Twisted Imide Bond in Noncyclic Imides. Synthesis and Structural and Vibrational Properties of <i>N</i>,<i>N</i>-Bis(furan-2-carbonyl)-4-chloroaniline

A novel imide compound (C₁₆H₁₀ClNO₄) was synthesized in a single step by the reaction of 2-furoic acid with 4-chloroaniline in a 2:1 molar ratio using carbonyldiimidazole (CDI) in dry THF. The structure was supported by spectroscopic and elemental analyses and the single-crystal X-ray diffraction data. Crystallographic studies revealed that the compound crystallized in a monoclinic system with space group <i>P</i>2₁/<i>c</i> and unit cell dimensions <i>a</i> = 12.2575(5) Å, <i>b</i> = 7.7596(2) Å, <i>c</i> = 15.0234(7) Å, α = γ = 90°, β = 92.771(4)°, <i>V</i> = 1427.25(10) ų, <i>Z</i> = 4. The imide bond is twisted, and the OC–N–C­(O) units deviate significantly from planarity with dihedral angles around the imide group reaching ca. −150.3° (C1–N1–C2–O21 = −148.8° and C2–N1–C1–O11 = −151.9°). The nonplanarity of the imide moiety and the related conformational properties are discussed in a combined approach that includes the analysis of the vibrational spectra together with theoretical calculation methods, especially in terms of natural bond orbital (NBO) calculations

Conformational Properties of Ethyl- and 2,2,2-Trifluoroethyl Thionitrites, (CX₃CH₂SNO, X = H and F)

The simple 2,2,2-trifluoroethyl thionitrite molecule, CF₃CH₂SNO, has been prepared in good yield for the first time using CF₃CH₂SH and NOCl in slight excess. The vapor pressure of the red-brown compound CF₃CH₂SNO follows, in the temperature range between 226 and 268 K, the equation log <i>p</i> = 12.0–3881/<i>T</i> (<i>p</i>/bar, <i>T</i>/K), and its extrapolated boiling point reaches 51 °C. Its structural and conformational properties have been compared with the ethyl thionitrite analogue, CH₃CH₂SNO. The FTIR spectra of the vapor of both thionitrites show the presence of bands with well-defined contours, allowing for a detailed conformational analysis and vibrational assignment on the basis of a normal coordinate analysis. The conformational space of both thionitrite derivatives has also been studied by using the DFT and MP2­(full) level of theory with extended basis sets [6-311+G­(2df) and cc-pVTZ]. The overall evaluation of the experimental and theoretical results suggests the existence of a mixture of two conformers at room temperature. The relative abundance of the most stable syn form (NO double bond syn with respect to the C–S single bond) has been estimated to be ca. 79 and 75% for CF₃CH₂SNO and CH₃CH₂SNO, respectively

Matrix Isolation Study of the Conformations and Photochemistry of S‑Ethyl Fluorothioformate, FC(O)SCH₂CH₃

The IR spectra of S-ethyl fluorothioformate, FC­(O)­SCH₂CH₃, were recorded in the vapor phase and compared with the Raman spectrum in the liquid state. Additional IR spectra of the compound isolated in argon and nitrogen matrices at ca. 12 K were also recorded. The title compound exhibits rich conformational equilibria at room temperature being <i>C</i>₁ the most stable symmetry with a synperiplanar orientation of the carbonyl double bond (CO) with respect to the S–C­(sp³) single bond, while the C–C bond of the ethyl group presents a gauche orientation with respect to the C–S single bond. Several bands assigned to a second conformer were also observed in the IR matrix spectra. This second rotamer presents a planar skeleton (<i>C</i>_<i>s</i> point group) retaining the prevalent syn orientation of the FC­(O)­SCH₂CH₃ molecule with an antiperiplanar orientation of the C–C bond of the ethyl group with respect to the C–S bond. The variation of the nozzle temperature before matrix gas deposition gives rise to different conformer ratios. With these data an enthalpy difference of 0.45 kcal mol^–1 can be calculated between the more stable <i>C</i>₁ and the <i>C</i>_<i>s</i> conformers. A third form, corresponding to the anti-gauche conformer, is also detected when the matrix is exposed to broad-band UV–visible irradiation. Moreover, the photochemistry of the Ar and N₂ matrix-isolated species is studied. Conformational interconversion is observed at short irradiation times, whereas a decarbonylation process with the concomitant formation of a HC­(S)­CH₃:HF molecular complex dominates the photochemistry of FC­(O)­SCH₂CH₃ of longer irradiation times. The new ethyl fluoro sulfide, FSCH₂CH₃, is proposed as an intermediate species

Valence and Inner Electronic Excitation, Ionization, and Fragmentation of Perfluoropropionic Acid

The photoexcitation, photoionization, and photofragmentation of gaseous CF₃CF₂C­(O)­OH were studied by means of synchrotron radiation in the valence and inner energy regions. Photofragmentation events were detected from 11.7 eV through formation of COH⁺, C₂F₄⁺, and the parent species M⁺. Because the vertical ionization potential has been reported at 11.94 eV, the starting energy used in this study, 11.7 eV, falls just inside of the tail of the ionization band in the photoelectron spectra. Information from the total ion yield spectra around the C 1s, O 1s, and F 1s ionization potentials allows the energies at which different resonance transitions take place in the molecule to be determined. These transitions have been assigned by comparison with the results of the analysis of similar compounds. In the inner energy region, both kinetic energy release (KER) values and the slope and shape of double coincidence islands obtained from photoelectron–photoion–photoion coincidence (PEPIPICO) spectra allow different photofragmentation mechanisms to be elucidated

Photoexcitation, Photoionization, and Photofragmentantion of CF₃CF₂CF₂C(O)Cl Using Synchrotron Radiation between 13 and 720 eV

The main inner shell ionization edges of gaseous CF₃CF₂CF₂C­(O)­Cl, including Cl 2p, C 1s, O 1s, and F 1s, have been measured in Total Ion Yield (TIY) mode by using tunable synchrotron radiation, and several resonance transitions have been assigned with the help of quantum chemical calculations. Interestingly, resonance transitions observed in the C 1s region can be assigned to different carbon atoms in the molecule according to the degree of fluorine substitution. Ionic photofragmentation processes have been studied by time-of-flight mass spectrometry in the Photoelectron-Photoion-Coincidence (PEPICO) and Photoelectron-Photoion-Photoion-Coincidence (PEPIPICO) modes. These techniques revealed a “memory-lost” effect especially around the C 1s region, since the fragmentation events are independent of the energy range considered. Moreover, different fragmentation mechanisms were inferred from these spectra in the valence (13.0–21.0 eV) as well as in the inner (180.0–750.0 eV) electronic energy regions. The vibrational spectral features of CF₃CF₂CF₂C­(O)Cl have been interpreted in terms of a conformational equilibrium between two conformations (<i>gauche</i> and <i>anti</i> of the CC single bond with respect to the CCl one) at room temperature, as determined from quantum chemical calculations and the detailed analysis of the infrared spectrum

Electronic Properties of Fluorosulfonyl Isocyanate, FSO₂NCO: A Photoelectron Spectroscopy and Synchrotron Photoionization Study

The electronic properties of fluorosulfonyl isocyanate, FSO₂NCO, were investigated by means of photoelectron spectroscopy and synchrotron based techniques. The first ionization potential occurs at 12.3 eV and was attributed to the ejection of electrons formally located at the π NCO molecular orbital (MO), with a contribution from nonbonding orbitals at the oxygen atoms of the SO₂ group. The proposed interpretation of the photoelectron spectrum is consistent with related molecules reported previously and also with the prediction of OVGF (outer valence green function) and P3 (partial third order) calculations. The energy of the inner- and core–shell electrons was determined using X-ray absorption, measuring the total ion yield spectra, and the resonances before each ionization threshold were interpreted in terms of transitions to vacant molecular orbitals. The ionic fragmentation mechanisms in the valence energy region were studied using time-of-flight mass spectrometry as a function of the energy of the incident radiation. At 13 eV the M⁺ was the only ion detected in the photoion–photoelectron–coincidence spectrum, while the FSO₂⁺ fragment, formed through the breaking of the S–N single bond, appears as the most intense fragment for energies higher than 15 eV. The photoion–photoion–photoelectron–coincidence spectra, taken at the inner- and core-levels energy regions, revealed several different fragmentation pathways, being the most important ones secondary decay after deferred charge separation mechanisms leading to the formation of the O⁺/S⁺ and C⁺/O⁺ pairs

Electronic Properties of FC(O)SCH₂CH₃. A Combined Helium(I) Photoelectron Spectroscopy and Synchrotron Radiation Study

The valence electronic properties of <i>S</i>-ethyl flouromethanethioate (<i>S</i>-ethyl fluoromethsanethioate), FC­(O)­SCH₂CH₃, were investigated by means of He­(I) photoelectron spectroscopy in conjunction with the analysis of the photofragmentation products determined by PEPICO (phtoelectron-photoion-coincidence) by using synchrotron radiation in the 11.1–21.6 eV photon energy range. The first band observed at 10.28 eV in the HeI photoelectron spectrum can be assigned with confidence to the ionization process from the HOMO [n_π(S) orbital], which is described as a lone pair formally localized on the sulfur atom, in agreement with quantum chemical calculations using the outer valence Green function method [OVGF/6-311++G (d,p)]. One of the most important fragmentation channels also observed in the valence region corresponds to the decarbonylation process yielding the [M–CO]^·+ ion, which is clearly observed at <i>m</i>/<i>z</i> = 80. Moreover, S 2p and S 2s absorption edges have been examined by measuring the total ion yield spectra in the 160–240 eV region using variable synchrotron radiation. The dynamic of ionic fragmentation following the Auger electronic decay has been evaluated with the help of the PEPIPICO (photoion–photoion–photoelectron–coincidence spectra) technique

Electronic Properties and Dissociative Photoionization of Thiocyanates. Part II. Valence and Shallow-Core (Sulfur and Chlorine 2p) Regions of Chloromethyl Thiocyanate, CH₂ClSCN

A combination of photoelectron spectroscopy and synchrotron based photoelectron photoion coincidence (PEPICO) spectra has been applied to investigate the electronic structure and the dissociative ionization of the CH₂ClSCN molecule in the valence region. The PES is assigned with the electronic structure calculations at the outer-valence Green’s function and symmetry adapted cluster/configuration interaction (SAC-CI) levels offer an explanation of our experimental results. Upon vacuum ultraviolet irradiation the low-lying radical cation, located at 10.39 eV is formed. The molecular ion is observed in the time-of-flight mass spectra, together with the CH₂SCN⁺ and CH₂Cl⁺ daughter ions. The total ion yield spectra have been measured in the S 2p and Cl 2p regions and several channels have been determined in dissociative photoionization events for the core-excited species. Thus, by using time-of-flight mass spectrometry and synchrotron radiation the relative abundances of the ionic fragments and their kinetic energy release values were obtained from both PEPICO and photoelectron photoion photoion coincidence spectra. Possible fragmentation processes are discussed and compared with that found for the related CH₃SCN species

Supplementary Material for: Thrombolysis for acute wake-up and unclear onset strokes with alteplase at 0.6 mg/kg in clinical practice: THAWS2 Study

Introduction: The aim of this study was to determine the safety and efficacy of intravenous (IV) alteplase at 0.6 mg/kg for patients with acute wake-up or unclear onset strokes in clinical practice. Methods: This multicenter observational study enrolled acute ischemic stroke patients with last-known-well time >4.5 h who had mismatch between DWI and FLAIR and were treated with IV alteplase. The safety outcomes were symptomatic intracranial hemorrhage (sICH) after thrombolysis, all-cause deaths and all adverse events. The efficacy outcomes were favorable outcome defined as an mRS score of 0–1 or recovery to the same mRS score as the premorbid score, complete independence defined as an mRS score of 0–1 at 90 days, and change in NIHSS at 24 h from baseline. Results: Sixty-six patients (35 females; mean age, 74±11 years; premorbid complete independence, 54 [82%]; median NIHSS on admission, 11) were enrolled at 15 hospitals. Two patients (3%) had sICH. Median NIHSS changed from 11 (IQR, 6.75–16.25) at baseline to 5 (3–12.25) at 24 h after alteplase initiation (change, –4.8±8.1). At discharge, 31 patients (47%) had favorable outcome and 29 (44%) had complete independence. None died within 90 days. Twenty-three (35%) also underwent mechanical thrombectomy (no sICH, NIHSS change of –8.5±7.3), of whom 11 (48%) were completely independent at discharge. Conclusions: In real-world clinical practice, IV alteplase for unclear onset stroke patients with DWI-FLAIR mismatch provided safe and efficacious outcomes comparable to those in previous trials. Additional mechanical thrombectomy was performed safely in them