Synthesis and crystal structures of complexes of MnII, CuII and ZnII with the new bis(tridentate) chelate 2,3,5,6-tetrakis(aminomethyl)pyrazine

Abstract

The new bis(tridentate) chelate 2,3,5,6-tetrakis(aminomethyl)pyrazine (tampyz) has been prepared. It forms a quasi-linear one-dimensional polymeric complex with MnCl₂ in water. [{Mn(tampyz)Cl₂·2H₂O}_∞]. The crystal structure reveals that it is the first infinite co-ordination polymer with a regular metal–ligand arrangement where the metal atom is fully co-ordinated by all six functional groups of the ligand. The binuclear complex [Cu₂(tampyz)Cl₂]Cl₂·2.25H₂O was obtained by the reaction of Cu(O₃SC₆H₄Me-P)₂·5H₂O and [H₄tampyz]Cl₄ in water, and its crystal structure determined. The copper atoms can be considered to be either four-co-ordinate in a square-planar environment, or six-co-ordinate with two weak apical Cu ⋯ Cl bonds so forming a ladder-type polymer. The binuclear complex [Cl₂Zn(tampyz)ZnCl₂] was prepared by the reaction of ZnCl₂ and tampyz in water. Its crystal structure reveals that the zinc atoms are five-co-ordinate in a trigonal-bipyramidal arrangement. The two Zn–Cl bonds are equivalent, as expected for a d¹⁰ complex.