En Route Activity of Hydration Water Allied with Uranyl (UO22+) Salts Amid Complexation Reactions with an Organothio-Based (O, N, S) Donor Base.

ABSTRACT

This study provides en route activity of hydration water allied with uranyl salts amid complexation reactions with a donor species L bearing O, N, and S (phenolic, -OH; imine, -HC═N-; and thio-, -S-) donor functionalities. The UO22+/L reaction encounters a series of hydrolytic steps with hydration water released from uranyl salts during the complexation processes. Primarily, the coordinated [L(-HC=N)(OH)(-HC=N) → UO2(NO3)2/(OAc)2] species formed during the complexation process undergoes partial hydrolysis of the coordinated ligand resulting in the isolation of an aldehyde coordinated uranyl species [L(-HC=N)(OH)(-HC=O) → UO2(NO3)2/(OAc)2]. The influence of hydration water continued as the reaction further proceeded to the next stage resulting in alteration of the aldehyde coordinated uranyl species [L(-HC=N)(OH)(-HC=O) → UO2(NO3)2/(OAc)2] to an oxidized carboxy coordinated uranyl species [L(-HC=N) (OH){-C(═O)O} → (NO3)/(OAc)]2 without the use of any external oxidizing agents. These studies are of particular significance as they allow one to realize the adventitious role of hydration water released from commonly used uranyl salts during their reaction with organic donor substrates in nonaqueous medium. These results also form an experimental basis to understand the critical behavior of UO22+ ion activity (as oxidizing, reducing, or catalytic) relevant in many chemical, biological, and environmental processes.