FIRST TRANSITION ROW METAL-COMPLEXES WITH RAHYDRO-5,7-DIOXO-[1,2,4]TRIAZOLO[1,5-A]PYRIMIDINE

Complexes of 5,6,7-tetrahydro-5,7-dioxo-[l,2,4]triazolo-[l,5-a] pyrimi dine (H(2)tpO(2)) with the divalent transition metals of the first tra nsition series from Mn to Zn have been synthesized and characterized, their general formula being M(HtpO(2))(2). nH(2)O. The crystal structu re;of the manganese compound, [Mn(HtpO(2))(2)(H2O)(2)], has been solve d by single crystal X-ray diffraction, showing that the ligand binds b identately through the exocyclic oxygen O7 and the endocyclic nitrogen N1, The deprotonation of the ligand takes place at the active methyle ne group at position 6, as it happened in Na(HtpO(2)).2H2O, and not at the N-H group at position 4. Infrared data suggest that the ligand bi nds in a Similar fashion In the Fe, Co, Ni and Zn compounds but not in the copper one. This has been corroborated by powder X-ray diffractio n, which indicates that all compounds except Cu are isostructural. (C) 1998 Elsevier Science Ltd. All rights reserved.