Investigating the reactivity of neutral water-soluble Ru(ii)-PTA carbonyls towards the model imine ligands pyridine and 2,2'-bipyridine.

As a continuation of our strategy for preparing new Ru(ii) precursors to be exploited as building blocks in the construction of metal-mediated supramolecular assemblies with improved solubility in water, here we describe the reactivity of selected neutral Ru(ii)-PTA carbonyls (PTA = 1,3,5-triaza-7-phosphaadamantane) towards the model imine ligands pyridine (py) and 2,2'-bipyridine (bpy) and the preparation and characterization of several neutral and cationic water-soluble derivatives: ,,-[RuCl(CO)(py)(PTA)] (7), ,,-[RuCl(CO)(py)(PTA)] (9), ,-[Ru(bpy)Cl(CO)(PTA)]Cl (10), -[Ru(bpy)(CO)(PTA)](Cl) (12), ,-[Ru(bpy)(CO)Cl(PTA)]Cl (13), ,-[Ru(bpy)(CO)(PTA)](NO) (14NO). In addition, we found that light-induced isomerization in some bpy compounds could be induced. The following species, either side-products isolated in low yield or compounds obtained exclusively in solution, were also unambiguously identified: ,,-[RuCl(CO)(py)(PTA)] (8), -[RuCl(bpy)(CO)(PTA)] (11), ,-[Ru(bpy)Cl(CO)(PTA)]Cl (15) and ,-[Ru(bpy)(CO)Cl(PTA)]Cl (16). The X-ray structures of 7, 11·HO, and 12·7HO are also reported. All compounds are new and - with few exceptions - show a good solubility in water.