1079-1083Copper (I) perchlorate solutions of different concentrations in acetonitrile have been conductometerically titrated with solutions of thiourea (TU), N,N-dimethylthiourea (DMTU), N-phenylthiourea (NPTU), N, N-diphenylthioarea (DPTU), 1,10-phenanthroline (PHEN), 2,2' -bipyridyl (BPY) and triethylphosphite (TEP) at 298 K. The plots of conductivity versus moles of ligand added show significant decrease in conductivity followed by a region of almost constant conductivity. The fall of conductivity in the cases of thiourea and substituted thioureas is linear while in all the other cases it is non-linear. From these plots knowledge about the stoichiometry of the complexes formed between copper (I) perchlorate and various ligands has been derived. A complex of stoichiometry 1:2 is observed between copper (I) perchlorate and 1, 10-phenanthroline and 2, 2' -bipyridyl and 1:4 complex with triethylphosphite. Copper (I) perchlorate, however, forms complexes with thiourea and substituted thioureas, the stoichiometry of which strongly depends upon the concentrations of copper (I) perchlorate as well as of the ligands used for the titration. With N-phenylthiourea and N,N-diphenylthiourea, the complex formed has copper (I) perchlorate to ligand ratio as 1:2 under the present conditions employed, while with thiourea and N,N-dimethylthiourea, the stoichiometry of the complexes formed between copper (I) perchlorate and ligands is either 1:2 or 1:3 or 1:4 depending upon the conditions
