1.2- Dithiolenes 5-dealkylation

In contrast to arenedithiols, 1,2-alkenedithiols are usually unstable. The corresponding alkenedithiolate dianions are, however, valuable precursors to dithiolene complexes, although they vary widely in their ease of manipulation. Salts of the required ds-[C2R2S212 can be generated by the reductive cleavage of cis-1,2-bis(benzylthio)alkenes using Na/NH3 (few alkali metal salts of dithiolenes have in fact been characterized in any detail). The reductive dealkylation was discussed above as a route to benzene- and thiophenedithiolates (15, 43, 44). 

Whereas complexes of ethylenedithiolate H2C2S212 are typically prepared by the reductive S-dealkylation of c -H2C2(SCH2Ph)2 (Section II.B), a viable alternative route involves base hydrolysis of l,3-dithiol-2-one, H2C2S2(CO).The parent H2C2S2CO can in turn be prepared on a multigram scale from chloroacetal-dehyde (82). This l,3-dithiol-2-one can be functionalized via deprotonation followed by C-alkylation (72), thus opening the way to a variety of functional dithiolenes (Eq. 7). 

Complexes of alkyl-linked o-benzenedithiolates eliminate ethylene to give benzenedithiolato complexes (Eq. 27) (275-277). This reaction is the reverse of the known addition of alkenes to bis(dithiolene) complexes (278-281). Photolysis of the S-benzylated dithiolenes M(PhCH2S2C2Ph2)2 (M = Ni, Pd, Pt) results in S-dealkylation with elimination of benzyl radicals (282). In general, however, the properties of S-alkylated dithiolenes have not been... 

All three members of the electron transfer chain [Mo(CO)2(S2C2Me2)]" (n = 0,1, 2) were isolated and characterized. The complexes have trigonal prismatic geometries, and structural, spectral, and electrochemical properties that are consistent with the redox orbital having predominantly sulfur-ligand based character (>80%) behavior consistent also with DFT calculations. Closely related benzene- and 2,4-di-i-butyl-benzene-dithiolene complexes, [Mo(LL )(bdt)2] (L = 0, L = PPha, L = L = PMeR2 (R = Me or Ph)) were obtained by thioether S-dealkylation of appropriate dttd (22) complexes of molybdenum carbonyls and oxo species. 

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