Cyclooligomerization of 1-ethynylazulenes 1a,b, 6 and 7 as well as 1,2-bis(azulen-1-yl)ethynes 10a,b and 11 with CpCo(CO)₂ to the corresponding 1,2,4-tris(azulen-1-yl)benzenes 14a,b, 18 and 19 as well as [bis- and tetrakis(azulen-1-yl)cyclobutadiene]cobalt complexes 17a,b, 30a,b and 31 is described
