First Isolation and Spectroscopic Observation of Thiofulminic acid (HCNS)

Abstract

For the first time: Thiofulminic acid (HCNS), the parent member of the nitrile sulfide family of reactive intermediates and potential interstellar species, was produced and characterized by IR spectroscopy for the first time. HCNS was generated in cryogenic matrices by 254 nm UV irradiation of 1,2,5‐thiadiazole (see figure).

Generation and Spectroscopic Identification of Selenofulminic Acid and Its Methyl and Cyano Derivatives (XCNSe, X=H, CH3, NC)

“…A promising method for spectroscopic detection seems to be the generation of nitrile selenides in cold, inert noble gas matrices, in which thermal decomposition and bimolecular reactions are avoided. This is in line with the relevant nitrile sulfide chemistry, for which all of the four spectroscopically identified derivatives, HCNS, [9] FCNS, [10] CH 3 CNS, [11,12] and PhCNS, [12,13] have been identified at low temperatures and in inert matrices. Possible sources of nitrile selenides could be molecules containing the CNSe linkage and a good leaving group, releasing the desired product upon UV irradiation.…”

“…Notably, the frequency of the CH mode of HCNS [9] and HCNSe is lower by 15 and 17 cm À1 , respectively, than that of HCN. As can be expected, the CN stretching mode is much more affected by the NS and NSe bond formation.…”

“…As can be expected, the CN stretching mode is much more affected by the NS and NSe bond formation. Compared with HCN the CN stretching mode is shifted by À58 and À48 cm À1 in HCNS [9] and HCNSe, respectively. In addition to the CH and CN stretching fundamentals the NSe stretching is also observed at 504, 500, and 496 cm…”

“…Generation and identification of HCNSe: Based on our previous results on nitrile sulfides [9][10][11] the narrow-band UV photolysis of 1,2,5-selanadiazole seemed to be an appropriate generation route of HCNSe. HCN is an ideal side product in the sense that it has only very low-intensity IR bands in the CN stretching region (see Table S4 in the Supporting Information) and does not absorb in the investigated UV region.…”

“…Possible sources of nitrile selenides could be molecules containing the CNSe linkage and a good leaving group, releasing the desired product upon UV irradiation. We have successfully applied 1,2,5-thiadiazoles as sources of nitrile sulfides recently, [9][10][11] thus 1,2,5-selenadiazoles have been selected for the present study as potential sources of nitrile selenides. It is important to note that PhCNSe was generated analogously from 3,4-diphenyl-1,2,5-selenadiazole and 3,5-diphenyl-1,2,4-selenadiazole earlier.…”