SPECTROCHEMICAL STUDIES ON THE 4,6-DIAMINE-2- METHYLTHIO+NITROSO PYRIMIDINE COMPLEXES OF Pd(II), PW, AgO, AWQ, Cd0 AND Hg(IU M. A. ROMERO,” J. M. SALAS, R. LOPEZ and M. D. GUTIRRREZ Departamento de Quimica InorgBnica, Universidad de Granada, 18071 Granada, Spain (Received 25 June 1987 ; accepted 16 December 1987) Abstract-The Pd(II), Pt(II), Ag(I), Au(III), Cd(I1) and Hg(I1) complexes of 4,6-diamine- 2-methylthio-5-nitroso pyrimidine (H,DAMTNP) have been prepared and investigated by IR, ‘H NMR and magnetic methods: M(HIDAMTNP)ZX2 (M = Hg, X = Cl; M = Pd, X = Br ; M = Pt, X = Cl, Br), Cd(H2DAMTNP)C12, Pd(HDAMTNP)Cl, Au(DAMTNP)Cl and Ag(HDAMTNP) * H20. The ligand is S-coordinated to the metal in Cd(I1) and Pt(I1) complexes ; for the remaining complexes IR spectra suggest coordination involving N&chelation of the ligand through the ring nitrogen atom and exocyclic sulphur atom. Metal halogen coordination has been assigned on the basis of the position of v(M-X) in the far-IR spectra. From DSC and TG curves, the thermal behaviour of these complexes has been deduced. The stimulus for much of the research into the coordination chemistry of heterocyclic thione donors stems from the wide range of applications of the complexes of such ligands, mainly those derived from their biological activity. ’ Medical-biological bacteriostatic activity has been related to coor- dination ability of some thione imidazoline and thi- azoline derivatives,* and zinc pyridine thione has a bacteriostatic activity.3 Other thione derivatives have thyrotoxic4 or anticonvulsant activities or cen- tral nervous system depressant capacity. 5 Finally, carcinostatic activity of some of their heavy metal complexes has been reported6 and a platinum pyridine thione cdmplex has been patented for use in cancer treatment. 7 vention of complex formation processes in the bio- logical action mechanism of these pyrimidine derivatives. ’ 6 659 In the last few years we have published some papers concerning the study of metal complex for- mation of several 2-methylthiopyrimidine deriva- tives.‘7W25 Most recently the X-ray study of a Cd(I1) complex with 4,6-diamino-l,Zdihydro-2-thiopy- rimidine has been published.26 As a continuance of these works, in the present paper we report the synthesis and study of eight new complexes, formed by the reactions between Cd(II), Hg(II), Pd(II), Pt(II), Ag(1) and Au(II1) and 4,6-diamino-2- methylthio-5-nitroso pyrimidine (H,DAMTNP). Among the heterocyclic derivatives with sulphur in their molecules, the thiopyrimidine derivatives are very important because of their wide biological activity. Some of these derivatives can act as inhibi- tors”’ and antimetabolites. ’ @’ ’ 2-Thiopyrimidine shows a strong in vitro bacteriostatic activity on E. Coli. I2 Likewise 6-amino-2-thiouracile is well known because of its antiviral’ 3 and chemi- therapeutic activities.‘p’5 On the other hand, in many cases it seems probable that there is inter- Methods The pyrimidine derivative, H,DAMTNP, was prepared following a previously reported methodz7 using analytical reagent grade chemicals. * Author to whom correspondence should be addressed. The complexes were prepared as follows : 1.1 mmol of HzDAMTNP was dissolved in the mini- mum amount of water (ethanol was used for the preparation of the Cd(I1) complex) at 40°C. Then an aqueous solution of the corresponding metallic salt was added (AgNO,, Cd(I1) and Hg(I1) chlor- EXPERIMENTAL