Department of Chemistry, The University of Burdwan, Burdwan-713 104, West Bengal, India E-mail : alakghosh2002@yahoo.co.in Manuscript received online 09 March 2016, accepted 12 March 2016 The kinetics of the interactions of thiourea and L-cysteine with the title complex were studied spectrophoto­metrically as a function of complex and ligand concentrations, pH and temperature at constant ionic strength. The substitution reactions show two consecutive steps : the first is the ligand-assisted anation followed by a chelation step. The activation parameters for both the steps have been evaluated using Eyring equation. The low positive value of ΔH≠ and the large negative value of ΔS≠ indicate an associative mode of activation for both the aqua ligand substitution processes. The products of the reactions have been characterized with the help of infrared and electrospray ionization mass spectroscopic analysis.