ADDITION OF CHSIME(3) TO THE CO-S BOND OF 1,2,5,3-COBALTADITHIAZOLE -FORMATION AND REACTIONS OF STEREOISOMERIC COBALTATHIIRANE COMPLEXES

In the reaction between yl(1-phenylmethanimine-N,1-dithiolato)cobalt(I II), ([CpCoSNC(Ph)S](n) 1) and trimethylsilyldiazomethane, trimethylsi lylmethylene adds between Co and S adjacent to N. Two geometrical isom ers of cobaltathiirane complexes are formed: in the major addition pro duct 2a, the trimethylsilyl group is located at the anti-position with respect to the cobaltadithiazole ring and in the minor product 2b, at the syn-position. These two stereoisomers are in equilibrium. Equilib rium is attained in 10 h at 80 degrees C, when the reaction is started either from 2a or from 2b. From the temperature dependence of the equ ilibrium, de value of the isomerization of the stereoisomers is estima ted to be 34 kJ mol(-1). These isomeric trimethylsilylmethylene adduct s react with HCl to give a common product, chloro(eta clopentadienyl)[ N-(trimethylsilylmethylthio)-kappa S-1-phenylmethanimine-1-thiolato-ka ppa S]cobalt(III) (4). By treatment with tetrabutylammonium fluoride, 4 undergoes a ring reforming reaction to give a methylene adduct, (eta (5)-cyclopentadienyl)[N-(methylene-kappa C)-thio-kappa S]-1-phenylmeth animine-1-thiolato-kappa S]cobalt(III).