Addition of CHSiMe3 to the Co-S Bond of 1,2,5,3-cobaltadithiazole. Formation and reactions of stereoisomeric cobaltathiirane complexes

Article abstract of DOI:10.1016/0022-328X(95)05386-4

In the reaction between (η⁵-cyclopentadienyl)(1-phenylmethanimine-N,1-dithiolato)cobalt(III), , 1) and trimethylsilyldiazomethane, trimethylsilylmethylene adds between Co and S adjacent to N.Two geometrical isomers of cobaltathiirane complexes are formed: in the major addition product 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.Equilibrium is attained in 10 h at 80 deg C, when the reaction is started either from 2a or from 2b.Form the temperature dependence of the equilibrium, ΔG value of the isomerization of the stereoisomers is estimated to be 34 kJ mol^-1.These isomeric trimethylsilylmethylene adducts react with HCl to give a common product, chloro(η⁵-cyclopentadienyl)cobalt(III) (4).By treatment with tetrabutylammonium fluoride, 4 undergoes a ring reforming reaction to give a methylene adduct, (η⁵-cyclopentadienyl)-1-phenylmethanimine-1-thiolato-κS>cobalt(III).Keywords: Cobalt; Thiirane; Cobaltadithiazole; Isomerization; Addition-elimination; Alkylidene