Synthesis of Hexacarbonyldicobalt-Complexed Thiacycloalkynes

Reaction of [Co2(mu-HOCR1R2C=CCR1R2OH)(CO)6] (R1 = R 2 = 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(mu-HOCH2C=CCH2OH)(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(mu-CCH2SCH2CH2SCH2C)(mu-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, H-1 and C-13 NMR spectra of the new compounds are discussed.