MERCURY(II) COMPLEXES OF YDRO-5-METHYL-7-OXO[1,2,4]TRIAZOLO[1,5A]PYRIMIDINE - STABILIZATION OF 2 CHEMICALLY DIFFERENT METAL COORDINATION ENVIRONMENTS BY HYDROGEN-BONDING ASSEMBLY

The reaction of HgCl2 with 4,7-dihydro-5-methyl-7-oxo[1,2,4] triazolo [1,5a]pyrimidine (Hmtpo) in aqueous media yields complexes of formula HgCl2(Hmtpo) (1) and {[HgCl2(Hmtpo)](2) . Hmtpo . H2O}(n) (2). The cry stal structure of compound 2 has been solved by X-ray diffraction. The structure is built on two different HgCl2(Hmtpo) entities and solvati on water and Hmtpo molecules. In both cases, the metal atoms are locat ed in a distorted trigonal geometry comprising two chlorine atoms and a nitrogen atom N1 from the Hmtpo ring, this coordination mode being u nusual for this ligand. Mercury atoms also interact weakly with chlori ne atoms from neighbouring HgCl(2)Hmtpo units, generating a single and a double chain which grow along the crystallographic a axis. Noncoord inated Hmtpo and water molecules link the chains in a very interesting hydrogen bonding pattern. Finally, a relation between strength of lig and-HgCl2 interactions and the coordination discussed.