cis-{Pt(NH3)2(L)}2+/+ (L = Cl, H2O, NH3) Binding to Purines and CO: Does (pi)-Back-Donation Play a Role?

The ability of cis-{Pt(NH3)2(L)}2+/+, a molecular fragment of the anticancer drug cisplatin, to bind to purines and CO by (pi)-backdonation from Pt to the ligand was examined computationally. Optimized geometries and computed vibrational frequencies suggest that cis-{Pt(NH3)2(L)}2+/+ (L = Cl, H2O, NH3) is a poor (pi)-donor and that (pi)-back-donation does not play an important role for Pt(II)ligand interactions in general.