Synthesis of hexacarbonyldicobalt-complexed thiacycloalkynes

Abstract

Reaction of [Co₂(µ-HOCR¹R²CCCR¹R²OH)(CO)₆](R¹= R²= H or Me; R¹= H, R²= Me) with HS(CH₂)_nSH (n= 2–5) or HS(CH₂)₂OH in the presence of HBF₄·OEt₂ affords predominately monomeric hexacarbonyldicobalt-complexed thiacycloalkynes. In many cases, especially with the longer chain dithiols, dimeric compounds are also formed as minor products and in some cases higher oligomers have also been characterised. Reaction of [Co₂(µ-HOCH₂CCCH₂OH)(CO)₆] with HSCH₂CH(OH)CH₂SH affords complexed thiacycloalkynes with pendant hydroxyl functionalities. The monomeric complexes undergo carbonyl substitution with bis(diphenylphosphino)methane (dppm) and the X-ray crystal structure of [Co₂(µ-CCH₂SCH₂CH₂SCH₂C)(µ-dppm)(CO)₄] has been determined. The molecule contains a co-ordinated 1,4-dithiacyclooct-6-yne which adopts two conformations in the solid state. The IR, mass, ¹H and ¹³C NMR spectra of the new compounds are discussed.