Inorganica Chimica Acta. 172 (1990) 253- 258 253 Zn(II) and Hg(I1) Complexes of 4,6-Diamino-2-thiopyrimidine and 4,6-Diamino-2-methylthiopyrimidine. Crystal Structure of 4,6-Diamino-2-methylthiopyrimidinium Hemitetrachlorozincate(I1) zyxwvutsrqponmlkjihgfedcbaZY M. A. ROMERO, J. M. SALAS*, R. Lt)PEZ, M. D. GUTIkRREZ Department of Inorganic Chemistry, University of Granada, 18071 Granada (Spain) K. PANNEERSELVAM, K. K. CHACKO* Department of Crystallography and Biophysics, University of Madras, Madras 600 025 (India) K. AOKI* Department of Materials Science, Toyohashi University of Technology, Tempaku- cho, Toy ohashi 440 (Japan) and H. YAMAZAKI The institute of Physical and Chemical Research, W ako-shi, Saitama 351-01 (Japan) (Received September 4,1989) Abstract Reaction of Zn(I1) and Hg(II) with 4,6-diamino-2- thiopyrimidine (DATP) and 4,6-diamino-2-methyl- thiopyrimidine (DAMTP) in aqueous medium gave six new compounds which have been characterized by elemental analysis, IR and ‘H NMR spectroscopic techniques. The crystal structure of the Zn(I1) com- plex of DAMTP has been determined by X-ray diffraction. It crystallizes in the trigonal space group p3r21 (or P3,21), a = 8.725(2), c =24.288(4) A, C5H9C12N4SZn,-,,, 2 = 6, Dcalc= 1.616 g cme3 and R = 0.045 for 1056 unique reflections. The com- pound forms a salt structure composed of a 4,6- diamino-2-methylthiopyrhnidinium cation with the ring nitrogen Nl protonated and a hemitetrachloro- zincate anion. The crystal packing is dominated by a threedimensional network of N-H.. .Cl hydrogen bonds. Introduction Purines and pyrimidines are the main constituents of nucleic acids and play important roles in many biological systems. Substituted purines and pyri- midines are also biologically important [l-4]. Among pyrimidine derivatives, thiopyrimidines are of great interest because of their wide biological activities. Some of these derivatives can act as in- hibitors and antimetabolites [5-8].2-Thiopyrimidine shows a strong bacteriostatic activity in vitro on *Authors to whom correspondence should be addressed. 0020-l 693/90/$3 SO E. coli [9]. Likewise, 6-amino-2-thiouracil is well known as an antiviral [lo] or a chemotherapeutic [lo-121 agent. Also because of the biological impor- tance of the metal complex formation processes of these pyrimidine derivatives, their interactions with metal ions have been widely investigated [ 131. As the continuation of our works on metal inter- actions with thiopyrimidine and thiopurine deriva- tives [ 141, we report here the synthesis of six new compounds, formed from Zn(I1) or Hg(I1) and 4,6- diamino-1,2-dihydro-2-thiopyrimidine (DATP) or 4,6- diamino-2-methylthiopyrimidine (DAMTP), and the crystal structure of [HDAMTP] 2 [ZnC14]. Although X-ray [ 151 as well as solution [ 161 studies of Zn(I1) or Hg(I1) complexes with nucleic acid constituents are numerous, only a limited number of investigations of Zn(I1) or Hg(I1) complexes with thiopyrimidines, which are all X-ray works, are available [ 171. Experimental Preparations DA TP and DAMTP Thiopyrimidine derivatives were synthesized using methods previously described [18, 193. Zn(DATP)& (I), Hg3(DATP)Q6 (5) and Hgs(DAMTP),Cl6 (6) The corresponding thiopyrimidine derivative (2 mmol) was added to a hot solution (60 “C) of ZnClz or HgClz (6 mmol) dissolved in the minimum amount of water. Both Hg(I1) complexes precipitated imme- diately. Zn(I1) complex formed after one day by slow 0 Elsevier Sequoia/Printed in Switzerland