Aquation of cis-dichlorobis(biguanide)ruthenium (III) chloride in aqueous-organic solvent

Abstract

Aquation of <em>cis</em>-Ru^III(BigH)₂Cl<img src='http://www.niscair.res.in/jinfo/plustwo.gif' border=0> has been investigated in water as well as in aquo-organic solvents containing MeOH, EtOH and acetone. The reaction occurs in steps with the formation of Ru(BigH)₂(H₂O)Cl²⁺ and finally Ru(BigH)₂(H₂O)<img src='http://www.niscair.res.in/jinfo/equation28.gif' border=0>. Activation parameters for the first step (D<em>H</em><img src='http://www.niscair.res.in/jinfo/equation145.gif' border=0> 17 ± 4 kJ mol^-1 and DS<img src='http://www.niscair.res.in/jinfo/equation145.gif' border=0> - 236 ± 10 J K^-1 mol^-1) indicate that a redox process takes place in this step. Activation parameters for the second step (<img src='http://www.niscair.res.in/jinfo/delta.gif' border=0><em>H</em><img src='http://www.niscair.res.in/jinfo/equation146.gif' border=0> 77 ± 4 kJ mol^-1 and <img src='http://www.niscair.res.in/jinfo/delta.gif' border=0>S<img src='http://www.niscair.res.in/jinfo/equation146.gif' border=0> - 236 ± 8 J K^-1 mol^-1) indicate an aquation process. In mixed solvents, as the percentage of water decreases the rates of aquation for both the stages also decrease.