THE KINETICS AND MECHANISM OF THE FORMATION OF THIOCYANATO-BRIDGED DINUCLEAR COMPLEX ION [RU-2(NH3)(8)(SCN)(3)](3+)

摘要

Formation of a thiocyanato-bridged dinuclear complex [Ru-2(NH3)(8)(SCN)(3)](3+) by the interaction of [Ru(NH3)(5)Cl](2+) and SCN- was investigated in aqueous solution between 48 and 59 degrees C. The reaction proceeds in two stages. First stage proceeds with ion-pair formation between the reacting species giving [Ru(NH3)(4)(SCN)Cl](+) with the loss of one coordinated ammonia. The second stage comprises ''ion-aggregation'' of this tetraamine complex with another SCN- ion leading to the formation of the SCN- bridged dinuclear complex ion. Activation parameters (Delta H-double dagger 96 +/- 8 and 56 +/- 8 kJ mol(-1) and Delta S-double dagger - 17 +/- 20 and - 125 +/- 21 JK(-1) mol(-1) respectively for the first and second stages of reaction) are consistent with other similar processes and support the mechanism proposed. [References: 16]