| Summary: | 碩士 === 國立臺灣大學 === 化學研究所 === 103 === In order to avoid the potential problem of several side products for synthesizing longer metal strings, the syn mode plays a crucial role. Our lab had been successfully synthesized Hdzp ligand (1,9-diazaphenoxazine), which limited the syn coordination mode of oligo-α-pyridylamine ligands by binding their pyridine rings. Here we present the design and preparation of new unsymmetrical tetra-dentate ligand, Htzbp (1,2,11-triazabenzo[b]phenoxazine), which is rigid by binding 1,8-napthyridine and pyridine ring, and the studies of their tetra-nickel string complexes.
A new ligand, 1,2,11-triazabenzo[b]phenoxazine (Htzbp), is synthesized by nitrification, chlorination and the cross-coupling of 2-chloro-3-nitro-1,8-naphthyridine with 2-amnio-3-hydroxypyridine. The single crystal of Htzbp is studied.
The linear tetra-nickel string complexes are synthesized through reacting of ligand with Ni(OAc)2‧4H2O. Because of the unsymmetrical ligand , there are four possible geometrical isomers of the tetra-nickel string complexes from the orientations of the ligands, abbreviated as (4,0), (3,1), (2,2-cis) and (2,2-trans) forms. Lack of the steric hindrance of the bulky functional group, [Ni4(tzbp)4(NCS)2](NCS) (2) could be one of four geometric isomers.
From the experimental results of X-ray crystallography, the four sets of ligand have the disorder situation, we find out that Ni(1)-Ni(2) = 2.4063(9) Å, Ni(2)-Ni(3) = 2.4078(9) Å and Ni(3)-Ni(4) = 2.4300(9) Å are unsymmetrical Ni-Ni bond length. The electrochemical study shows that there is only one set reversible signal, E1/2(oxi) = +0.2683 V and E1/2(red) = -0.1720 V. The magnetism of linear tetra-nickel string complex is studied, after one electron reduction that occurred in the two nickel atoms at the position of naphthyridine rings, the spin state of the two nickel atom is S = 3/2. As the results of those, we suggest that (4,0)[Ni4(tzbp)4(NCS)2](NCS) is obtained.
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