EQUILIBRIUM STUDIES OF COPPER(II) AND OF NICKEL(II) COMPLEXES WITH SULFIDE CONTAINING ALPHA,OMEGA-DIAMINES

The complex formation of Cu2+ and Ni2+ with 1,7-diaza-4-thiaheptane (2,2-NSN), l,8-diaza-4-thiaoctane (2,3-NSN), l,9-diaza-4-thianonane (2,4-NSN) and l,9-diaza-5-thianonane (3,3-NSN) has been studied potentiometrically at 25°C in 0.5 mol dn-3 (K)NO3medium. The formation constants of the CuL2+ complexes with the four ligands are 9.02, 10.03, 9.49 and 9.79 respectively. In these 1:1 complexes the ligands can be facially disposed. 2,2-NSN and 2,3-NSN also form a CuL22+complex with log K2 = 5.24 and 2.86 respectively, whereas the hydrolysis constants of the [Cu(OH)L]+species with the same ligands are 5.90 and 4.60. 2,3-NSN also forms the species CuHL3+ and CuHL23+, with protonation constants 4.77 and 9.7 respectively. With Ni2+only 5,5- and 5,6-membered chelate ring systems are formed. With 2,2-NSN log K1 = 7.377 and log K2 = 6.142. With 2,3-NSN log K1 = 5.989 and log K2 = 3.86. There is a six co-ordinate environment about the metal ion in the NiL22+complexes. The Ni(II) complexes of the latter ligand may be protonated to NiHL3+ and NiHL23+with protonation constants of 6.9 and 8.2 respectively. © 1979, Taylor & Francis Group, LLC. All rights reserved.