Syntheses and Studies of Modified di(2-pyridyl)amine Ligands and Their Linear Trinickel String Complexes
Date Issued
2006
Date
2006
Author(s)
Chiu, Mei-Jyun
DOI
zh-TW
Abstract
The aim of this thesis is to investigate the synthesis, structures, and correlative properties of linear trinickel metal string complexes, where the ligands are 2-pyridyl-2’-thiazolylamine (Hpta) and 2-pyridyl-2’- quinolinylamine (Hpqa).
Hpta and Hpqa ligands have been synthesized and characterized by various techniques. Linear trinickel metal string complexes, [Ni3(μ3-pta)4X2] (X = NCS, CN) and (2,2)-cis form [Ni3(μ3-pqa)4(NCS)2] (X = NCS, CN), have also been synthesized and characterized. The X-ray structural studies reveal the terminal nickel ions with five-coordinate and the inner nickel ion with four-coordinate. Due to asymmetrical Hpta and Hpqa ligands, trinickel metal string complexes may have several isomers. However, the pyridyl ring and the thiazolyl ring determined by X-ray diffraction are undistinguishable and a series of [Ni3(μ3-pta)4X2] (X = NCS, CN) are all disorder in crystallography. A series of (2,2)-cis form [Ni3(μ3-pqa)4(NCS)2] (X = NCS, CN) are the (2,2)-cis form without disorder in crystallography.
The magnetic results show that the trinickel metal string complexes all are antiferromagnetic compounds with the coupling constant in the range of -76.4 to -108.8 cm-1. While the Ni-Ni distances increase, the coupling constants decrease significantly.
Cyclic voltammetrical data shows that [Ni3(μ3-pta)4(NCS)2] exhibits no potential between +1.6 and -0.8 V whereas (2,2)-cis form [Ni3(μ3-pqa)4(NCS)2] exhibits one oxidative potential at +0.66 V and one reductive potential with ligands at -0.76 V.
Additionally, (4,0) form [Ni3(N-μ3-pqa)3(C-μ3-pqa)Cl](PF6) has been synthesized and characterized by various spectroscopic techniques. X-ray structural studies show that C-H activation is occurred in the complex and Ni-Ni distances are 2.407(1), 2.361(1) Å, respectively. Four quinolinyl rings of the compound are faced toward the same way ((4,0) form). One of terminal Ni2+ ions is bounded to the chloride ion as the axial ligand. IR spectra shows ν(N-H) = 3390 cm-1, ν(PF6-) = 844 cm-1. Magnetic measurement shows μeff = 2.86 B.M. at 300 K which belongs to paramagnetism of the high spin (S = 1) Ni2+ ion.
The electronic absorption spectra indicate that there are obviously different wavelengths between the (4,0) form [Ni3(N-μ3-pqa)3(C-μ3-pqa) (NCS)](PF6) and (2,2)-cis form [Ni3(μ3-pqa)4(NCS)2].
Subjects
鎳
二吡
啶胺
噻
唑
奎林
活化
異構物
分子金屬導線
nickel
dipyridyl amine
thiazole
quinoline
activation
isomer
molecular metal wire
Type
thesis
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