The first example of a complex containing a C 19 chain, {Co 3 (μ-dppm)(CO) 7 }{μ 3 -C(C≡C) 9 }{W(CO) 3 Cp}, has been prepared in 22% yield from the Pd(0) / Cu(I)-catalysed reaction between I(C≡C) 3 I, W{C≡CC≡CAu(PPh 3 )}(CO) 3 Cp and Co 3 {μ 3 -C(C≡C) 4 Au(PPh 3 )}(μ-dppm)(CO) 7 . Other products also formed include {Co 3 (μ-dppm)(CO) 7 }{μ 3 -C(C≡C) 6 }{W(CO) 3 Cp} (32%), {Co 3 (μ-dppm)(CO) 7 } 2 {μ 3 :μ 3 -C(C≡C) x C} [x=8 (6%) and 11 (5%)], containing respectively C 13 , C 18 and C 24 chains, and {W(CO) 3 Cp} 2 {μ-(C≡C) x } (x=4, 7) (traces). A second example of a 19-atom chain is found in Hg{(C≡C) 4 C[Co 3 (μ-dppm)(CO) 7 ]} 2 , obtained in 24% yield from the reaction between Hg(OAc) 2 and Co 3 {μ 3 -C(C≡C) 4 SiMe 3 }(μ-dppm)(CO) 7 in the presence of NaOMe.