Mono‐ and Bicyclic Organometallic Ring Systems with Exocyclic CC and CS Bonds

The cobaltaheterocycles [C 5 H 5 Co{κ 2 (C,S)‐C(=CH 2 )‐N(R)C(=S)S](PMe 2 Ph)] ( 5‐7 ), which contain both an exocyclic CC and CS bond, were prepared from the iminoacylcobalt compounds [C 5 H 5 Co(C(CH 3 )=NCH} (PMe 2 Ph)]I ( 2‐4 ) on treatment with either CS 2 /NaOCH 3 or K[S 2 CNMe 2 ], respectively. While protonation of 5 (R = CH 3 ) and 7 (R = CH 2 Ph) with HBF 4 occurs at the exocyclic CCH 2 bond to give cations containing a CoC(CH 3 )N(R)C(=S)S ring, the methylation of 5 and 7 with [OMe 3 ]BF 4 takes place at the exocyclic CS bond and generates five‐membered heterocycles heterocycles with an SCH 4 substituent. The reaction of 5‐7 with S 8 leads to the elimination of the phosphane ligand and affords the bicyclic dithiolenecobalt complexes 14 ‐ 16 in moderate to good yields. On treatment of 5 ‐ 7 with C 2 (CO 2 R′)2 (R′ = Me,Et), an insertion of the alkyne into the CCH 2 bond occurs and five‐membered ring systems 19 ‐ 22 with an unsaturated exocyclic =C(CO 2 R′)‐C(CO 2 R′)=CH 2 group are formed. As in the case of 5 and 7 , protonation and methylation reactions of 19 also take place at different sites leading to cations with either a delocalized CoCN or NCS unit.