The first example of a complex containing a C₁₉ chain, {Co₃(μ-dppm)(CO)₇}{μ₃-C(C≡C)₉}{W(CO)₃Cp}, has been prepared in 22% yield from the Pd(0) / Cu(I)-catalysed reaction between I(C≡C)₃I, W{C≡CC≡CAu(PPh₃)}(CO)₃Cp and Co₃{μ₃-C(C≡C)₄Au(PPh₃)}(μ-dppm)(CO)₇. Other products also formed include {Co₃(μ-dppm)(CO)₇}{μ₃-C(C≡C)₆}{W(CO)₃Cp} (32%), {Co₃(μ-dppm)(CO)₇}₂{μ₃:μ₃-C(C≡C)xC} [x = 8 (6%) and 11 (5%)], containing respectively C₁₃, C₁₈ and C₂₄ chains, and {W(CO)₃Cp}₂{μ-(C≡C)x} (x = 4, 7) (traces). A second example of a 19-atom chain is found in Hg{(C≡C)₄C[Co₃(μ-dppm)(CO)₇]}₂, obtained in 24% yield from the reaction between Hg(OAc)₂ and Co₃{μ₃-C(C≡C)₄SiMe₃}(μ-dppm)(CO)₇ in the presence of NaOMe.