| 1. |
- Ma, Guibin
(författare)
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On Thallium (III) and binuclear platinum-thallium complexes with N-donor ligands in solution and in solid
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the synthesis, structure, equilibriaand other properties of novel thallium(III) monomeric andplatinum-bonded complexes with nitrogen donor ligandsethylenediamine, diethylenetriamine, triethylenetetramine,porphyrin, 2,2'-bipyridine and 1,10-phenanthroline in solutionand in solid.The existence of three complexes withthe general formula[Tl(en)n]3+(n = 1-3) and their overall stability constantshave been established in pyridine. All three complexes wereidentified by their205Tl and1H NMR chemical shifts and205Tl-1H coupling constants. The formation process of thecomplexes was followed by1H NMR spectroscopy. The crystal structure of[Tl(en)3](ClO4)3was determined; the thallium(III) ion isN-coordinated in a distorted octahedral geometry. Two [Tl(dien)n]3+(n = 1-2) complexes were proved to exist insolution and the structure of the bis-complex [Tl(dien)2]2+inu-facialisomers was determined in solid. In addition,crystal structures of [Tl(en)2CN](ClO4)2with cyanide bridging between two Tl(en)2units forming an infinite chain structure and of[Tl(tren)2(CN)2](ClO4) with a distorted pseudo-octahedral coordinationaround thallium were determined. Thallium(III) complexes with2,2'-bipyridine and 1,10-phenanthroline have been studied inDMSO using205Tl,13C and1H NMR spectroscopy. In addition, aseven-coordinated thallium was found in the crystal structureof [Tl(bipy)3(dmso)](ClO4)3, and six-coordinated thallium in pseudo-octahedralgeometry in [Tl(phen)2Cl2](ClO4).The solvated complex [Tl(dmso)6]3+has been prepared using concentrated aqueoussolution of Tl(ClO4)3by a solvent replacement reaction in DMSO, and thewater-free solid compound [Tl(dmso)6](ClO4)3was crystallized from DMSO. The structure of thecomplex [Tl(dmso)6]3+is a regular octahedron with the Tl-O bonddistance 2.224(3) Å. It represents an easy and secure wayto introduce water-free Tl(III) into organic phase withoutreduction.Through several reactions, novel heteronuclear Pt-Tlcomplexes with the composition [(NC)5Pt-Tl(tpp)]2-, [(NC)5Pt-Tl(thpp)]2-, [(NC)5Pt-Tl(bipy)n](n = 1-2), [(NC)5Pt-Tl(en)n-1](n = 1-3) and [(NC)5Pt-Tl(phen)n](n = 1-2), have been synthesized in solution.Multinuclear NMR (195Pt,205Tl,13C and1H), Raman spectroscopy and X-ray diffraction dataare fully compatible with formation of unsupported Pt-Tl bondedcomplexes both in solution and in solid. The huge1J(195Pt-205Tl) spin-spin coupling constants (48-66 kHz) wereobserved by both195Pt and205Tl NMR spectroscopy in solution and they providea strong evidence of formation of the Pt-Tl bond in solution.In all six determined crystal structures of the Pt-Tl compoundsa very short Pt-Tl bond is found with distances2.6117(5)-2.6375(5) Å. The calculated values of Pt-Tlforce constants (1.38-1.91 N/cm) are characteristic for asingle metal-metal bond.In the Pt-Tl compounds, the oxidation state of the metalions is intermediate between the stable states PtII/PtIVand TlIII/TlI, respectively, and this is reflected by their195Pt and205Tl chemical shifts. It turns out that N-donorligands can really stabilize the Pt-Tl bond both in solutionand in solid. The character of the metal-metal bond anditstheoretical basis are discussed.Keywords:Thallium, Platinum, Cyanide, N-donor ligand,Metal-metal bond, Multinuclear NMR, Raman spectroscopy, X-raydiffraction, Equilibrium, Spin-spin coupling.
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| 3. |
- Wang, Yawei, et al.
(författare)
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Quantitative structure-activity relationship for prediction of the toxicity of polybrominated diphenyl ether (PBDE) congeners
- 2006
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 64:4, s. 515-524
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Tidskriftsartikel (refereegranskat)abstract
- Levels of Polybrominated diphenyl ether (PBDEs) are increasing in the environment due to their use as flame retardants. The similarities of structure to polychlorinated biphenyl (PCB) congeners suggest that they may share similar toxicological properties, such as hepatic enzyme induction. In this work, quantitative structure-activity relationship (QSAR) models were constructed based on 406 descriptors for the logarithm of toxicology index (aryl hydrocarbon receptor relative binding affinities, AhR, I) of 18 PBDE congeners. The method used for building model is the Heuristic method, which is included in comprehensive descriptors for structural and statistical analysis (CODESSA) software. The best regression model involved four descriptors, which were related to the conformational changes, atomic reactivity, molecular electrostatic field, and non-uniformity of mass distribution in a molecule of PBDEs, etc. The high square of the correlation coefficient R(2)(0.903) showed the model was satisfactory.
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