Reactivity of Coordinated 2-Pyridyl Oximes: Synthesis, Structure, Spectroscopic Characterization and Theoretical Studies of Dichlorodi{(2-Pyridyl)Furoxan}Zinc(II) Obtained from the Reaction between Zinc(II) Nitrate and Pyridine-2-Chloroxime

Density Functional Study to Investigate the Ability of (ZnS)n (n = 1-12) Clusters Removing Hg0, HgCl, and HgCl2 via Electron Localization Function and Non-Covalent Interactions Analyses

In this study, the density functional theory is used to study the ability of (ZnS)_n clusters to remove Hg⁰, HgCl, and HgCl₂ and reveals that they can be absorbed on (ZnS)_n clusters. According to electron localization function (ELF) and non-covalent interactions (NCI) analyses, the adsorption of Hg⁰ on (ZnS)_n is physical adsorption and the adsorption ability of (ZnS)_n for removing Hg⁰ is weak. When (ZnS)_n adsorbs HgCl and HgCl₂, two new Hg-S and Zn-Cl bonds form in the resultant clusters. An ELF analysis identifies the formation of Hg-S and Zn-Cl bonds in (ZnS)_nHgCl and (ZnS)_nHgCl₂. A partial density of states and charge analysis confirm that as Hg⁰, HgCl, and HgCl₂ approach (ZnS)_n clusters, atomic orbitals in Hg and Zn, Hg and S, as well as Zn and Cl overlap and hybridize. Adsorption energies of HgCl and HgCl₂ on (ZnS)_n clusters are obviously bigger than those of Hg⁰, indicating that HgCl and HgCl₂ adsorption on (ZnS)_n clusters is much stronger than that of Hg⁰. By combining ELF analysis, NCI analysis, and adsorption energies, the adsorption of HgCl, and HgCl₂ on (ZnS)_n clusters can be classified as chemical adsorption. The adsorption ability of (ZnS)_n clusters for removing HgCl and HgCl₂ is higher than that of Hg⁰.

Dinuclear Lanthanide(III) Complexes from the Use of Methyl 2-Pyridyl Ketoxime: Synthetic, Structural, and Physical Studies

The first use of methyl 2-pyridyl ketoxime (mepaoH) in homometallic lanthanide(III) [Ln(III)] chemistry is described. The 1:2 reactions of Ln(NO3)3·nH2O (Ln = Nd, Eu, Gd, Tb, Dy; n = 5, 6) and mepaoH in MeCN have provided access to complexes [Ln2(O2CMe)4(NO3)2(mepaoH)2] (Ln = Nd, 1; Ln = Eu, 2; Ln = Gd, 3; Ln = Tb, 4; Ln = Dy, 5); the acetato ligands derive from the LnIII-mediated hydrolysis of MeCN. The 1:1 and 1:2 reactions between Dy(O2CMe)3·4H2O and mepaoH in MeOH/MeCN led to the all-acetato complex [Dy2(O2CMe)6(mepaoH)2] (6). Treatment of 6 with one equivalent of HNO3 gave 5. The structures of 1, 5, and 6 were solved by single-crystal X-ray crystallography. Elemental analyses and IR spectroscopy provide strong evidence that 2-4 display similar structural characteristics with 1 and 5. The structures of 1-5 consist of dinuclear molecules in which the two LnIII centers are bridged by two bidentate bridging (η1:η1:μ2) and two chelating-bridging (η1:η2:μ2) acetate groups. The LnIII atoms are each chelated by a N,N'-bidentate mepaoH ligand and a near-symmetrical bidentate nitrato group. The molecular structure of 6 is similar to that of 5, the main difference being the presence of two chelating acetato groups in the former instead of the two chelating nitrato groups in the latter. The geometry of the 9-coordinate LnIII centers in 1, 5 and 6 can be best described as a muffin-type (MFF-9). The 3D lattices of the isomorphous 1 and 5 are built through H-bonding, π⋯π stacking and C-H⋯π interactions, while the 3D architecture of 6 is stabilized by H bonds. The IR spectra of the complexes are discussed in terms of the coordination modes of the organic and inorganic ligands involved. The Eu(III) complex 2 displays a red, metal-ion centered emission in the solid state; the TbIII atom in solid 4 emits light in the same region with the ligand. Magnetic susceptibility studies in the 2.0-300 K range reveal weak antiferromagnetic intramolecular GdIII…GdIII exchange interactions in 3; the J value is -0.09(1) cm-1 based on the spin Hamiltonian Ĥ = -J(ŜGd1·ŜGd2).