EPR studies on the thiophenodithiazolyl radical, C4H2S3N˙?

Dalton Transactions Pub Date: 2005-10-05 DOI: 10.1039/B508912C

Abstract

Selective chlorination of thiophene-2,3-dithiol with SO2Cl2 generates the corresponding sulfenyl chloride, 2,3-C4H2S(SCl)2. Subsequent condensation with Me3SiN3 yields the thiophenodithiazolylium salt [C4H2S3N]Cl, [TDTA]Cl. The structure of the cation, TDTA+, was established by X-ray diffraction as both its AsF6? and HSO4? salts. Reduction of [TDTA]Cl with Ag powder yields the radical TDTA˙ which was characterised by X- and Q-band (9 and 34 GHz) EPR and ENDOR studies. The spin density distributions estimated from the EPR/ENDOR measurements were found to be in very good agreement with those determined by DFT (B3LYP/6-31G*) indicating that ca 10% of the spin density is delocalised onto the thiophene ring. Comparison of the spin density distributions in TDTA˙ and the isoelectronic trithiatriazapentalenyl radical C2S3N3, TTTA˙, indicates that replacement of N by C–H leads to a localisation of the spin density on the dithiazolyl ring.

Graphical abstract: EPR studies on the thiophenodithiazolyl radical, C4H2S3N˙
Recommended Literature