Supramolecular Aggregates of Complex Cations via Unusual Purine−Purine Base Pairing in a New Organorhodium(III) Compound Containing the Antileukemic Drug Purine-6-thione. Synthesis, X-ray Structure of trans ( C , N 7 ), trans ( S , S ), trans ( P , N 7 )-[Rh(C 6 H 5 )(H 1 ,H 9 - H 2 tp) 2 (PPh 3 )][Rh(C 6 H 5 )(H 1 ,H 9 -H 2 tp)(H 9 - Htp)(PPh 3 )]Cl 3 ·HCl·6H 2 O, and Density Functional Analysis of the {H 2 tp···Htp} - Base Pair