The mass spectra of organic compounds. 7th Communication. 4,4-Dimethyl-1-pentene

Loss of CH, CH₄, C₂H₄, C₃H, C₃H₆ and C₃H₇ from the molecular ions of a number of ¹³C-labeled analogs of 4,4-dimethyl-1-pentene was studied both in normal (source) 70-eV electron impact (EI) spectra dn in metastable spectra. For loss of CH in the source, 96% of the methyl comes frm positions of 5, 5′ and 5″, while the remainder comes from position 1. In the metastable spectra, loss of C-1 (16%) and C-3 (9%) is increasing in importance. The loss of ethylene is a particular case: either C-1 or C-3 are lost with any other C-atom from positions 2,5,5′, and 5″ (8 × 10%) in the metastable spectra, the probability for simultaneous loss of C-1 and C-3 being 6%. If C-1 seems to these two positions become completely equivalent in the metastable time range. The T-values (kinetic energy release) for the different positions show small, but statisticaly different values and a small isotope effect. Loss of C₃H₅ (allylic cleavage) is 100% C-1, C-2 and C-3, i.e., no evidence for skeletal rearrangement is seen. This is also true for loss of C₃C₆ (McLafferty rearrangement) within the source, but in metastable decay the other positions gain in importance. The neutral fragment C₃H appears to be the the result of consecutive loss of CH and C₃H₄, rather than a one-step loss of propyl radical or the inverse reactions sequence. No metastable reaction can be seen for this reaction. Decomposition of labeled C₆H and C₅H secondary ions occurs in an essentially random fashion.     

The structures,thermochemistry, and electron affinities of hydrogenated silicon clusters Si6Hn/Si6H (n = 3–14)

The hydrogenated silicon clusters structures, electron affinities, and dissociation energies of the Si₆H_n/Si₆H (n = 3?14) species have been systematically investigated by means of three density functional theory (DFT) methods. The basis set used in this work is of double‐ζ plus polarization quality with additional diffuse s‐ and p‐type functions, denoted DZP++. The geometries are fully optimized with each DFT method independently. Three different types of energy separations presented in this work are the adiabatic electron affinity (EA_ad), the vertical electron affinity (EA_vert), and the vertical detachment energy (VDE). The first Si? H dissociation energies D_e (Si₆H_n→ Si₆H_n?1+H) for the neutral Si₆H_n and D_e (Si₆H→Si₆H+H) for the anionic Si₆H species have also been reported. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

Aromaticity of ionic structures: Investigation and application of NICS value and 4n + 2 rule

At DFT/B3LYP/6‐31G** theoretical level, C₆H and C (n = 0, ?2, and +2), C₆H and C (n = 0, ±2, ±4, and ±6), C₆H (n = 0–6), as well as C₆H₆‐A and C₆‐A (A = Be, B, N, O, Mg, Al, Si, S, and Fe) structures were investigated. Comparing NICS values of C₆H and C (n = 0, ?2, and +2), we discovered that C₆H, C₆H were antiaromatic, and C₆H₆, C₆, C, C had aromaticity with negative NICS values. According to research of C₆H and C (n = 0, ±2, ±4, ±6), C₆H (n = 0–6), we sustained that their σ and π orbit were different and the locations of electrons were difficult to confirm in ionic structures. Thus, neither 4n + 2 rule nor NICS values can precisely estimate the aromaticity of ionic structures. Besides, through WBI (NBO) research of C₆H₆‐A and C₆‐A (A = Be, B, N, O, Mg, Al, Si, S, and Fe) structures, we found that C₆H₆ was easy to accept electrons, contrarily, C₆ was prone to bestowing electrons. Moreover, C₆H₆ took the symmetrical carbon atoms form feeble interaction or bond, and C₆ used all carbon atoms to impact with other atom. C₆H₆ generated two contrapuntal single bonds with oxygen, sulfur, and nitrogen atoms, whereas C₆ molecule formed double bond with oxygen and nitrogen atoms, two conjoint single bonds with sulfur atom. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Variable-Temperature and Variable-Pressure 17O-NMR Study of Water Exchange of Hexaaquaaluminium(III)

The transverse relaxation rate of H₂O in Al(H₂O) has been measured as a function of temperature (255 to 417 K) and pressure (up to 220 MPa) using the ¹⁷O-NMR line-broadening technique, in the presence of Mn(II) as a relaxation agent. At high temperatures the relaxation rate is governed by chemical exchange with bulk H₂O, whereas at low temperatures quadrupolar relaxation is prevailing. Low-temperature fast-injection ¹⁷O-NMR was used to extend the accessible kinetic domain. The samples studied contained Al³⁺ (0.5 m), Mn²⁺ (0.2–0.5 m), H ⁺ (0.2–3.1 m) and ¹⁷O-enriched (20–40%) H₂O. Non-coordinating perchlorate was used as counter ion. The following H₂O exchange parameters were obtained: k = (1.29 ± 0.04) s⁻¹, ΔH* = (84.7 ± 0.3) kJ mol⁻¹, ΔS* = +(41.6 ± 0.9) J K ⁻¹ mol⁻¹, and ΔV = +(5.7 ± 0.2) cm³ mol⁻¹, indicating a dissociative interchange, I_d, mechanism. These results of H₂O exchange on Al(H₂O) are discussed together with the available complex-formation rate data and permit also the assignment of I_d mechanisms to these latter reactions.     

Silaheterocyklen. III. Erzeugung und Reaktivität von Di-tbutyl-Neopentylsilaethen,BuSiCHCH2But

Silaheterocycles. III. Synthesis and Reactivity of Di-^tbutylneopentylsilaethene, Bu Si?CHCH₂Bu^t The three di-^tbutylvinylsilanes BuSi(X)CH?CH₂ (X = H 5 , X = F 9 , X = Cl 22 ) are prepared by the reaction of their SiCl precursors with vinyl lithium. In the treatment with LiBu^t the first step is the generation of the α-lithio compound BuSi(X)CH(Li)CH₂Bu^t, the following reactions are governed by the nature of the substituent X and the reaction conditions (solvent, concentration, temperature). For X = H 2,3-LiH elimination leads to BuSi(H)CH?CHBu^t ( 7 ), with X = F or Cl Si?C formation by 1,2-LiX elimination competes with intermolecular Si-C-coupling producing BuSi(H)CH(SiBuCH?CHBu^t)CH₂Bu^t ( 13 ) as the main product. BuSi?CHCH₂Bu^t ( 1 ) probably coordinates to LiBu^t and reacts to yield BuSiCH?CHBu^t ( 3 ) and 7 , forms tetrabutyl-dineopentyl-1,3-disilacyclobutane 2 by cyclodimerization and 13 by addition of BuSi(X)CH(Li)CH₂Bu^t.     

Lactide polymerization activity of alkoxide,phenoxide, and amide derivatives of yttrium(III) arylamidinates

In quest of new, single‐site catalysts for cyclic ester polymerizations, a series of mononuclear yttrium(III) complexes of N,N′‐bis(trimethylsilyl)benzamidinate ([L^TMS]⁻) and hindered N,N′‐bis‐(2,6‐dialkylaryl)toluamidinates ([L^Et]⁻, aryl = Et₂C₆H₃, and [L^iPr]⁻, aryl = ⁱPr₂C₆H₃) were synthesized and characterized by X‐ray diffraction: LY(μ‐Cl)₂Li(TMEDA) ( 1 ), LY(OC₆H₂^tBu₂Me) ( 2 ), LY(OC₆H₃Me₂)₂Li(THF)₄ ( 3 ), LY(μ‐O^tBu)₂Li(THF) ( 4 ), L^iPrY[N(SiMe₂H)₂]₂(THF) ( 5 ), LY(THF)(Cl)(μ‐Cl)Li(THF)₃ ( 6 ), and LY[N(SiMe₂H)₂] ( 7 ). Coordination numbers ranging from five to seven were observed, and they appeared to be controlled by the steric bulk of the supporting amidinate and alkoxide, phenoxide, or amide coligands. Complexes 2 – 5 and 7 are active catalysts for the polymerization of D,L ‐lactide (e.g., with 2 and added benzyl alcohol, 1000 equiv of D,L ‐lactide were polymerized at room temperature in less than 1 h, with polydispersities less than 1.5). The neutral complexes 2 , 5 , and 7 were more effective than the anionic complexes 3 and 4 . In addition, the presence of the more hindered amidinate ligands [L^Et]⁻ and [L^iPr]⁻ on yttrium‐amides slowed the polymerizations ( 7 < 5 < Y[N(SiMe₂H)₂]₃). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 284–293, 2001     

Synthesis and Characterization of the First Bisand Tris[1‐(ω‐alken‐1‐yl)indenyl]lanthanide Complexes

1‐Allyl‐2,4,7‐trimethyl‐1 H‐indene ( 1 ) and 1‐(3‐buten‐1‐yl)‐4,7‐dimethyl‐1 H‐indene ( 2 ), which are to prepare from (2,4,7‐trimethylindenyl)lithium and allyl chloride or from (4,7‐dimethylindenyl)lithium and 4‐bromo‐1‐butene, react with n‐butyllithium yielding (1‐allyl‐2,4,7‐trimethylindenyl)lithium [LiL ( 1 a )] or [1‐(3‐buten‐1‐yl)‐4,7‐dimethylindenyl]lithium [LiL′ ( 2 a )], respectively. The reactions of the trichlorides of gadolinium, erbium, yttrium, lutetium, and ytterbium with 1 a or 2 a (mole ratio 1 : 2) in THF produce the bis(indenyl)lanthanide chloride complexes L₂LnCl(THF) [Ln = Gd ( 1 b ), Er ( 1 c )], LLnCl(THF) [Y ( 2 d ), Lu ( 2 e )], or LYb(μ‐Cl)₂Li(THF)₂ ( 2 f ), whereas the trichlorides of the comparatively large samarium and lanthanum ions react with different molar amounts of 2 a in THF exclusively with formation of the tris(indenyl) complexes LSm ( 2 g ) or LLa(μ‐Cl)Li(Et₂O)₃ ( 2 h ), respectively. All new compounds were characterized by elemental analyses, mass spectrometry, and the diamagnetic compounds 2 d , 2 e and 2 h also by ¹H and ¹³C{¹H}‐NMR spectroscopy. The single crystal X‐ray structural analyses of 1 c , 2 f , 2 g and 2 h demonstrate that the alkenyl groups of the indenyl side chains are not coordinated to the lanthanide atoms.     

Fourier transform ion cyclotron resonance study of the dehydrogenative polymerization of allene and propyne induced by W+ in the gas phase

A Fourier transform ion cyclotron resonance study of the gas-phase reaction of W⁺ with allene is reported. W⁺ successively dehydrogenates at least nine allene molecules, leading to the formation of a series of WC_3nH ions, with WC₂₇H as the largest product observed after a reaction delay of 40 s. Starting from the third reaction, there is a competition between elimination of H₂ and C₂H₂ at each step. The activation of propyne was also investigated and found to lead to essentially the same sequence as with allene. The reaction of W⁺ with 1,1-d₂-allene and collision-induced dissociation spectra of product ions are used to discuss a plausible mechanism for the formation and structures of some of the species observed.     

Theoretical study of one‐electron bonds in a series of high‐spin lithium–beryllium–hydrogen clusters: “Valence shell single‐electron repulsion” rule and electron localization function analysis

A series of high‐spin clusters containing Li, H, and Be in which the valence shell molecular orbitals (MOs) are occupied by a single electron has been characterized using ab initio and density functional theory (DFT) calculations. A first type (⁵Li₂, ⁿ⁺¹LiH_n+ (n = 2–5), ⁸Li₂H) possesses only one electron pair in the lowest MO, with bond energies of ～3 kcal/mol. In a second type, all the MOs are singly occupied, which results in highly excited species that nevertheless constitute a marked minimum on their potential energy surface (PES). Thus, it is possible to design a larger panel of structures (⁸LiBe, ⁷Li₂, ⁸Li, ⁴LiH⁺, ⁶BeH, ⁿ⁺³LiH (n = 3, 4), ⁿ⁺²LiH (n = 4–6), ⁸Li₂H, ⁹Li₂H, ²²Li₃Be₃ and ²²Li₆H), single‐electron equivalent to doublet “classical” molecules ranging from CO to C₆H₆. The geometrical structure is studied in relation to the valence shell single‐electron repulsion (VSEPR) theory and the electron localization function (ELF) is analyzed, revealing a striking similarity with the corresponding structure having paired electrons. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Über Blei (II)-oxidhydrat der Zusammensetzung 3PbO·H2O

Lead oxide hydrate mentioned in the earlier literature with several formulas between PbO · H₂O and PbO · 0.33 H₂O has been synthesized and investigated by high resolution X-ray powder methods, thermogravimetry and infrared spectroscopy. The unit cell was found from 62 powder reflections to be tetragonal with a = 8.009 ± 0.003 Å, c = 9.312 ± 0.005 Å, Z = 12 [PbO · 0.33 H₂O]. These data were confirmed by WEISSENBERG and Precession photographs of single crystals grown as a corrosion product on metallic lead. The space group is D–P4/mnc or C–P4 nc. Thermogravimetric measurements, corrected for a slight content of superficially bound carbon dioxide detected by infrared spectroscopy, lead to the most probable formula 3 PbO · H₂O or PbO · 0.33 H₂O. As infrared spectra show the presence of a HOH deformation vibration, the compound is considered to be an oxide hydrate and not an oxide hydroxide of lead.     

Schwingungsspektroskopische Untersuchungen an den geordneten Perowskiten ABIReVIIO6

Vibrational Spectroscopie Investigations on the Ordered Perovskites A B^IRe^VIIO₆ The vibrational spectra of the ordered perovskites AB^IRe^VIIO₆ with A = Ba, Sr; B = Li, Na are reported. For the cubic Ba compounds the force constants for the ReO₆ octahedra (O_h), the bond order in the Re? O distances have been calculated.     

Structure and dissociation energy of weakly bound H (n = 5−8) complexes

The geometrical parameters, vibrational frequencies, and dissociation energies for H (n = 5–8) clusters have been investigated using high level ab initio quantum mechanical techniques with large basis sets. The highest level of theory employed in this study is TZ2P CCSD(T). The C₁ structure of H is predicted to be a global minimum, while the C_s structure of H is calculated to be a transition state. Harmonic vibrational frequencies are also determined at the DZP and TZ2P CCSD levels of theory. The dissociation energies, D_e, for H (n = 5–8) have been predicted using energy differences at each optimized geometry, and zero‐point vibrational energies (ZPVEs) are considered to compare with experimental values. The dissociation energies (D_o) have been predicted to be 1.69, 1.65, 1.65, and 1.46 kcal · mol for H, H, H (C₁ symmetry) and H, respectively, at the TZ2P CCSD(T) level of theory. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Variable-Temperature and Variable-Pressure Kinetic and Equilibrium studies of formation and dissociation of [V(H2O)5NCS]2+

The kinetics of formation and dissociation of [V(H₂O)₅NCS]²⁺ have been studied, as a function of excess metal-ion concentration, temperature, and pressure, by the stopped-flow technique. The thermodynamic stability of the complex was also determined spectrophotometrically. The kinetic and equilibrium data were submitted to a combined analysis. The rate constants and activation parameters for the formation (f) and dissociation (r) of the complex are: k/M ^?1 · S^?1 = 126.4, k/s^?1 = 0.82; ΔH /kJ · mol^?1 = 49.1, ΔH/kJ · mol^?1 = 60.6; ΔS/ J·K^?1·mol^?1= ?39.8, ΔSJ·K^?1·mol^?1 = ?43.4; ΔV/cm³·mol^?1 = ?9.4, and ΔV/cm³ · mol^?1 =?17.9. The equilibrium constant for the formation of the monoisothiocynato complex is K²⁹⁸/M ^?1 = 152.9, and the enthalpy and entropy of reaction are ΔH⁰/kJ · mol^?1 = ? 11.4 and ΔS⁰/J. K^?1mol^?1 = +3.6. The reaction volume is ΔV⁰/cm³· mol^?1 = +8.5. The activation parameters for the complex-formation step are similar to those for the water exchange on [V(H₂O)₆]³⁺ obtained previously by NMR techniques. The activation volumes for the two processes are consistent with an associative interchange, I_a, mechanism.     

Contribution à l'étude du système quaternaire K+?NH4+?CrO?SO?H2O: II. L'isotherme de 25°C

The study at 25°C of the system K⁺? NH? CrO? SO? H₂O has shown experimentally the existence of a new type of quaternary system of solubility with two cations and two anions. The solubility diagramm is caracterized by the presence of two adjacent ternary limiting systems with a miscibility gap, three univariant lines (one of them being evanescent), one invariant point, three binary and one ternary miscibility gaps.     

Exchange Equilibrium of Oxygen Isotopes between BrO,ClO, IO and Water

The liquid phase fractionation factors α_H = (¹⁸O/¹⁶O)_H2O/(¹⁸O/¹⁶O)xo and α_D = (¹⁸O/¹⁶O)_D2O/(¹⁸O/₁₆O)xo (X = Cl, Br, I) were calculated quantum mechanically between 0 and 100°. Experimental values were obtained in the case of BrO at 60° showing good agreement with the calculated results.     

Lithiumtriamidostannat(II), Li[Sn(NH2)3] – Synthese und Kristallstruktur

Lithium Triamidostannate(II), Li[Sn(NH₂)₃] – Synthesis and Crystal Structure Rusty-red glistening, transparent crystals of Li[Sn(NH₂)₃] were obtained by reaction of metallic lithium with tetraphenyl tin in liquid ammonia at 110 °C. The structure was determined from X-ray single-crystal diffractometer data: Space group P 2₁/n, Z = 4, a = 8.0419(9) Å, b = 7.1718(8) Å, c = 8.5085(7) Å, β = 90.763(8)°, R₁ (F _o ≥ 4σ(F _o)) = 2.8%, wR₂ (F ≥ 2σ(F )) = 5.3%, N(F ≥ 2σ(F )) = 1932, N(Var.) = 65. The crystal structure contains trigonal pyramidal complex anions [Sn(NH₂)₃]^– with tin at the apex, which are connected to layers of sequence A B A B … by lithium in tetrahedra-double units [Li(NH₂)_2/2(NH₂)₂]₂.     

Effects of nitrate and water on the oxygen isotopic analysis of barium sulfate precipitated from water samples

BaSO₄ precipitated from mixed salt solutions by common techniques for SO isotopic analysis may contain quantities of H₂O and NO that introduce errors in O isotope measurements. Experiments with synthetic solutions indicate that δ¹⁸O values of CO produced by decomposition of precipitated BaSO₄ in a carbon reactor may be either too low or too high, depending on the relative concentrations of SO and NO and the δ¹⁸O values of the H₂O, NO, and SO. Typical δ¹⁸O errors are of the order of 0.5 to 1‰ in many sample types, and can be larger in samples containing atmospheric NO, which can cause similar errors in δ¹⁷O and Δ¹⁷O. These errors can be reduced by (1) ion chromatographic separation of SO from NO, (2) increasing the salinity of the solutions before precipitating BaSO₄ to minimize incorporation of H₂O, (3) heating BaSO₄ under vacuum to remove H₂O, (4) preparing isotopic reference materials as aqueous samples to mimic the conditions of the samples, and (5) adjusting measured δ¹⁸O values based on amounts and isotopic compositions of coexisting H₂O and NO. These procedures are demonstrated for SO isotopic reference materials, synthetic solutions with isotopically known reagents, atmospheric deposition from Shenandoah National Park, Virginia, USA, and sulfate salt deposits from the Atacama Desert, Chile, and Mojave Desert, California, USA. These results have implications for the calibration and use of O isotope data in studies of SO sources and reaction mechanisms. Published in 2008 by John Wiley & Sons, Ltd.     

Crystal Structures of {[Cd(phen)](C6H8O4)3/3} and {[Cd(phen)](C7H10O4)3/3} · 2H2O with C6H10O4 = Adipic Acid and C7H12O4 = Pimelic Acid

Two coordination polymers {[Cd(phen)](C₆H₈O₄)_3/3} ( 1 ) and {[Cd(phen)](C₇H₁₀O₄)_3/3} · 2H₂O ( 2 ) were structurally characterized by single crystal X‐ray diffraction methods. In 1 (C2/c (no. 15), a = 16.169(2)Å, b = 15.485(2)Å, c = 14.044(2)Å, β = 112.701(8)°, U = 3243.9(7)ų, Z = 8), the Cd atoms are coordinated by two N atoms of one phen ligand and five O atoms of three adipato ligands to form mono‐capped trigonal prisms with d(Cd‐O) = 2.271‐2.583Å and d(Cd‐N) = 2.309, 2.390Å. The [Cd(phen)] moieties are bridged by adipato ligands to generate {[Cd(phen)](C₆H₈O₄)_3/3} chains, which, via interchain π—π stacking interactions, are assembled into layers. Complex 2 (P1¯(no. 2), a = 9.986(1)Å, b = 10.230(3)Å, c = 11.243(1)Å, α = 66.06(1)°, β = 87.20(1)°, γ = 66.71(1)°, U = 955.7(2)ų, Z = 2) consists of {[Cd(phen)](C₇H₁₀O₄)_3/3} chains and hydrogen bonded H₂O molecules. The Cd atoms are pentagonal bipyramidally coordinated by two N atoms of one phen ligand and five O atoms of three pimelato ligands with d(Cd‐O) = 2.213—2.721Å and d(Cd‐N) = 2.329, 2.372Å. Through interchain π—π stacking interactions, the {[Cd(phen)](C₇H₁₀O₄)_3/3} chains resulting from [Cd(phen)] moieties bridged by pimelato ligands are assembled in to layers, between which the hydrogen bonded H₂O molecules are sandwiched.     

63Cu-NMR.-Untersuchungen von Kupfer (I)-Tetrapyridin-und Kupfer (I)-Tetraacetonitrilsolvaten

⁶³Cu-NMR.-Spectra of Cu(CH₃CN)₄X (X = ClO, BF, PF) and Cu(C₅H₅N)₄X (X = ClO, BF) in solution are reported at different temperatures and concentrations. The influence of temperature on the linewidth and chemical shift indicates an equilibrium of Cu(CH₃CN) and Cu(C₅H₅N) with another complex of lower symmetry. The preferential solvation of Cu (I) by pyridin in a mixture acetonitrile/pyridine is clearly shown.     

Gas-phase chemistry of the methyl carbamate radical cation,H2NCOOCH. II—A test case for ion structure assignment

The unimolecular chemistry of the methyl carbamate radical cation, H₂NCOOCH, 1, has been further investigated by a combination of mass spectrometry-based experiments (metastable ion (MI), collisional activation (CA), collision-induced dissociative ionization (CIDI), neutralization-reionization (NR) Spectrometry and ²H labelling) and ab initio molecular orbital calculations, executed at the MP3/6–31G*//4–31G level of theory and corrected for zero-point vibrational energies. Apart from the previously located maxima, i.e. H₂NCOOCH₃^+·, 1, the distonic ion H₂NC(OH)OCH₃^+·, 2, hydrogen-bridged ions [H₂N? C?O…? H…?O?CH₂]^+·, 5, and [H₂N? CH?O…?…?H…?O?C? H]^+·, 7, there exist at least two other equilibrium structures, viz. the iminol ion H? N?C(OH)? OCH, la, and the hydrogen-bridged species [H₂C?O…?H…?N(H)COH], 6a, which is closely related to ion 5. Although the iminol ion la lies only 30 kJ mol^?1 above 1, our calculations indicate that the barriers for its formation either directly from ionized methyl carbamate 1 via a 1,3-hydrogen shift or indirectly via 1,4-hydrogen shifts from the distonic ion 2 are too high to allow the iminol ion to be involved in the unimolecular chemistry of ionized methyl carbamate. This explains the earlier observation that there are no H-D exchange reactions prior to decomposition of ionized labelled methyl carbamate, in contrast to the related ion methyl acetate. However, attempts to generate the iminol ion by loss of CH₃CN from CH₃CH?N? NHCOOCH₃ produced the more stable distonic ion 2 instead, but it proved very difficult to assign its structure unequivocally because 2 can rapidly interconvert with 1 and so virtually identical dissociation characteristics ensue. Only by integration of results obtained from many experiments and from ab initio calculations could structure 2 be assigned. The distonic ion 2 can undergo two transformations: after stretching of the C? OCH₂ bond the incipient formaldehyde can migrate within the electrostatic field of ionized hydroxyaminocarbene to the OH end to generate 5, but it can also migrate to the NH end to generate 6a. This explains the previous puzzling observation that H₂NCOOCD forms both CD₂OD^· and CD₂OH^· in CA and NR experiments. The calculations and experiments indicate that, although the ion is exceedingly difficult to characterize, the distonic ion 2 is the key intermediate for all the observed dissociations of methyl carbamate.