Dinuclear versus tetranuclear cluster formation in zinc(II) nitrate/di-2-pyridyl ketone chemistry: synthetic, structural and spectroscopic studies

作者：Katsoulakou E; Bekiari V; Raptopoulou CP; Terzis A; Lianos P^*; Manessi Zoupa E; Perlepes SP

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2005, 61(7): 1627-1638.

DOI：10.1016/j.saa.2004.11.065

• di-2-pyridyl ketone-based ligands
• zinc clusters
• single-crystal x-ray crystallography
• IR spectroscopy
• blue photoluminescence

The use of di-2-pyridyl ketone, (py)(2)CO, in zinc(II) nitrate chemistry has yielded a dinuclear complex and a cationic tetranuclear cluster. The 1:1 Zn(NO3)(2)(.)4H(2)O/(py)(2)CO reaction system in EtOH gives [Zn-2(NO3)(2){(PY)(2)C(OEt)O}(2)](.)0.5H(2)O (1(.)0.5H(2)O), whereas the same reaction system in MeCN yields [Zn-4(NO3)(3) {(py)(2)C(OH)O}(4)(H2O)](NO3) (2). The monoanionic derivatives of the hemiacetal and the gem-diol forms of di-2-pyridyl ketone have been derived from the Zn(II)-mediated addition of solvent (EtOH, H2O involved in MeCN) on the carbonyl group of (py)(2)CO. Each (py)(2)C(OEt)O- ion functions as an eta(1):eta(2):eta(1):mu(2) ligand in 1(.)0.5H(2)O chelating the two Zn-II atoms through the 2-pyridyl nitrogen atoms and the common bridging, deprotonated oxygen atom; one asymmetric chelating nitrate completes six coordination at each metal center. The tetranuclear cluster cation of 2 has a cubane topology with the Zn-II ions and the deprotonated oxygen atoms from the four eta(1):eta(3):eta(1):mu(3) (py)C-2(OH)O- ligands occupying alternate vertices. Three monodentate nitrates and one aqua ligand complete the sixth coordination site at the metal ions. The two complexes have been characterized by IR and far-IR spectroscopies. Characteristic bands are discussed in terms of the known structures and the coordination modes of the nitrato ligands. Upon excitation at 371 nm, complex 2 displays blue photoluminescence in the solid state at room temperature with two emission maxima at 430 and 455 nm.

• 出版日期2005-5