Studies on Azido Complexes of Cobalt. Part-III : Photochemical Studies

Department of Pure Chemistry, University College of Science, Calcutta-700 009

Department of Applied Chemistry, University College of Technology, Calcutta 700 009

Manuscript received 28 April 1930, revised 21 August 1983, accepted 26 November 1983

The effect of viscosity, concentration and pH on the photochemical reduction of Co(III) to Co(II) on irradiation with light of 254, 313, 365 nm have been investigated for complexes of the type [CoL₂(N3)₂,]+1 (L =ethylene diamine, 2,2'-bipyridyl, 1,10- phenanthroline, biguanide) and also for cis- and trans-[Co(en)₂(NO₂)(H₂O)]²⁺. Results show that for a particular exciting light ^\(\phi\)C 2+ is affected only by the viscosity of the photolytic medium and is independent of the concentration of the complex, and pH. It has also been observed that for cis- and trans-[Co(en)₂(N₃)₂]CIO₄ the redox quantum yield goes through a maximum and the ^\(\phi\) redox vs wave length profile is almost parallel to the contour of the uv absorption spectra.

Investigations show that the bisazido complexes on excitation in the charge transfer spectral region in nonaqueous media undergo photodecomposition without the formation of Co(II).