Aquabis(2-methyl-4-oxopyrido[1,2-a]pyrimidin-9-olato)cobalt (II): Crystal Structure and Spectroscopic Properties

Abstract  

The title cobalt complex, Co(C₉H₇N₂O₂)₂H₂O]H₂O, has been synthesized by the reaction of ligand, 9-hydroxy-2-methyl-4H-pyrido1,2-a]pyrimidine-4-one (HL), and cobalt nitrate. The synthesized complex was characterized by IR, elemental analysis (C, H and N), mass spectrometry and X-ray crystallography. The structure was solved in monoclinic, space group P2₁/c with a = 14.4584(13), b = 6.9385(8), c = 18.045(2) ?, β = 94.8440(10), V = 1803.8(3) ?³, Z = 4, and with R _int = 0.034. The Co(II) complex, as shown by the single-crystal structure determination, existed as a mononuclear complex with distorted square-pyramidal geometry. The mental center was coordinated by two molecules from the bidentate ligand (HL) and an O atom from the coordinated water molecule. The intermolecular aromatic π–π stacking interactions generate discrete dimers. Furthermore, these discrete dimers were connected via O–H···O hydrogen bond in complex to form three-dimensional networks. At room temperature, the complex can emit blue luminescence at 430 nm in the solid state, while it about 42 nm blue-shifted in ethanol solution. Compared with free ligand, the luminescence was greatly intensified.