Amino-dialkylated adenines R(2)AdH (R = Me, Et) react with ReCl3(MeCN)(PPh3)(2) to form mer,cis-ReCl3(R(2)AdH)(2)(PPh3) complexes. Attempts to protonate the coordinated adenine with HCl led to the oxidized trans-ReCl4(R(2)AdH)(PPh3) compounds. In both types of complexes, the purine binds via the N3 site of the six-membered ring and makes an intramolecular N9-H ... Cl hydrogen bond with a chloride ligand. A material of composition ReCl4(R(2)AdH)(MeCN) was obtained by reacting R(2)AdH with cis-ReCl4(MeCN)(2). It turned out to be a ReCl4[R-2-AdC(Me)=NH] complex containing a cyclic amidine ligand resulting from the insertion of the acetonitrile C=N group in the N9-H bond of the N3-coordinated adenine unit. Crystal structures were determined for one compound of each type : ReCl3(Me(2)AdH)(2)(PPh3). 2C(6)H(5)CH(3), triclinic, P (1) over bar, a = 14.181(2) Angstrom, b = 17.591(3) Angstrom, c = 19.015(5) Angstrom, alpha = 76.66(2)degrees, beta = 86.80(2)degrees, gamma = 87.02(1)degrees, Z = 4, R = 0.0606; ReCl(Me(2)AdH)(PPh3), triclinic, P (1) over bar, a = 10.391(4) Angstrom, b = 10.801(5) Angstrom, c = 13.651(6) Angstrom, alpha = 89.64(4)degrees, beta = 83.49(3)degrees, gamma = 65.14(4)degrees, Z = 2, R = 0.0432; ReCl4[Me(2)AdC(Me)=NH]. C6H6 . CH2Cl2, monoclinic, P2(1)/c, a = 13.941(3) Angstrom, b = 13.656(3) Angstrom, c = 12.874(2) Angstrom, beta = 105.47(2)degrees, Z = 4, R = 0.0406. Most of the signals in the H-1 NMR spectra of these paramagnetic species could be assigned.