Decorating Diruthenium Compounds with Fréchet Dendrons via the Click Reaction

A series of dendronized-Ru2 compounds were prepared using the Cu(I)-catalyzed 1,3-dipolar cycloaddition (click reaction) between the terminal azides of azidopoly(benzyl ether) dendrons ([Dn]-N3, n = 0–3) and Ru2 units bearing one or two terminal ethynes, Ru2(D(3,5-Cl2Ph)F)4–m(DMBA-4-C2H)mCl with m = 1 and 2, and D(3,5-Cl2Ph)F and DMBA-4-C2H as N,N′-bis(3,5-dichloro-phenyl)formamidinate and N,N′-dimethyl-4-ethynylbenzamidinate, respectively. The resultant Ru2(D(3,5-Cl2Ph)F)4–m(DMBA-Dn)mCl compounds were further functionalized by the axial ligand displacement of Cl by -C2Ph to yield new compounds Ru2(D(3,5-Cl2Ph)F)4–m(DMBA-Dn)m(C2Ph)2 (where m = 1 and 2; n = 0 and 1). All Ru2 compounds reported herein were analyzed via mass spectrometry, voltammetry, and UV–visible and fluorescence spectroscopy. Density-functional theory (DFT) calculations were performed on a model compound to gain more insight into the molecular orbital energy levels possibly associated with the photophysical data obtained and presented herein.