Isomers of OCS2: IR absorption spectra of OSCS and O(CS2) in solid Ar

Abstract

Irradiation of an Ar matrix sample containing O(3) and CS(2) with a KrF excimer laser at 248 nm yielded new lines at 1402.1 (1404.7), 1056.2 (1052.7), and 622.3 (620.5) cm(-1); numbers in parentheses correspond to species in a minor matrix site. Secondary photolysis at 308 nm diminished these lines and produced mainly OCS and SO(2). Annealing of this matrix to 30 K yielded a second set of new lines at 1824.7 and 617.8 cm(-1). The first set of lines are assigned to C=S stretching, O-S stretching, and S-C stretching modes of carbon disulfide S-oxide, OSCS; and the second set of lines are assigned to C=O stretching and OCS bending modes of dithiiranone, O(CS(2)), respectively, based on results of (34)S- and (18)O-isotopic experiments and quantum-chemical calculations. These calculations using density-functional theory (B3LYP/aug-cc-pVTZ) predict four stable isomers of OCS(2): O(CS(2)), SSCO, OSCS, and SOCS, listed in order of increasing energy. According to calculations, O(CS(2)) has a cyclic CS(2) moiety and is the most stable isomer of OCS(2). OSCS is planar, with bond angles angle OSC congruent with 111.9 degrees and angle SCS congruent with 177.3 degrees ; it is less stable than SSCO and O(CS(2)) by approximately 102 and 154 kJ mol(-1), respectively, and more stable than SOCS by approximately 26 kJ mol(-1). Calculated vibrational wave numbers, IR intensities, (34)S- and (18)O-isotopic shifts for OSCS and O(CS(2)) fit satisfactorily with experimental results.

Electron Irradiation of Carbon Disulfide-Oxygen Ices: Toward the Formation of Sulfur-Bearing Molecules in Interstellar Ices

“…The ν 1 fundamental mode of carbon monoxide (CO) was detected at 2139 cm −1 (Bennett et al 2004). The formation of carbonyl sulfide (OCS) was confirmed via the detection of ν 1 fundamental at 2039 cm −1 ; this data is in close agreement with the literature value of 2049 cm −1 (Garozzo et al 2010;Lo et al 2004). The doublets at 1399 cm −1 and 1388 cm −1 were identified as the ν 3 fundamental of sulfur trioxide (SO 3 ) and its dimer (SO 3 :SO 3 ) (Garozzo et al 2010;Lo et al 2004), respectively.…”

“…The formation of carbonyl sulfide (OCS) was confirmed via the detection of ν 1 fundamental at 2039 cm −1 ; this data is in close agreement with the literature value of 2049 cm −1 (Garozzo et al 2010;Lo et al 2004). The doublets at 1399 cm −1 and 1388 cm −1 were identified as the ν 3 fundamental of sulfur trioxide (SO 3 ) and its dimer (SO 3 :SO 3 ) (Garozzo et al 2010;Lo et al 2004), respectively. Absorption of the sulfur dioxide (SO 2 ) fundamentals were probed at 1335 cm −1 (ν 3 ), 1148 cm −1 (ν 1 ), and 528 cm −1 (ν 2 ) with excellent correlation with literature values at 1337 cm −1 , 1150 cm −1 , and 520 cm −1 , respectively (Garozzo et al 2010;Lo et al 2004).…”

“…The doublets at 1399 cm −1 and 1388 cm −1 were identified as the ν 3 fundamental of sulfur trioxide (SO 3 ) and its dimer (SO 3 :SO 3 ) (Garozzo et al 2010;Lo et al 2004), respectively. Absorption of the sulfur dioxide (SO 2 ) fundamentals were probed at 1335 cm −1 (ν 3 ), 1148 cm −1 (ν 1 ), and 528 cm −1 (ν 2 ) with excellent correlation with literature values at 1337 cm −1 , 1150 cm −1 , and 520 cm −1 , respectively (Garozzo et al 2010;Lo et al 2004). The ν 3 fundamental of ozone (O 3 ) was detected at 1040 cm −1 (Bennett et al 2004;Garozzo et al 2010).…”

“…The infrared spectroscopic investigations revealed the formations of OCS, SO 2 , and SO 3 as major products with minor amounts of CO. Similar experiments were performed while probing the reaction of CS 2 with atomic oxygen (O) at ∼13 K (Lo et al 2004); these studies revealed the formation of carbonyl sulfide (OCS), sulfur dioxide (SO 2 ), and sulfur trioxide (SO 3 ) along with carbon monosulfide (CS) and sulfur monoxide (SO). The reaction of CS 2 with atomic oxygen (O) was also investigated in the gas phase.…”

Formation of Interstellar OCS: Radiation Chemistry and IR Spectra of Precursor Ices

“…In contrast, the intermediate dithiiranone, OCS 2 , grew in and then decayed with continued irradiation, as indicated by the feature at 1807 cm À1 . Its identification is based on matrix spectra of Lo et al (2004). Observation of this and other intermediates identified earlier was helpful in elucidating possible reaction mechanisms for the solid-state processes observed.…”