Synthesis and Substitution Kinetics of Tricarbonylrhenium(I) Dendritic Complexes

Tricarbonylrhenium(I) metallodendrimers functionalized with N,N‐2‐picolylamino chelates have been synthesized by the [2+1] approach. Methanol substitution reactions of the first‐ and second‐generation poly(propylene amine) tetra‐ and octanuclear rhenium metallodendrimers by a range of monodentate nucleophiles (i.e. 4‐dimethylaminopyridine, pyridine, and bromide ions) were investigated and compared to the substitution reactions of an analogous monomeric complex, fac‐[Re(CO)3(N,N‐bidentate)(CH3OH)]+. These detailed kinetic studies reveal that a greater activation is achieved using the metallodendrimers with no direct interactions between the metal centers. First‐ and second‐generation poly(N,N‐2‐picolylamino) dendritic ligands and their corresponding rhenium metallodendrimers were synthesized, together with a mononuclear model complex. Substitution reactions were investigated and kinetic studies revealed second‐order rate constants for the reactions with the monomeric model complex, the metallodendrimers achieving a far greater activation.