Synthesis, crystal structure, hydrogen bonding and spectroscopy of transition-metal complexes with the ligand (N,N′-bis(2-pyridylmethyl)-1,3-propanediamine)

Six mononuclear complexes are reported with the tetradentate ligand N,N′-bis(2-pyridylmethyl)-1,3-propanediamine, (abbreviated as pypn) i.e. [Cu(pypn)(ClO4)2](H2O)1/2 (1), [Fe(pypn)Cl2](NO3) (2), [Zn(pypn)Cl](ClO4) (3), [Co(pypn)(NCS)2](ClO4) (4), [Co(pypn)(N3)2](ClO4) (5), [Zn(pypn)(NCS)2] (6). The synthesis and X-ray crystal structures of all six compounds and their spectroscopic properties are presented.The geometry of the Cu2+, Co3+, Zn2+, Fe3+ ions is essentially octahedrally based, with the mm conformation (for Cu) and msf conformations for the other 3 metal ions; in compound 3 the geometry around the Zn2+ is distorted trigonal bipyramidal. The stabilisation of the crystal lattices is maintained by interesting, relative strong hydrogen bonds.

Graphical abstractThe tetradentate ligand N,N′-bis(2-pyridylmethyl)-1,3-propanediamine can fold around transition-metal ions in 2 ways, generating either 2 cis octahedral positions for anion ligands, or 1 or 2 axial positions in square pyramidal or octahedral geometries.Figure optionsDownload full-size imageDownload as PowerPoint slide