Velocity-Map Imaging and Magnetic-Bottle Photoelectron Spectroscopy of [SeCCH]⁻: Electronic Properties and Spin–Orbit Splitting

Abstract

The recently synthesized acetylide compound KSeCCH containing the main group element selenium within the novel and in crystalline form unprecedented [SeCCH]− anion was successfully investigated in the gas phase by high-resolution velocity-map imaging (VMI) and magnetic-bottle (MB) photoelectron spectroscopy coupled with an electrospray ionization source. Both VMI and MB spectra exhibited identical electron affinities (EA, 2.517 ± 0.002 eV), spin–orbit coupling (SOC) splittings (1492 ± 20 cm–1), and Se–C stretching frequencies (573 ± 20 cm–1) of the corresponding neutral tetra-atomic radical [SeCCH]• with the VMI spectrum possessing six times higher spectral resolution compared with the MB spectrum. These experimental values were well reproduced by calculations at the CCSD­(T) level, in which both the isolated [SeCCH]− anion and the [SeCCH]• radical adopted linear geometries. The simulated spectra based on the calculated Franck–Condon factors, the SOC splitting, and the experimental line width matched well with the measured spectra. Furthermore, comparisons of the EA and SOC splitting values with the previously reported isolobal species [SeCN]• are also made and discussed. The decrease in the EA and SOC splitting of [SeCCH]• is ascribed to the differences in the electronegativities between C and N atoms as well as the electron density on the Se atom in its singly occupied molecular orbital (SOMO).

Li2[SeC2Se]·2NH3: A Crystalline Ammoniate with a –Se–C≡C–Se– Dianion

“…In 2018, we reported the synthesis and structural characterization of A I SeC 2 H with A I = K, Rb, Cs, which were accessible by reactions of A I C 2 H with elemental selenium, either its red or gray polymorph, in liquid ammonia . The existence of the – SeC 2 H anion for the first time in a stable crystalline material was remarkable, although the anion or its radical had already been the subject of several theoretical , or gas phase investigations , and was also postulated as an intermediate in selenoorganic reactions. , Furthermore, some organic compounds with the general composition HC 2 Se-R (R = benzyl or alkyl) have been reported. , In upcoming work, we could show that the [SeCCH] − anion of KSeC 2 H can be transferred to the gas phase by electron spray methods, where its neutral tetra-atomic radical [SeCCH] • was thoroughly characterized by high-resolution velocity-map imaging (VMI) and magnetic-bottle (MB) photoelectron spectroscopy . In 2020, we added the synthesis and structural characterization of NaSeC 2 H 11 to this new class of compounds.…”

“…8,9 In upcoming work, we could show that the [SeCCH] − anion of KSeC 2 H can be transferred to the gas phase by electron spray methods, where its neutral tetra-atomic radical [SeCCH] • was thoroughly characterized by high-resolution velocity-map imaging (VMI) and magnetic-bottle (MB) photoelectron spectroscopy. 10 In 2020, we added the synthesis and structural characterization of NaSeC 2 H 11 to this new class of compounds. Surprisingly, a disordered [SeCCH] − anion was found in the latter with a pyrite-type structure.…”