Synthesis, Structures, and Photoluminescent Properties of Manganese(II) Complexes with 3-Chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridazine
摘要
Manganese(II) complexes based on 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridazine (L) with different anions (bromide, perchlorate and salicylate) have been synthesized and structurally characterized. Complex compounds [MnL2Br2] (I), [MnL2(H2O)2](ClO4)2 (II), and [Mn3L2(Sal)6]·2CH3CN (III) have been obtained by a reaction of appropriate manganese(II) salts and L in organic media at a molar ratio of 1 : 1. According to the single-crystal X-ray diffraction, complexes I and II have a mononuclear molecular structure and an ionic structure, respectively, and complex III has a trinuclear molecular structure. The Mn centers in these solids exhibit a distorted octahedral coordination geometry, the coordination polyhedron in I, II, and III is MnN4Br2, MnN4O2, and Mn(1)N2O4 or Mn(2)O6, respectively. The photoluminescent properties for complexes I–III have been studied in the solid state and in solution. The absorption spectrum of III as compared to the spectrum of ligand L shows new bands at 310 and 340 nm; upon excitation in this region a dual-band emission with maxima at 390 and 445 nm with nanosecond lifetimes is observed. Solid complex III shows weak phosphorescence (λmax = 420 nm). Upon cooling at 77 K, in the PL spectrum of III two additional bands (520 and 585 nm) appear, and bands at 520 and 460 nm are observed in the excitation spectrum, due to transitions in the Mn2+ ion. For complexes I and III, the values of the effective magnetic moment at 300 K were determined to be 5.82 and 5.70 µB, respectively.