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.     

Mass-selected molecular ion spectra: (1+1)-Photodissociation spectroscopy of CH3I+ and CD3I+

The first well resolved (1+1)-photodissociation spectra of molecular ions are presented. By separating the spectroscopic step (first photon) and the dissociation step (second photon) we could extend the accessible spectral region of CH₃I⁺ and CD₃I⁺ considerably. The ions are prepared in the vibrationless ground state by MPI in a supersonic molecular beam. A new detection technique is presented with high discrimination between wanted and unwanted ionic species. Furthermore, another new technique for unimolecular decay measurements delivers useful information for the assignment of the ion spectra. We found an improved assignment for CH₃I⁺ and CD₃I⁺ with consequences for molecular constants.     

N-Methyl-N-diäthoxyphosphorylamido-Derivate des Hexachlorocyclotriphosphazatriens. IV. NMR-spektroskopische Untersuchungen zur Konstitution der Ammonolyseprodukte von N-Methyl-N-diäthoxyphosphorylamido-chloro-cyclotriphosphazatrienen

N-Methyl-N-Diethoxyphosphorylamido Derivatives of Hexachlorocyclotriphosphazatriens. IV N.M.R. Spectroscopic Investigations of the Products of the Ammonolysis of N-methyl-N-diethoxyphosphorylamindo-chloro-cyclotriphosphazatrienes Broad band ¹H decoupled ³¹P n.m.r. spectra of products obtained by ammonolysis of N-methyl-N-diethoxyphosphorylamido-chloro-cyclotriphosphazatrienes provide essential hints at the constitution of these compounds. In this connection it may be easily demonstrated, both amino groups of N₃P₃Cl₃[NCH₃P(O)(OC₂H₅)₂][NH₂]₂ as well as of N₃P₃Cl₂[NCH₃P(O)(OC₂H₅)₂]₂ [NH₂]₂ are arranged geminally. The spectral parameters were found and verified by simulation of spectra. The simulated ³¹P spectra agree closely with the observed ones. The conclusions from the ³¹P n.m.r. spectra are complemented by these from the ¹H n.m.r. spectra.     

A combined experimental and theoretical study of resonance emission spectra of SO2( B2)

Experimental and theoretical resonance emission spectra are obtained for a number of vibrational states of SO₂( ¹B₂). The experimental emission spectra are dominated by (n₁ν₁, n₂ν₂, 0) bands, but some weak activity in the anti-symmetric stretch (ν₃) is observed. The calculated emission spectra based on an empirical near-equilibrium potential energy surface agree reasonably well with experiment for two lowest states investigated here, but fail to reproduce higher ones. Resonance Raman spectra are also calculated and agree well with an earlier experiment.     

1H-Festkörper-NMR-Untersuchungen am synthetischen Pektolith Ca2NaHSi3O9

Solid-state ¹H N.M.R. Studies of Synthetic Pectolite Ca₂NaHSi₃O₉ A synthetic pectolite Ca₂NaHSi₃O₉ is studied by means of conventional ¹H pulse-fourier-transform wide line n.m.r. and methods of solid-state high-resolution ¹H n.m.r. (MREV8 multiple pulse technique, combined multiple pulse magic angle spinning experiments). The n.m.r. spectra consist of a dominant signal due to SiOH groups and a small signal which can be assigned to water molecules. The parameters of the ¹H n.m.r. spectra for the SiOH groups are discussed in comparison with the known structure of pectolite. It can be shown that the structural details for the proton of the SiOH groups are reflected by the ¹H n.m.r. spectra.     

The electronic spectra of 10, 10-dimethylanthracen-9-one crystals: Spin—orbit/vibronic coupling in 3nπ3 states

10, 10-dimethylanthracen-9-one single crystal emission and absorption spectra have been recorded at low temperatures, as well as Raman spectra on the melt. The absorption spectra of both the lowest triplet and lowest excited singlet states clearly show the absorption origins of the three different molecular sites in the triclinic unit cell of the crystal. The emission spectra indicate that substantial spin—orbit/vibronic state mixing occurs, giving rise to transitions between the z sub-level of the lowest ³nπ³ state (T₁) and both totally and non-totally symmetric vibrations of the ground state. The preferred intensity stealing route is from T₁ (z) to S₂(¹ππ³) by spin—orbit coupling with vibronic mixing of S₃ and S₄(¹ππ³, ¹B₂).     

Über Chalkogenolate. 96 [1]. Untersuchungen über Alkalimetalltrimethylsilylcarbonate

On Chalcogenolates. 96. Studies on Trimethylsilyl Carbonates of Alkali Metals The trimethylsilyl carbonates M[O₂COSi(CH₃)₃] with M = Li, Na, K, Rb, Cs have been prepared by reaction of Co₂ with the corresponding silanolate. Infrared spectra, electron absorption spectra, ¹H-NMR spectra as well as mass spectra are communicated. In aqueous solution the equivalent conductivities of [O₂COSi(CH₃)₃]^? have been determined by means of conductivity measurements. The diffusion coefficient of the ion was calculated. The dissociation constant of trimethylsilyl carbonic acid in water at 20°C is K_a = (4,83 ± 0,5) · 10^?10. The thermodynamic data of the dissociation were calculated.     

The evolution of inner-shell multielectronic X-ray spectra from threshold to saturation for low- to high-Z atoms

Inter- and intra-shell electronic correlations in an atom are manifested in, and can be studied through, the X-ray emission spectra of multielectronic transitions. We have measured the spectra of K^hα_1,2 hypersatellites (HS), Kα_3,4 satellites (S), and the 3d electron shake-up satellites (D) accompanying the Kα_1,2 diagram lines, and their evolution from the double-ionization threshold, for selected 4- and 5-row elements of the periodic table. These spectra originate in the [1 s]⁻¹, [2p]⁻¹, and [3d]⁻¹ spectator two-electron transitions [1 s]⁻²→[1s2p]⁻¹, [1s2p]⁻¹→[2p]⁻², and [1s3d]⁻¹→[2p3d]⁻¹ respectively. Photoexcitation by monochromatized synchrotron radiation together with high-resolution crystal spectrometers were employed. Ab initio relativistic multiconfigurational Dirac–Fock (RMCDF) calculations reproduce the spectra very well for all transitions, with the HS spectra showing a strong dependence on QED effects. The excitation thresholds were determined accurately. The threshold-to-saturation energy range of the intensity was found to depend strongly on the principal quantum number n of the spectator hole. For example, for Cu, ranges of 2%, 10%, and 60% of the threshold energy are found for the D, S and HS spectra, respectively. Only the D spectrum's evolution conforms to the Thomas model, indicating a dominant shake up/off process. The S and HS spectra seem to be dominated by the knockout (“two-step-one”) process near threshold. The S spectra show a two-regime behavior. Near threshold both shape and intensity vary with excitation energy, and above that only intensity changes are observed. The lower-than-expected K^hα₁/K^hα₂ intensity ratio found for Z=23–30 and 39–46 indicates that the angular momenta coupling scheme at the regime intermediate between the LS coupling at low-Z and the jj coupling at high-Z may not be fully accounted for by the prevailing theory.     

Infrared and Raman spectra and normal coordinate calculations for methylisothiocyanate

The infrared spectra (3200-50 cm^?1) of gaseous and solid CH₃NCS and CD₃NCS and the Raman spectra (3200-10 cm^?1) of the liquids and solids have been recorded. The spectra have been interpreted on the basis of a “pseudo-symmetric top” with C_3v symmetry. An assignment of the fundamental vibrations in both molecules, based on their infrared band contours, depolarization values and group frequencies, is given and discussed. Particularly interesting is the low-frequency region where band maxima were observed at 152 and 80 cm^?1 for CH₃NCS and 139 and 71 cm^?1 for CD₃NCS in the infrared spectra of the gases. A normal coordinate analysis has also been carried out based on C_3v symmetry. Considerable mixing was found between the C_αN stretch and NCS symmetric stretch in both isotopic species. The other normal modes in CH₃NCS are reasonably pure but, for the CD₃NCS molecule, considerable mixing was found between the CD₃ stretches and NCS antisymmetric stretch. The proposed vibrational assignment and the results of the normal coordinate calculations are discussed and compared with the results obtained for similar molecules.     

Analysis of organic salts by laser ionization mass spectrometry. Sulfonates,sulfates and thiosulfates

Sodium and potassium salts of organic sulfonates (1-decyl, 1-dodecyl and 1-hexadecyl), sulfates (1-hexyl, 1-decyl and 1-octadecyl) and thiosulfates (1-octyl, 1-dodecyl, 1-tetradecyl, 1-hexadecyl, benzyl and β-phenylethyl) were ionized by laser irradiation and the positive ions were analyzed by time-of-flight mass spectrometry. The organic ions observed were always intense and due to the molecular species plus a cation or a dimer plus a cation. The spectra of the thioslufates and sulfates show an abundance of inorganic ions in contrast to the sulfonates. The thiosulfate spectra are characterized by intense [Na₃SO₃]⁺ or [K₃SO₃]⁺ ions and the sulfates by intense [Na₃SO₄]⁺ or [K₃SO₄]⁺ ions.     

Synthesis and characterization of a new pillar[5]arene-based [1]rotaxane

In this study, we reported the synthesis of three kinds of mono-functional pillar[5]arene derivatives PRI, PRII and R and their structures were studied by 1D and 2D NMR spectra and mass spectra. The 2D NMR spectra including ¹H-¹³C HSQC, ¹H-¹H COSY and NOESY spectra indicated that PRI and PRII are both stable self-included pseudo[1]rotaxanes in CDCl₃. These original structures are promising compounds for the design of pillar[5]-based [1]rotaxane. And the results showed that R could exist stable in CDCl₃ and DMSO because of the coordination of N-H?O hydrogen bonding interaction and C-H?π interaction.     

High-resolution NMR spectra of fluorene and its derivatives: VI—1-methylfluorene,truxene and decacyclene

The overlapping spin systems in the 220 MHz ¹H spectra of 1-methylfluorene (1) in carbon disulphide and deuteriated chloroform solutions have been analysed separately and refined by LAOCOON with the aid of methyl- and methylene-decoupled spectra. Ortho-coupling constants in the 6-membered rings are similar to each other and to those in fluorene (4). Solvent and concentration shifts suggest loose pairing of solute molecules. 220 MHz ¹H spectra of α-truxene (2) in carbon tetrachloride and deuteriated nitrobenzene, 220 MHz ¹H spectra of decacyclene (3) in carbon tetrachloride, and 90 MHz FT ¹H spectra of 3 in deuteriated chloroform show steric deshielding; the solvent dependence of shifts also suggests solute pairing in 2. Shifts in ¹H decoupled 22.6 MHz ¹³C spectra of 2 in deuteriated chloroform were assigned with the aid of Cr(acac)₃ relaxation agent.     

Raman spectra of gases: XIV. Hexachlorodisiloxane

The Raman spectra (50–1200 cm^?1) of gaseous, liquid, and solid (Cl₃Si)₂O have been recorded. The infrared spectra of the gas and solid have been recorded from 55–2000 cm^?1 . The spectra of the gas have been interpreted in detail on the basis of C_2v symmetry with the A₁ skeletal Si-O-Si bend assigned at 63 cm^?1. The spectra gave evidence that there are structural changes upon condensation of the gas and the Si-O-Si angle approaches linearity in the solid state. The opening of this angle is probably due to crystal packing factors.     

ESR spectra and magnetic constants of α-Al2O3:Co2+,H+ and α-Al2O3 :Co2+,X+

New anisotropic ESR spectra of Co²⁺ doped sapphire, different from hitherto known, are reported. The new spectra which are observed, beside the well-known spectra of α-Al₂O₃:Co²⁺, are shown to form two sets, each one consisting of six spectra (1–6) and (7–12). The spectra of both sets are proven to be interrelated by B_3a symmetry. g and A tensors for each set will be given. Evidence is given that the two sets are to be assigned to the defects α-Al₂O₃:Co²⁺,H⁺ and α-Al₂O₃:Co²⁺,X⁺. The former is concluded to consists of a Co²⁺ ion at the substitutional site (c) and a proton located in a potential minimum along a straight line between O^2- ions situated in O²⁺ triangles above and below the CO²⁺ ion. The potential function for the proton has been calculated by quantum-chemical calculations to clucidate the geometrical structure of the paramagnetic center. The α-Al₂O₃:Co²⁺,X⁺ could not be fully analyzed but some evidence is presented, that X⁺ might be alkali ions.     

Darstellung und Charakterisierung der Pentammin-Komplexe [Os(NH3)5(NCS)]2+ und [Os(NH3)5(NCSe)]2+

Preparation and Characterization of the Pentammine Complexes [Os(NH₃)₅(NCS)]²⁺ and [Os(NH₃)₅(NCSe)]²⁺ The new pentammine complexes [Os(NH₃)₅(NCS)]²⁺ and [Os(NH₃)₅(NCSe)]²⁺ are prepared from the reaction of [Os(NH₃)₅(CF₃SO₃)](CF₃ SO₃)₂ with NH₄SCN and KSeCN, respectively, in acetone, and subsequent purification by ion exchange chromatography on carboxymethyl cellulose. Evidence of N-bonding in both cases is given by the vibrational spectra, indicating that Os³⁺ is in terms of Lewis acidity harder than Ru³⁺, Rh³⁺, and Ir³⁺. I.r. and Raman spectra are interpreted according to local C_4v symmetry around Os, and the presumed assignments are confirmed by comparison with the i.r. spectra of the perdeuterated compounds. In the electronic spectra of both complexes charge transfer bands at 412 nm (NCS) and 498 nm (NCSe) are observed, respectively. Further weak absorptions near 4500 and 5100 cm^?1, which are in correlation with electronic Raman bands, are assigned to intraconfigurational transitions within the ²T_2g (O_h) ground term, split into three Kramers doubletts by spin-orbit coupling and lowered symmetry. Electrochemical measurements demonstrate a stabilisation of +III and +II oxidation states by π-back donation to —NCS and —NCSe ligands.     

Vibrational spectra and structure of gaseous and solid dimethylboric anhydride

The Raman spectra of gaseous, liquid and solid dimethylboric anhydride (CH₃)₂BOB(CH₃)₂ have been recorded from 10–3500 cm^?1. The IR spectra from 4000–30 cm^?1 have also been recorded. The spectra of the gaseous phase have been interpreted in terms of C₂ symmetry implying a bent B-O-B skeleton with the B(CH₃)₂ groups twisted and consistent with a rather larger barrier to internal rotation about the B-O bonds. The spectra of the crystalline state, however, suggest that the molecular symmetry is altered upon solidification. Isotopic substitution of the oxygen atom by ¹⁸O confirmed that the B-O-B skeleton is linear in the solid state, and the spectra have been interpreted in terms of D_2h molecular symmetry.     

Hexamminmetall(III)-hexachlorochromate(III): Darstellung,Kristallgitter und Spektren

Hexammine-metal(III) hexachlorochromates(III). Preparation, crystal lattic and spectra The preparation of [Me(NH₃)₆]CrCl₆ with Me = Co and Rh from aqueous solutions and with Me = Co, Cr and Rh by thermal dehydratation is given. The crystal structure of these compounds is T_h⁶? Pa3, Z = 4. The absorption spectrum shows the two known spin allowed bands at 13300 and 1890C cm^?1. Some weak vibronic absorptions are observed from 13870 cm^?1 to 15130 cm^?1. The vibrational spectrum of CrCl₆^2? has been completed by the measurement of the RAMAN spectrum, the IR spectra have been reinvestigated. The vibrational spectra confirm the nearly undisturbed octahedral symmetry of the hexahalogenometallate anion which has previously been observed for similar compounds.     

Darstellung und Charakterisierung von Phthalocyanin-π-Kation-Radikalen von H+, Mg2+ und Cu2+

Preparation und Characterization of Phthalocyanine-π-Cation-Radicals of H⁺, Mg²⁺, and Cu²⁺ The preparation of phthalocyanine-π-cation-radicals (Pc(?1)) of H⁺, Mg²⁺, Cu²⁺ is described. MgClPc(?1) and Cu(NO₃)Pc(?1) · HNO₃ are isolated as stoichiometrically pure, stable redbrown solids. Contrary to the phthalocyanines(?2) (Pc(?2)) these are very soluble with redviolet colour in organic solvents in the presence of R? COOH (R ? H, CF₃, CCl₃). The electronic absorption absorption spectra (UV-VIS) are remarkably solvent-dependent. This solvent effect is due to a reversible radical association. Monomeric radical species exist in nonpolar (CH₂Cl₂), dimeric in polar solvents (CH₃NO₂, C₂H₅OH). The UV-VIS, infrared (IR), and resonance-raman (RR) spectra of MgClPc(?1) and Cu(NO₃)Pc(?1) · HNO₃ are discussed and compared with the analogoues spectra of MgPc(?2) · 2 H₂O and MgPc(?2) · HCl. Although there are only minor differences in the chemical composition and the electronic structure the spectroscopic data vary significantly for every complex. Especially the IR spectrum is suitable for a quick demonstration of the π-cation-radicals. The diagnostic bands are at ca. 1350 and 1450 cm^?1.     

Préparation,sites de symétrie et photoluminescence de l'ion Bi3+ dans les antimoniates de terres rares Y2BSbO7 (B = Ga,Lu, Y)

New rare-earth antimonates Y₂BSbO₇(B = Ga, Lu, Y) have been prepared. Excitation and emission spectra of these host lattices doped with Eu³⁺ reveal two symmetry sites for Eu³⁺ (Y and B sites). The symmetry of these sites is not D_3d as in the pyrochlore structure.The photoluminescence of the Bi³⁺ ion is analysed in these compounds. The spectra are ascribed to the ³¹S₀ → ³P₁ and ³P₁ → ¹S₀ transitions with a perturbation due to the ³P₀ metastable level. The decay curve consists of two exponentials in agreement with the presence of Bi³⁺ in two symmetry sites.     

Solid state NMR studies of syndiotactic polystyrene/ethylbenzene and poly(ethylene oxide)/LiCF3SO3 molecular complexes

Solvent dynamics and polymer-solvent interactions in syndiotactic (s) polystyrene (PS)/ethylbenzene (PhEt) clathrates, as well as polymer-salt interactions in the poly(ethylene oxide) (PEO)/LiCF₃SO₃ complex, were characterized by solid state ¹H and ¹³C NMR. ¹H static and ¹H MAS NMR spectra have shown that PhEt molecules in s-PS clathrates retain relatively large, but spatially anisotropic mobility. ¹³C CP/MAS (cross polarization/magic angle spinning) spectra and CP dynamics measured for s-PS-dg/PhEt system indicate that at least a part of PhEt molecules are intercalated between phenyl rings of s-PS. ¹³C CP/MAS NMR spectra show that PEO carbons in complex with LiCF₃SO₃ are more shielded in comparison to neat crystalline PEO. The results (distances) obtained from CP dynamics are in agreement with the published crystal structure of the PEO/LiCF₃SO₃ complex. ¹³C spin-lattice relaxation time measurements have shown that the mobility of PEO in the complex is lower than that in neat crystalline PEO.