title: Structural and spectroscopic characterizations of tetra-nuclear niobium(V) complexes of quinolinol derivatives.
abstract: Reactions between niobium ethoxide and 8-hydroxy-2-methylquinoline or 5-chloro-8-hydroxyquinoline have been explored. Two new tetranuclear heteroleptic niobium complexes containing oxo, ethoxo, and quinolinate chelate rings have been synthesized and characterized by (1)H, (13)C and (93)Nb NMR, UV-Vis, and FT-IR spectroscopies, and single-crystal X-ray diffraction. The molecular structures of the niobium complexes, [Nb4(μ-O)4(μ-OEt)2(ONC10H8)2(OEt)8] (I) and [Nb4(μ-O)4(μ-OEt)2(ONC9H5Cl)2(OEt)8] (II), are composed of a pair of edge-sharing bioctahedral moieties in which connected via two almost linear oxo-bridges, with a large difference in the NbO distances. Single-crystal structures showed both complexes are centrosymmetric and contain two distinct Nb centers, and results confirmed by observation of two niobium signals in the (93)Nb NMR spectra of complexes.
authors.affiliation: Department of Chemistry, Shahid Beheshti University G.C., Tehran 1983963113, Iran. Electronic address: m-pouramini@sbu.ac.ir.
authors.forename: Mostafa M
authors.initials: MM
authors.lastname: Amini
authors.affiliation: Agricultural, Medical and Industrial Research School (AMIRS), Nuclear Science and Technology Research Institute (NSTRI), Karaj, 31485-498, Iran.
authors.forename: Yousef
authors.initials: Y
authors.lastname: Fazaeli
authors.affiliation: Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran. Electronic address: mohammadnezhad@cc.iut.ac.ir.
authors.forename: Gholamhossein
authors.initials: G
authors.lastname: Mohammadnezhad
authors.affiliation: Department of Chemistry, Shahid Beheshti University G.C., Tehran 1983963113, Iran.
authors.forename: Hamid Reza
authors.initials: HR
authors.lastname: Khavasi
mesh_terms: D066241:Carbon-13 Magnetic Resonance Spectroscopy; D018360:Crystallography, X-Ray; D006912:Hydroxyquinolines / Q000737:chemistry*; D008968:Molecular Conformation; D009556:Niobium / Q000737:chemistry*; D066244:Proton Magnetic Resonance Spectroscopy; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D006912:Hydroxyquinolines; D009556:Niobium
keywords: 8-Hydroxyquinoline; Alkoxide; Crystal structure; Niobium; Spectroscopy; Tetranulear