Structural Diversity of Nickel and Manganese Chloride Complexes with Pyridin-2-One

Reactions of NiCl(2)·6H(2)O and pyridin-2-one (C(5)H(5)NO = Hhp) afforded novel molecular complexes, i.e., mononuclear [NiCl(2)(Hhp)(4)] (1), dinuclear [NiCl(2)(Hhp)(H(2)O)(2)](2)(.)2Hhp (3) and [Ni(2)Cl(4)(Hhp)(5)]·2MeCN (4), and an ionic complex [Ni(Hhp)(6)]Cl(2) (2). Single-crystal X-ray analyses revealed two modes of Hhp ligation in these complexes: a monodentate coordination of carbonyl oxygen in all of them and an additional µ(2)-oxygen bridging coordination in the dinuclear complex 4. Three bridging molecules of Hhp span two nickel(II) ions in 4 with a 2.9802 (5) Å separation of the metal ions. Complex 3 is a chlorido-bridged nickel dimer with a planar Ni(2)(µ-Cl)(2) framework. Hydrogen bonds and parallel stacking arrangements of the Hhp molecules govern the connectivity patterns in the crystals, resulting in 1D structures in 1 and 5 or 2D in 3. A single manganese compound [MnCl(2)(Hhp)(4)] (5), isostructural to 1, was isolated under the similar conditions. This is in contrast to four nickel(II) chloride complexes with Hhp. Thermal analyses proved the stability of complexes 1 and 3 in argon up to 145 °C and 100 °C, respectively. The decomposition of 1 and 3 yielded nickel in argon and nickel(II) oxide in air at 800 °C.