Production and IR Absorption of Cyclic CS₂ in Solid Ar

Abstract

Linear carbon disulfide (denoted as SCS) isolated in solid N 2 or Ar at 13 K was irradiated with light at 193 nm from an ArF excimer laser. In addition to an absorption line of CS at 1277.4 cm -1 , new lines at 881.3 and 520.9 cm -1 were observed after photolysis of SCS in solid N 2 . These lines are assigned to cyclic CS 2 (denoted cyc-CS 2 ) based on results from 34 S-and 13 C-isotopic experiments. Doublet lines of cyc-CS 2 at 876.5 (881.1) and 517.7 (522.7) cm -1 were observed after irradiation of SCS in solid Ar at 193 nm; lines in parentheses are associated with a minor matrix site. Secondary photolysis at 248, 308, 532, 560, or 580 nm diminishes signals of cyc-CS 2 and produces SCS. Theoretical calculations using MP2-full and density-functional methods (BLYP and B3LYP) predict three isomers of CS 2 : SCS, cyc-CS 2 , and linear CSS; relative energies, structures, vibrational wavenumbers, and IR intensities were predicted for each isomer. Cyc-CS 2 has C-S bonds (∼1.74 Å) elongated relative to those of SCS (∼1.56 Å), a S-S bond ∼2.14 Å, and ∠SCS ≈ 76°; it lies ∼73 kcal mol -1 above SCS. Calculated vibrational wavenumbers, IR intensities, and isotopic shifts for cyc-CS 2 fit satisfactorily with experimental results. An asymmetric transition state connecting SCS and cyc-CS 2 is characterized, yielding a ring-opening barrier of ∼24.4 kcal mol -1 (zero-point energy corrected). Photoconversion between linear and cyclic CS 2 in a matrix cage is discussed.

Photochemistry of OPN: Formation of Cyclic PON and Reversible Combination with Carbon Monoxide

“…Indeed, it was observed in the photo‐induced isomerization between SPN and SNP . Another two experimentally established 16‐electron triatomic rings are cyclic CS 2 ( 9 , matrix‐isolation IR spectroscopy) and cyclic SiS 2 ( 10 , microwave spectroscopy) . According to the Walsh rules, the 16‐electron triatomic rings consisting of at least two first‐row elements, such as cyclic N 2 O, N 2 S, CO 2 , and SiO 2 should be even less stable and synthetically more difficult.…”

Isomers of NCO2: IR-absorption spectra of ONCO in solid Ne

“…7 The branching ratio for the highly exothermic channel ͑1c͒ has been determined as ͑22± 2͒%, 3 ͑23± 10͒%, 8 and ͑29± 2͒%. 7 Utilizing selective photodissociation with a laser to avoid secondary photolysis of species of interest, [11][12][13][14] we produced numerous novel species by either photolysis of a precursor in situ [15][16][17][18][19][20] or by further reactions of photofragments with a nearest neighbor upon photolysis; 21-24 these species are difficult to produce in the gaseous phase using conventional techniques. Quantum-chemical calculations that reaction ͑1c͒ proceeds via formation of NCOO, 7 followed by isomerization to ONCO via a barrier of ϳ236 kJ mol −1 , then dissociation to CO and NO via a barrier of ϳ14 kJ mol −1 .…”

Isomers of SNO2: Production and infrared spectra of cis- and trans-OSNO from irradiated inert matrices containing OCS and NO2

“…[9][10][11][12][13][14][15][16][17] From such experiments we report here infrared spectral identification of cis-and trans-OSNO, to be designated as c-OSNO and t-OSNO hereafter, in laser-irradiated matrices containing OCS and NO 2 , and with quantum-chemical calculations of possible isomers of SNO 2 . [9][10][11][12][13][14][15][16][17] From such experiments we report here infrared spectral identification of cis-and trans-OSNO, to be designated as c-OSNO and t-OSNO hereafter, in laser-irradiated matrices containing OCS and NO 2 , and with quantum-chemical calculations of possible isomers of SNO 2 .…”

“…A predicted splitting of16 OSN 18 O and 18 OSN 18 O for N-O stretching mode of c-OSNO is greater than for t-OSNO, and an observed splitting for set ''c'' is greater than for set ''t'' ͑Table III͒. ͑1͒ Predicted wave numbers of S-O stretching mode for t-OSNO exceed by ϳ20 cm Ϫ1 that for c-OSNO, and the observed value is 22 cm Ϫ1 greater for set ''t''.…”