New multidentate pyrazolyl-pyridine ligands - Synthesis and structures

Five new multidentate ligands have been prepared containing N,N-bidentate pyrazolyl-pyridine units linked to a central aromatic spacer unit. The ligands 3,3'-bis(3-{pyridin-2-yl}-pyrazol-1-yl-methyl)-p-terphenyl (1), 4,4'-bis(3{pyridin-2-yl}-pyrazol-1-yl) biphenyl (2), and 1,8-bis(3-{pyridin-2-yl}-pyrazol-1-yl-methyl) naphthalene (3) have two bidentate arms and are therefore potentially tetradentate; 2,6-bis(3-{pyridin-2-yl}-pyrazol-1-yl-methyl) pyridine (4) has two bidentate arms with an additional nitrogen-donor in the aromatic spacer unit (a pyridyl group) and is therefore potentially pentadentate; and 1,3,5-trimethyl-2,4,6-tris(3-{pyridin-2-yl}-pyrazol-1-yl-methyl) benzene (5) has three bidentate arms and is therefore potentially hexadentate. The X-ray crystal structures of all of these ligands have been determined.