Synthesis, structural characterization of tetraazamacrocyclic ligand, five-coordinated zinc(II) complex

1,4,7,10-tetrakis(2-cyanoethyl-)-1,4,7,10-tetraazacyclododecane(L) and Zn (1), Y(2), Er(3), Pr(4), Gd(5) complexes with L was synthesized and characterized. All metal complexes are in the general formula: [M(L)(H2O)](NO3)2 (M=Zn, n=1); and [M(L)(NO3)2]NO3·mH2O·nCH3CN (M=Y, Er, m=5, n=0; M=Pr, Gd, m=0, n=1, 1.5). Both ionic nitrate ion and bidentate coordinated nitrate ions are existed in complex 2–5. Structures of diprotonated L and zinc complexes were determined by X-ray diffraction. L was crystallized in diprotonated nitrate salt. In zinc complex, the central metal ion was coordinated with four nitrogen atoms of macrocyclic ligand and oxygen atom of water molecule, which defined a tetragonal pyramidal polyhedron. The bond lengths of ZnN are in the range of 2.160(5)–2.177(6) Å and the bond length of ZnO is 1.918(4) Å.