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(L1)Cl] (1), [Pt(L2)Cl] (2), [Pt(L1) (CH3CN)](ClO4) (3), {[Pt(L1)]2(μ-dppm)}(ClO4)2(4), {[Pt(L2)]2(μ-dppm)} (ClO4)2(5), {[Pt(L1)]2(μ-pyrazole)}(ClO4) (6), {[Pt(L2)]2(μ-pyrazole)}(ClO4) (7), {[Pt(L1)]2(μ-imidazole)}(ClO4) (8) and {[Pt(L2)]2(μ-imidazole)} (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 π* 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, and possibly Pt-Pt interactions were observed in complex 2 at high concentration.