Resolution and characterization of helicate dimer and trimer complexes of 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane with copper(I)

Complexation of copper(I) with the binucleating ligand, 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)-propane, mphenpr, result in formation of helical dimers, [Cu-2(mphenpr)(2)](2+). The resolution of the enantiomeric forms of the dimers has been carried out with Delta-[As(cat)(3)](-) as resolving agent and X-ray structures for two compounds, P-[Cu-2(mphenpr)(2)](Delta-[As(cat)(3)])(2) and P-[Cu-2(mphenpr)(2)](Delta-[As(cat)(3)])(2)center dot 4(CH3CN), are reported. The rate of racemization in poorly-coordinating solvents has been examined by 1H NMR, and is slow. At saturating concentrations of [[Cu-2(mphenpr)(2)](2+)] in acetonitrile, crystals of the helical trimeric complex [Cu-3(mphenpr)(3)](ClO4)(3) are obtained. The X-ray structure of the trimer is reported. This species has also been resolved. As with the helical dimer, racemization in poorly-coordinating solvents is slow, and circular dichroism and H-1 NMR spectra are reported. The absolute configuration of the resolved complex, P-[Cu-3(mphenpr)(3)](Delta-[As(cat)(3)])(3), has been determined by X-ray crystallography.