Abstract A series of linear, five-donor-atom compounds, with nitrogen, sulphur, and oxygen donor-atoms, has been prepared to examine the effects of steric crowding on the formation of octahedral complexes. 1, 11-Diamino-3, 9-dithia-6-azaundecane (5) and 4-methyl-1, 7-di (8?-quinolyl)-1, 7-dithia-4-azaheptane (6) form octahedral complexes with Ni (ClO 4) 2 or Co (ClO 4) 2. An increase in the bulkiness of the ligand, as shown by 1, 11-bis ( ...