Reactions of [Co₂(µ-HOCHRCCCHROH)(µ-dppm)(CO)₄](R = H or Me, dppm = Ph₂PCH₂PPh₂) with HO(CH₂)_nOH (n= 4–6) in the presence of HBF₄·OEt₂ afforded the Co₂(µ-dppm)(CO)₄-complexed tetraoxacyclodiynes [(OC)₄(µ-dppm)Co₂{µ-CCHRO(CH₂)_n OCHRC}₂Co₂(µ-dppm)(CO)₄]. The dimeric nature of the products was confirmed by fast atom bombardment mass spectroscopy and the crystal structure of [(OC)₄(µ-dppm)Co₂{µ-CCH₂O(CH₂)₄OCH₂C}₂Co(µ-dppm)(CO)₄]. The acid-catalysed reaction of [Co₂(µ-HOCH₂CCCH₂OH)(µ-dppm)(CO)₄] with triethylene glycol and a NaBF₄ template afforded [Co₂{µ-CCH₂O[(CH₂)₂O]₃CH₂C}(µ-dppm)(CO)₄] which can co-ordinate Li⁺. The analogous reaction with tetraethylene glycol afforded [Co₂Na{µ-CCH₂O[(CH₂)₂O]₄CH₂C}(µ-dppm)(CO)₄]BF₄, in which the sodium template remains co-ordinated by the crown ether. Washing with deionised water removes the Na⁺ ion to produce [Co₂{µ-CCH₂O[(CH₂)₂O]₄CH₂C}(µ-dppm)(CO)₄] which forms complexes with LiBF₄ and KSCN.