The synthesis and characterization of three nuclear Pt2Pd2 (4, 5) and PtPd2 (6) complexes of the model nucleobase 9-methyladenine (9-MeA) is reported. The compounds were prepared by reacting [Pt(NH3)(3)(9-MeA-N7)] (ClO)(2) (1) with [Pd(en)(H2O)(2)](ClO4)(2) at different ratios r between Pt and Pd, with the goal to probe Pd-II binding to any of the three available nitrogen atoms, N1, N3, N6 or combinations thereof. Pd-II coordination occurs at N1 and at the deprotonated N6 positions, yet not at N3. 4 and 5 are isomers of [{(en)Pd}(2){N1,N6-9-MeA(-)-N7)Pt(NH3)(3)}(2)](ClO4)(6)center dot nH(2)O, with a head head orientation of the two bridging 9-MeA(-) ligands in 4 and a head tail orientation in 5.6 is [{(en)Pd}(2)(OH)(N1,N6-9MeA(-)-N7)Pt(NH3)(3)] (ClO4)(4)center dot 4H(2)O, hence a the N1 and N6 positions of 9-MeA(-) in an intramolecular fashion. 4 and 5, which slowly interconvert in aqueous solution, display distinct structural differences such as significantly different intramolecular Pd center dot center dot center dot Pd contacts (3.124 0(16) angstrom in 4; 2.986 6(14) angstrom in 5), among others. Binding of (en)Pd-II to the exocyclic N6 atom in 4 and 5 is accompanied by a large movement of Pdu out of the 9-MeA(-) plane and a trend to a further shortening of the C6-N6 bond as compared to free 9-MeA. The packing patterns of 4 and 5 reveal substantial anion-pi interactions.