萘啶吡啶胺剛性配基及其直線型四核鎳金屬串錯合物之合成與研究

Abstract

對於合成更長鏈的金屬串錯合物，多吡啶胺配基會以syn或anti方式來與金屬作配位，影響著金屬串錯合物的產率高低和副產物多寡，設計將配基只能以syn配位方式來反應，用來解決在多核金屬串錯合物會發生的低產率和多副產物之現象。本論文研究目的為合成不對稱剛性四氮配基(Htzbp)及其金屬串錯合物，並與本實驗室王瑞仁學長合成出一系列四氮配基(Hpyany, Hpzany, Hpcany)及其金屬串錯合物做比較和討論。 將Hpyany的萘啶環和吡啶環以氧鍵結，形成一剛性的新型配基。透過硝化反應、氯化反應及cross coupling，合成出Htzbp (1,2,11-triazabenzo[b]phenoxazine)。將此單晶結構與其他不對稱四氮配基單晶做比較。 利用本實驗室獨特的萘燒法，在高溫220 oC下與金屬反應，形成一含四片配基且直線型金屬串錯合物。不對稱配基合成出的金屬串可能具有四種形式，分別為(4,0)、(3,1)、(2,2-cis)及(2,2-trans)，將配基修飾一立體障礙較大的官能基，可控制其金屬串錯合物為(4,0)的配位形式。而Htzbp不具有立體障礙的官能基，因此可能具有四種形式的金屬串錯合物。 [Ni4(tzbp)4(NCS)2](NCS) (2)的X-ray單晶繞射分析，四個配基雖然有失序的情況，但Ni(1)-Ni(2) = 2.4063(9) Å、Ni(2)-Ni(3) = 2.4078(9) Å、Ni(3)-Ni(4) = 2.4300(9) Å，為一個不對稱的鍵長長度；藉由電化學可以發現僅有一組可逆氧化還原電位的訊號；磁性分析上，萘啶單元[Ni2]3+電子組態為S = 3/2，Ni(4)為為獨立之高自旋d8電子組態S = 1；可推斷其為(4,0)[Ni4(tzbp)4(NCS)2](NCS)四核鎳金屬串錯合物。

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.