Structure and stability of small nitrile sulfides and their attempted generation from 1,2,5-thiadiazoles

T. Pasinszki, T. Kárpáti, Nicholas P C Westwood

Research output: Contribution to journalArticle

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Abstract

The gas-phase generation and spectroscopic identification of nitrile sulfides by thermolysis of 1,2,5-thiadiazole precursors was attempted, but in all cases the thiadiazoles were found to produce sulfur and the corresponding nitrile. This prompted an investigation by ab initio and density functional calculations for the equilibrium geometries, stabilities, and decomposition mechanisms of several nitrile sulfides (XCNS, where X = H, F, Cl, CN, CH3). Equilibrium geometries obtained from calculations at the B3LYP, MPn(n = 2-4), QCISD, QCISD(T), CCSD, and CCSD(T) levels with moderate to large basis sets indicate that the molecules have linear heavy atom geometries. The exception is the fluoro derivative, which is bent with a calculated barrier to linearity of 889 cm-1 (B3LYP/cc-pVTZ). The nitrile sulfides are predicted by the B3LYP method to be stable in the dilute gas phase, whereas in the condensed phase they are suggested to be very unstable due to bimolecular decomposition. The mechanism of this loss process is complicated by various sulfur transfer and cyclization reactions between decomposition intermediates, with the predicted stable products being sulfur, nitriles, and thiadiazoles. The first step of the bimolecular decomposition is either a cycloaddition to thiofuroxan or a sulfur transfer with simultaneous S2 loss to nitriles.

Original languageEnglish
Pages (from-to)6258-6265
Number of pages8
JournalJournal of Physical Chemistry A
Volume105
Issue number25
DOIs
Publication statusPublished - Jun 28 2001

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Thiadiazoles
Nitriles
nitriles
Sulfides
sulfides
Sulfur
sulfur
Decomposition
decomposition
Geometry
geometry
Gases
vapor phases
Thermolysis
Cycloaddition
Cyclization
cycloaddition
Density functional theory
linearity
Derivatives

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Structure and stability of small nitrile sulfides and their attempted generation from 1,2,5-thiadiazoles. / Pasinszki, T.; Kárpáti, T.; Westwood, Nicholas P C.

In: Journal of Physical Chemistry A, Vol. 105, No. 25, 28.06.2001, p. 6258-6265.

Research output: Contribution to journalArticle

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