Ternary Complexes of Some Metal Ions with 2,2'-Bipyridyl or 1,10-Phenanthroline as Primary Ligand and Naptalam as a Secondary Ligand

Department of Chemistry, V. S. B. D. College (Kanpur University), Kanpur-208 002

Manuscript received 8 September 1981, revised 15 June 1982, accepted 12 November 1982

In order to explore complexation as a possible mode of action of some pesticides, the binary and ternary complexes of the type MAL⁺, where M=Co(II), Ni(II), Cu(II), or Zn(II), A=2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen) and L= naptalam, have been studied potentiometrically in solution. Protonation constant of naptalam and the stability constants of its binary as well as ternary complexes have been reported at constant ionic strength (0.1 M KNO₃) and temperature (25°) The values of characterising constant (∆ log K) have been found to be positive, zero or small negative. These values have been used to interpret the extent of M→N-base π-Interactions in these systems. On the basis of formation of considerably stable binary and ternary metal complexes of these pesticides, a new mechanism for their mode of action has been proposed.