent a more complicated mechanism rather than the direct substitution on the fluorine-bearing carbon. The organometallic compounds (η⁶-C₆H₃R¹R²R³)Cr(CO)₃ (R¹: CC–C₆H₄CH₃, R²: o-Me, R³: H (5a), R¹: CC–C₆H₄CH₃, R²: o-OMe, R³: H (6a), R¹: CC–C₆H₄CH₃, R²: m-OMe, R³: H (6b), R¹: CCPh, R²: o-Me, R³: o-OMe (8b), R¹: CCPh, R²: m-Me, R³: m-OMe (8c), R¹: CCSiMe₃, R²: o-Me, R³: H (9a), R¹: CC–C₆H₄CCH, R²: H, R³: H (12), R¹: CC–C₆H₄CCH, R²: o-Me, R³: H (13)) as well as the organometallic dimmer [{(η⁶-o-Me-C₆H₄)Cr(CO)₃(di-ethynyl)] (di-ethynyl: CC–C₆H₄CC (14)) have been synthesized from nucleophilic substitution reactions of tricarbonyl(η⁶-fluoroarene)(chromium) compounds with suitable acetylides. The products have been characterized by spectroscopic means. In addition, (8b) and (8c) were characterized by X-ray diffraction studies. Further reactions of (9a) and (12) with appropriate amount of Co₂(CO)₈ yielded μ-alkyne bridged bimetallic complexes, Co₂(CO)₆{μ-Me₃SiCC–(o-tolueneCr(CO)₃} (10) and (Co₂(CO)₆)₂{μ-HCC–C₆H₄–CC–(benzene)Cr(CO)₃)}(15), respectively. Both (10) and (15) were characterized by spectroscopic means as well as single crystal X-ray crystallography. The core of these molecules is quasi-tetrahedron containing a Co₂C₂ unit. A two-dicobalt-fragments coordinated di-enyls complex, (Co₂(CO)₆)₂{μ-HCC–C₆H₄–CC–H} (17), was synthesized from the reaction of 1,3-diethynylbenzene with Co₂(CO)₈. Crystallographic studies of (17) also show that it exhibits a distorted Co₂C₂ quasi-tetrahedral geometry.     

Nucleophilic addition of aromatic amide oximes to [2-B<Subscript>10</Subscript>H<Subscript>9</Subscript>NCC<Subscript>2</Subscript>H<Subscript>5</Subscript>]<Superscript>–</Superscript> anion

A series of closo-decaborate anions containing an O-iminoacylamide oxime fragment were synthesized by nucleophilic addition of aromatic amide oximes to 2-propionitrilium closo-decaborate anion. The isolated compounds were characterized by IR, ¹H, ¹³C–{¹H}, and ¹¹B–{¹H} NMR, and mass spectra. The structure of (Ph₄P)[2-B₁₀H₉NH=C(Et)ON=C(NH₂)C₆H₄Me-2] was determined by single-crystal X-ray analysis.     

Mercury forms and their transformation in pyrite under weathering

Pyrite is considered to be the major carrier of mercury in coal. Here, the chemical characteristics of two natural pyrite samples of different weathering degrees were characterized by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Thermal stability of Hg was also analyzed via temperature programmed desorption experiment (TPD). Characteristic ions such as S⁻, Fe⁺, FeS⁻, and FeS₂⁻ were detected on the surface of fresh pyrite. The release temperature of Hg ranged between 180°C and 300°C, and the characteristic peak of black HgS was recorded. In addition, abundant Fe₂O₃⁻, FeSO⁻, SO₄⁻, and HSO₄⁻ were detected on the surface of weathered pyrite, and the release temperature of Hg therein was mainly distributed at 260°C to 380°C and 520°C to 600°C, corresponding to the characteristic peaks of red HgS and HgSO₄, respectively. The results show that pyrite is acidified during weathering and that Hg forms in pyrite are transformed from the original state (HgS) to HgSO₄.     

Isotopic fractionation during pretreatment for accelerator mass spetrometer measurement of (D<Subscript>3</Subscript>C)<Subscript>2</Subscript>O containing <Superscript>14</Superscript>C produced by nuclear reaction

A (D₃C)₂O (d₆-acetone) target was irradiated with semi-monoenergetic neutrons generated from ⁹Be(p,n)⁹B reaction with 20 MeV protons to convert ¹³C and oxygen nuclides in the target into ¹⁴C. With both liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) we measured the (D₃C)₂O (d₆-acetone) liquid targets, which were combustible and easy to afford CO₂ for the AMS measurements. The ¹⁴C yield measured by the LSC method turned out to be 80 times larger than that by the AMS method. This large discrepancy may be attributed to the loss of ¹⁴C atoms during the sample pretreatment in the AMS method such as combustion and cryogenic trapping of CO₂. It means that ¹⁴C newly produced by nuclear reactions can exist in various chemical forms, i.e., C₃D₆O, CO, CO₂, hydrocarbons, etc., and a simple sample pretreatment right after production can cause serious isotopic fractionation. Therefore, using the AMS method, extreme caution in sample pretreatment should be exercised when the ¹⁴C yield produced immediately by nuclear reaction is measured.     

Gas-phase electron diffraction determination of the molecular structure of perfluoro(methyloxirane)

The molecular geometry of perfluoro(methyloxirane) has been studied using gas-phase electron diffraction data, effective least-squares refinement of the structure being achieved with the aid of constraints to limit the number of variable parameters. With the CCF₃ bond constrained to be 0.078 Å longer than the ring CC, the refined bond- length values CF (av.) = 1.323(2), CO (av.) = 1.410(8), and CC (ring) = 1.467(7) Å ($\text{r}$_g values, with e.s.d. in parentheses) were obtained; the angles between ring bonds and substituent CF bonds were CCF (av.) 121(1) and OCF (av.) 114(1)^o, the corresponding parameters involving the bulkier CCF₃ fragment being larger by 3^o in each case [∠CCCF₃ 124(1)^o∠OCCF₃ 117(2)^o]. The remaining refined parameters were ∠CCF(of CF₃) = 110.6(4)^o and τ , a torsion angle defining the orientation of the CF bonds of the CF₃ group with respect to ring bonds, = 29(2)^o. Dependent bond angles possessed the values 62.7 (COC), 58.7 [OCC (ring)], 108.3 [FCF (CF₃ group)], 114 [FCF (ring CF₂)], and 111^o (FCCF₃).     

Self-Assembly of a Redox Active,Metallosupramolecular [Pd3L6]6+ Complex Using a Rotationally Flexible Ferrocene Ligand

A new ferrocene-containing [Pd₃( L_4EFc )₆]⁶⁺(X⁻)₆ ( C ⋅ BF₄ and C ⋅ SbF₆ where X=BF₄⁻ or SbF₆⁻) self-assembled double-walled triangle has been synthesized from the known, rotationally flexible, 1,1′-bis(4-pyridylethynyl)ferrocene ligand ( L_4EFc ), and characterized by ¹H, ¹³C and diffusion ordered (DOSY) NMR spectroscopies, high-resolution electrospray ionization mass spectrometry (HR−ESI−MS), X-ray crystallography and cyclic voltammetry (CV). The molecular structures confirmed that double-walled triangle cage systems ( C ⋅ BF₄ and C ⋅ SbF₆ ) were generated. C ⋅ BF₄ was shown to interact with the anionic guest, p-toluenesulfonate. CV experiments revealed that the triangles were redox active, however addition of the guest did not influence the redox potentials.     

2J(P,C) and 3J(P,C) Coupling Constants in Some New Phosphoramidates. Crystal Structures of CF3C(O)N(H)P(O)[N(CH3)(CH2C6H5)]2 and 4‐NO2‐C6H4N(H)P(O)[4‐CH3‐NC5H9]2

Some new phosphoramidates were synthesized and characterized by ¹H, ¹³C, ³¹P NMR, IR spectroscopy and elemental analysis. The structures of CF₃C(O)N(H)P(O)[N(CH₃)(CH₂C₆H₅)]₂ ( 1 ) and 4‐NO₂‐C₆H₄N(H)P(O)[4‐CH₃‐NC₅H₉]₂ ( 6 ) were confirmed by X‐ray single crystal determination. Compound 1 forms a centrosymmetric dimer and compound 6 forms a polymeric zigzag chain, both via ‐N‐H…O=P‐ intermolecular hydrogen bonds. Also, weak C‐H…F and C‐H…O hydrogen bonds were observed in compounds 1 and 6 , respectively. ¹³C NMR spectra were used for study of ²J(P,C) and ³J(P,C) coupling constants that were showed in the molecules containing N(C₂H₅)₂ and N(C₂H₅)(CH₂C₆H₅) moieties, ²J(P,C)>³J(P,C). A contrast result was obtained for the compounds involving a five‐membered ring aliphatic amine group, NC₄H₈. ²J(P,C) for N(C₂H₅)₂ moiety and in NC₄H₈ are nearly the same, but ³J(P, C) values are larger than those in molecules with a pyrrolidinyl ring. This comparison was done for compounds with six and seven‐membered ring amine groups. In compounds with formula XP(O)[N(CH₂R)(CH₂C₆H₅)]₂, ²J(P,CH₂)_benzylic>²J(P,CH₂)_aliphatic, in an agreement with our previous study.     

Formation and structure of diruthenium complexes Ru2(CO)6−n (PPh3) n {μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} (n=1, 2)

Ruthenium carbonyl triphenylphosphine complexes Ru₂(CO)_6−n (PPh₃) _n {μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} (n=1, 2) were obtained by the reaction of complex Ru₂(CO)₆{μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} containing the ruthenacyclopentadiene moiety with PPh₃ in refluxing toluene. The complexes were characterized by IR and by¹H,¹³C, and³¹P NMR spectroscopy, and by X-ray analysis. The monophosphine derivative is identical to the complex formed by fragmentation of the Ru₃(CO)₈(PPh₃){μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} cluster and contains the PPh₃ ligand at the ruthenium atom of the ruthenacyclopentadiene moiety. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1836–1843, September, 1998     

Experimental and theoretical study of <Superscript>13</Superscript>C shielding tensors in new-style molybdenum complex

¹³C 2D-PASS spectra of two new cis-dioxo catecholatomolybdenum complexes (NH₂CH₂NH₂CHCH₂)₂(H⁺)₃[Mo^vO ₂(C₆H₄O₂)₂] and (NH₂CH₂CH₂CH₂NH₂)₂(H⁺)₃[Mo^(v)O₂ (C₂H₂O₂)₂] have been obtained by solid-state nuclear magnetic resonance (NMR), in which the spinning sidebands were well-separated. The principal components of the ¹³C shielding tensors were extracted by theoretically fitting the intensities of ¹³C spinning sidebands. The effects of counter cations on ¹³C chemical shift isotropy and shielding tensor of cis-dioxo catecholatomolybdenum complex anion [Mo ^(v)O₂(C₆H₄O₂)₂]³⁻ were studied, comparing the ¹³C CSA of those carbon sites in complex anions with that of the counter cations. Based on the known structure of the molybdenum complex crystal, theoretical values of ¹³C shielding tensors were calculated by the ainitio GIAO method, in comparison with the experimental results.     

Synthesis and multinuclear NMR data of the ferrocenes (Me3Ecp)2Fe (E = C,Si, Ge,Sn, Pb)

The substituted cyclopentadienyl anions Me₃Ecp⁻ with E = C, Si, Ge, Sn, Pb have been prepared from either the mono- or disubstituted cyclopentadienes, including the hitherto unknown (Me₃Pb)₂C₅H₄. Representative examples have been characterized by ¹³C NMR spectroscopy. Treatment with iron(II) chloride yielded the ferrocenes (Me₃Ecp)₂Fe, which have been investigated by ¹H, ¹³C, ²⁹Si, ¹¹⁹Sn, and ²⁰⁷Pb NMR spectroscopy. ¹³C¹³C coupling and selective proton decoupling were used for the assignment of the ¹³C and ¹H signals. The shifts δ(¹³C) reflect the electron-releasing or -withdrawing power of the substituents Me₃E, but the isotope shifts ¹Δ¹³C(i)(¹³C(j)) do not show a similar trend. There is evidence that δ(¹¹⁹Sn) and δ(²⁰⁷Pb) are influenced by the coordination. The analysis of the coupling constants reveals that ¹J(¹³C(1)¹³C(2/5)) varies with the electronegativity of E. Because of the small range (4.5–5.0 Hz) of ¹J(⁵⁷Fe¹³C) the effect of E is apparent only when E = C is replaced by E = Si. As for the coupling between E and ¹³C or ¹H, the square root of the reduced coupling constant K is related linearly to the atomic number of E; exceptions are ¹K(²⁰⁷Pb¹³C).     

Synthesis and reactions of phenyliodonium bis(perfluoroalkanesulfonyl) methides

Phenyliodonium bis(perfluoroalkanesulfonyl) methides PhI⁺ ⁻C(SO₂R_F)₂ ( 3 ) were prepared by the reaction of bis(perfluoroalkanesulfonyl)methanes with diacetoxyiodobenzene. The photochemical reactions of 3 with alkenes, methanol, bromine, and benzene gave the corresponding addition or insertion products. When 3 was irradiated in the presence of methyl sulfide, pyridine, and triphenylphosphine, it afforded the ylides containing the bis(perfluoroalkanesulfonyl)methylene functionality, Y⁺ ⁻C(SO₂R_F)₂. In these reactions the bis(perfluoroalkanesulfonyl)carbene intermediate (R_FSO₂)₂C: may be involved. Irradiation or heating of 3 in DMSO gave a 1 : 1 complex, the structure of which was confirmed by X-ray diffraction analysis. Bis(perfluoroalkanesulfonyl)-methylene dimethyloxosulfonium ylides Me₂(O)S⁺ ⁻C(SO₂R_F)₂ were obtained by air oxidation of bis(perfluoroalkanesulfonyl)methylene dimethylsulfonium ylides.     

Structural Assignments of Ethylidene Acetals by NMR Spectroscopy

The ¹H and ¹³C NMR spectra of ethylidene derivatives of simple diols and of carbohydrates were measured to determine whether NMR parameters could be found which could be related to structure. Four NMR parameters were considered; the chemical shifts of the acetal proton and carbon, the ²J_C,H value between the acetal proton and methyl carbon and the ¹J_C,H value of the acetal carbon. The values,.of these parameters were all somewhat related to ring-size; the ²J_C,H value was most closely related. The sign of ²J_C,H was shown to be positive for 2-methy l-l,3-dioxolane and Z-methy l-l,3-dioxane by means of selective population transfer experiments. Comparison of the ¹³C NMR chemical shifts of the acetal with the parent diol was found to give information about acetal location.     

LiFePO4/C composites from carbothermal reduction method

Using the cheap raw materials lithium carbonate, iron phosphate, and carbon, LiFePO₄/C composite can be obtained from the carbothermal reduction method. X-ray diffraction (XRD) and scanning electronic microscope (SEM) observations were used to investigate the structure and morphology of LiFePO₄/C. The LiFePO₄ particles were coated by smaller carbon particles. LiFePO₄/C obtained at 750 °C presents good electrochemical performance with an initial discharge capacity of 133 mAh/g, capacity retention of 128 mAh/g after 20 cycles, and a diffusion coefficient of lithium ions in the LiFePO₄/C of 8.80?×?10^?13 cm²/s, which is just a little lower than that of LiFePO₄/C obtained from the solid-state reaction (9.20?×?10^?13 cm²/s) by using FeC₂O₄ as a precursor.     

Darstellung und Kristallstruktur der Calciumnitridhalogenide Ca2NCl und Ca2NBr

Preparation and Crystal Structure of the Calcium Nitride Halides Ca₂NCl and Ca₂NBr Ca₂NCl and Ca₂NBr were prepared as well crystalline powders of light-grey colour by reaction of Ca₃N₂ and CaX₂ in a molar ratio 1:1 in steel ampoules under argon (50 h 740°C; 15 h 1 000°C and 40 h 950°C, resp.). Brownish transparent single crystals were obtained by annealing specimens in molybdenum ampoules (25 d 1 125°C). The compounds crystallize in the anti-α-NaFeO₂-structure (Crystallographic data: see “Inhaltsübersicht”). N^3? and X^? are rhombohedrally distorted cubic close packed. The sequence of the anionic layers is X^?? N^3?? X^?? N^3?? …?. Ca²⁺ is shifted towards N^3? so that Ca₂N⁺ layers are formed which are held together by the halide ions.     

Synthesis of La(III), Y(III) complexes with polyglycol aldehyde-amino acid Schiff base and their high resolution solid state13C NMR spectra

La (III), Y(III) complexes wit11 diglycol aldehyde his-arginine (H₂DAAR) and tetraglycol aldehyde bislysine (H₂TALY) Schiff bases were synthesized. Thcy were characterized and formulated as La (H₂DAAR) (NO₃)₃. 6H₂0 and Y (H₂TALY) (NO₃)₃. 5H₂0 separately by elemental analyses. The obtained complexes were investigated in detail by high resolution solid state (HRSS)¹³C NMR using cross polarization, magic angle spinning (CPMAS). and total suppression of sidebands (TOSS) techniques. The results are supported by the liquid state 2D-’H-¹³C COSY NMR spectra. Some new information about the splitting peaks of¹³C for -CH = N- group and alkene carbon bands, etc. in HRSS¹³C NMR spectra are given.     

Solid‐State NMR Investigations on the Amorphous Network of Precursor‐Derived Si2B2N5C4 Ceramics

Employing a multitude of modern solid state NMR techniques including ¹³C{¹⁵N}REDOR NMR, ¹H–¹³C CP NMR, ¹¹B MQMAS NMR spectroscopic experiments, the structural organization of Si₂B₂N₅C₄ ceramic has been studied. The experiments were executed on double isotope enriched (¹³C, ¹⁵N) and natural isotope abundance Si₂B₂N₅C₄ ceramics. The materials were synthesized by aminolysis and subsequent pyrolysis of intermediate pre‐ceramic polymers that were obtained from the single source precursor TSDE, 1‐(trichlorosilyl)‐1‐(dichloroboryl)ethane (Cl₃Si–CH(CH₃)–BCl₂). The result of the ¹³C{¹⁵N} REDOR NMR spectroscopic experiment shows that carbon atoms are incorporated into the network by bridging to nitrogen, which already occurs during the polymerization step. Furthermore, the combined results of ¹¹B NMR and ¹¹B MQMAS NMR indicate that boron atoms may also be connected to carbon in addition to nitrogen.     

η1-Alkynylplatinum(II) complexes with cycloocta-1,5-diene and tri(1-cyclohepta-2,4,6-trienyl)phosphane ligands

η¹-Alkynylplatinum(II) complexes of the type (cod)Pt(CCR)₂ (1, cod=η⁴-cycloocta-1,5-diene; R=Me (a), ^tBu (b), Ph (c), Fc (d), SiMe₃ (e)) were prepared in good yields from the reaction of (cod)PtCl₂ with either HCCR and NaOEt (R=^tBu, Ph, Fc) or di(1-alkynyl)dimethyltin, Me₂Sn(CCR)₂ (R=Me, SiMe₃). The analogous reaction of [P]PtCl₂ ([P]=tri(1-cyclohepta-2,4,6-trienyl)phosphane, {P(C₇H₇)₂(η²-C₇H₇)}) with Me₂Sn(CCR)₂ (R=Me, ^tBu, Ph, Fc, SiMe₃), afforded selectively the complexes [P]PtCl(CCR) 2a–e in high yield, in which the 1-alkynyl group is in cis position with respect to the phosphorus atom, and one of the C₇H₇ rings is η²-coordinated to platinum through the central CC bond. Complexes 3a–e of the type [P]Pt(CCR)₂ could not be prepared by the reaction of 2 with an excess of the 1-alkynyltin reagents. However, the reaction of 1 with the phosphane P(C₇H₇)₃ gave compounds 3a–e in quantitative yield by substitution of the cod ligand. The molecular structures of 2b and 3d were determined by X-ray structure analysis, and complexes 1–3 were characterised in solution by multinuclear magnetic resonance spectroscopy (¹H-, ¹³C-, ²⁹Si-, ³¹P-, ¹⁹⁵Pt-NMR). The structures of 2 and 3 in solution were found to be fluxional with respect to coordination of the C₇H₇ rings to platinum.     

Use of 13C isotope shifts for assignment of deuterium labelling sites in 1,3-diphenylpropan-1-one

¹³C NMR spectroscopy was used for the unequivocal analysis of the mixture of products of RuCl₂[P(C₆H₅)₃]₃-catalysed transfer deuteriation of benzylideneacetophenone by (a) DCOONa/H₂O, (b) HCOONa/D₂O and (c) DCOONa/D₂O. Signal assignments in the ¹³C spectra were obtained mainly from the deuterium-induced ¹³C isotope shifts. The geminal ¹³C? ²H shift of the β-carbon of deuteriated 1,3-diphenylpropan-1-one is almost twice that for the α-carbon.     

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.