Spectrophotometric Determination of Rhenium with N-(4-Methoxy-phenyl)-α-thiopicolinamide and Evaluation of the Stability Constant of the Complex Involved Therein

Department of Inorganic and Analytical Chemistry, Jadavpur University.,Calcutta-700 032

Manuscript received 26 June 1981, accepted 2 February 1982

Rhenium reacts with N-(4-methoxy-phenyl)-α-thiopicolinamide to form a stable reddish brown complex on reduction with stannous chloride in 1.08 M to 1.32 M hydrochloric acid medium and the metal can be estimated by extractive photometry in chloroform medium. The system obeys Beer's Iaw from 1-12 ppm at 430 nm. The molar absorptivity is 7.43 x 10³ and the Sandell's sensitivity is 0.025 µg cm^-2. The metal forms a I : 2 complex (metal to ligand) with the ligand. Stability constant (log K) of the Re-complex has been evaluated by the Leden (7.60) and Rossotti and Rossetti (7.99) methods.