Novel route to iron-carbene derivatives via addition of alkynes to carbon disulfide-iron complexes. Rearrangement of (1,3-dithiol-2-ylidene)iron complexes into heterometallacycles

Article abstract of DOI:10.1021/ic50222a024

Addition of a variety of alkynes, containing a formyl, acyl, or carboxylate group, to a benzene solution of Fe(η²-CS₂)-(CO)₂[P(OMe)₃] ₂ produces carbene-iron complexes (A), the (1,3-dithiol-2-ylidene)iron derivatives 2 resulting from the bonding of both sulfur atoms to the alkyne carbons. The reaction of dimethyl acetylenedicarboxylate with Fe(η²-CS₂)(CO)₂L₂ affords the carbene complex A which is stable when L is P(OMe)₃ or PPh₃ but isomerizes into a heterometallacycle (B) for L = PMe₃ and gives the A ? B equilibrium when L = PMe₂Ph. The cycloaddition of the alkyne to the CS₂ ligand is shown to be reversible. The A ? B equilibrium constant and the rate of the isomerization of A increase with the electron-donating capability of the ligand L. 1,3-Dipolar cycloaddition of the alkyne to the FeCS₂ moiety may account for these reactions.