Synthesis, characterization and spectroscopic studies of cyclometalated platinum(II) complexes containing meta-bis(2-pyridoxy)benzene

A series of mononuclear and binuclear cyclometalated platinum(II) complexes containing new terdentate meta-bis(2-pyridoxy)benzene ligands: 3,5-bis(2-pyridoxy)toluene (L1H) and 3,5-bis(2-pyridoxy)-2-dodecylbenzene (L2H): [Pt(L-1)Cl] (1), [Pt(L-2)Cl] (2), [Pt(L-1)(CH3CN)](ClO4) (3), J[Pt(L-1)](2)(mu-dppm)}(ClO4)(2) (4), {[Pt(L-2)]mu-dppm))(ClO4)(2) (5), ([Pt(L-1)](2)(mu-pyrazole))(ClO4) (6), [Pt(L-2)](2)(mu-pyrazole)}(ClO4) (7), {[Pt(L-1)12(mu-imidazole))(ClO4) (8) and {[Pt(L-2)](2)(mu-imidazole)J(ClO4) (9), have been synthesized and characterized. These ligands are coordinated to platinum(II) in a "pincer"-like manner and the presence of pyridyl donors enhances the availability of the ligand pi* orbitals for electronic transition. Spectroscopic properties of these cyclometalated complexes were studied. While the non-coplanar nature of the ligands hinders ligand-ligand and metal-metal interactions in these cyclometalated complexes, the presence of long hydrocarbon side chain on ligand L2H seems to alleviate such hindrance. Intermolecular pi-pi, and possibly Pt-Pt interactions were observed in complex 2 at high concentration. (C) 2004 Elsevier B.V. All rights reserved.