Electronic Properties and Dissociative Photoionization of Thiocyanates, Part III. The Effect of the Group’s Electronegativity in the Valence and Shallow-Core (Sulfur and Chlorine 2p) Regions of CCl₃SCN and CCl₂FSCN

Abstract

Both photoelectron spectroscopy (PES) data and PhotoElectron-PhotoIon-Coincidence (PEPICO) spectra obtained from a synchrotron facility have been used to examine the electronic structure and the dissociative ionization of halomethyl thiocyantes in the valence and shallow-core S 2p and Cl 2p regions. Two simple and closely related molecules, namely, CClSCN and CClFSCN, have been analyzed to assess the role of halogen substitution in the electronic properties of thiocyanates. The assignment of the He(I) photoelectron spectra has been achieved with the help of quantum chemical calculations at the outer-valence Green's function (OVGF) level of approximation. The first ionization energies observed at 10.55 and 10.78 eV for CClSCN and CClFSCN, respectively, are assigned to ionization processes from the sulfur lone pair orbital [n(S)]. When these molecules are compared with CXSCN (X = H, Cl, F) species, a linear relationship between the vertical first ionization energy and electronegativity of CX group is observed. Irradiation of CClSCN and CClFSCN with photons in the valence energy regions leads to the formation of CClX and CClXSCN ions (X = Cl or F). Additionally, the achievement of the fragmentation patterns and the total ion yield spectra obtained from the PEPICO data in the S 2p and Cl 2p regions and several dissociation channels can be inferred for the core-excited species by using the triple coincidence PEPIPICO (PhotoElectron-PhotoIon-PhotoIon-Coincidence) spectra.

Simple Disulfides: Studies of Some Exponents of a Family Involved in Prominent Processes

“…Thus, the non‐bonded electron pair at the sulfur atom attached to the “acceptor” group CCl 3 presents higher ionization energy with ionization energies varying in a much more limited range. This general behavior was also studied for a series of −SCN containing molecules [42] …”

Spectroscopic and structural studies on phenyl and pentafluorophenyl trifluorothioacetate, and pentafluorophenyl trifluoroacetate, CF3C(O)SC6H5, CF3C(O)SC6F5 and CF3C(O)OC6F5

“…1 For this, a range of techniques and spectroscopies were used from vibrational spectroscopy to the application of techniques associated with high-energy phenomena associated with the use of synchrotron facilities. 2 The amalgamation of these studies allows obtaining information on the behavior of these species in a wide range of the electromagnetic spectrum. Phenomena of photo-evolution, rotamerization, formation of new molecules, possibly of interstellar species, could be approached given the systematization of experiments, determinations and properties shared for these families of compounds.…”

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

“…Thus, the determination of photevolution mechanisms in a wide energy range became possible together with the detection of the involved intermediates. 20,21 Here we present the results of a photolysis study of PFPA using a wide range of synchrotron radiation extending from VUV to X-Ray in the electromagnetic spectrum.…”

“…Thus, the determination of photoevolution mechanisms in a wide energy range became possible together with detection of the involved intermediates. 20,21 Here we present the results of a photolysis study of PFPA using a wide range of synchrotron radiation extending from the VUV to X-ray in the electromagnetic spectrum. Valence (11.7−21.4 eV) and inner shell (278.0−750.0 eV) energies were investigated, as were the total ion yield (TIY), photoelectron−photoion coincidence (PEPICO), and photoelectron−photoion−photoion coincidence (PEPIPICO) spectra, in order to follow both excitation and ionization processes.…”

“…Our research group has been involved for many years in photochemical studies of very simple species, using both nonionizing and ionizing radiation. Thus, the determination of photoevolution mechanisms in a wide energy range became possible together with detection of the involved intermediates. , …”