Characterization of new sulfide ions (C2S3 center dot+) from ethenedithione by ion-molecule reactions

Collisional activation thigh or low translational energy) and neutralizatio n-reionization mass spectrometries appear inefficient for the characterizat ion of the connectivity of isomeric C2S3.+ ions generated by dissociative i onization of 1,2-dithiolo[4,3-c] [1,2]dithiole-3,6-dione (1), 1,2-dithiolo[ 4,3-c] [1,2]dithiole-3-one-6-thione (2), and 1,3,4,6-tetrapentalene-2,5-dio ne (3). In contrast, ion-molecule reactions (particularly with nitric oxide ) readily differentiate the C-sulfide ethenedithione ion, SCCS2.+ (4), and the S-sulfide ethenedithione ion, SCCSS.+ (5). The collisional activation s pectra of these ion-molecule reaction products have been recorded on a new type of hybrid tandem mass spectrometer of sectors-quadrupole-sectors confi guration. The characterization of the isomeric C2S3.+ ions is supported by ab initio calculations at the G2(MP2,SVP) level. The C-sulfide ethenedithio ne ion is predicted to be more stable than the S-sulfide form by 91 kJ mol( -1). The calculated reaction enthalpies for the two isomeric forms C2S3.+ W ith nitric oxide support the characterization by ion-molecule reactions.