修飾不對稱吡啶萘啶二胺配基及其鎳金屬串與金屬簇之合成與研究

Syntheses and Characterization of Metal Strings and Cluster Complexes with the Modified Asymmetrical Ligands

戴品仁(Pin-Ren Dai)

指導教授 ： 彭旭明

國立臺灣大學/理學院/化學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.03346

摘要

本論文研究內容為新型不對稱H2pan(2-pyridylamino-7- acetylamino-1,8-naphthyridine)與H2ppan(2-(5-phenylpyridyl)amino-7- acetylamino-1,8-naphthyridine)配基之五核鎳金屬串錯合物、四核鈷、銅和鋅金屬簇錯合物之合成、結構分析、磁性及其電化學之探討。
此新型不對稱配基可由S. L. Buchwald27所提出的鈀金屬鹽類催化反應而得到，並經由NMR、FAB質譜鑑定證實得到產物。首先將合成出的H2pan與H2ppan配基分別和過量Ni(OAc)2．4H2O進行高溫萘燒反應，依序可得到新型五核金屬串錯合物[Ni5(pan)4(OAc)2]與[Ni5(ppan)4Cl2]，由X-ray單晶繞射解析,其錯合物[Ni5(pan)4(OAc)2]之晶系為三斜晶系，空間群為P-1，非對稱單元為壹個分子，其電中性錯合物[Ni5(pan)4(OAc)2]的主體結構是由五個Ni2+經由四個pan2-配基螺旋纏繞配位，另有兩個醋酸根陰離子配位形成。在Ni2+配位環境中，Ni (4)和Ni (5)皆為八面體配位環境，主要是由一個鉗合的醋酸根陰離子、乙醯基團上的氧、另一個配基的鉗合萘啶胺及另一cis位置配基上吡啶配位組成；而Ni (1)和Ni (3)為扭曲四角錐配位環境，各自由四個配基上兩個萘啶、一個吡啶及一個胺配位所組成，其中特別的是Ni (1)和Ni (4)、Ni (3)和Ni (5)之間是由乙醯基的氧當作橋基連結；Ni (2)為方型平面配位環境，各自由四個配基上兩個萘啶及兩個胺所組成。相對於本實驗室傳統金屬串而言，此錯合物的中間三核部份與傳統直線三核金屬串相似，兩端另連結六配位高自旋Ni2+，三核金屬串及金屬串與末端鎳離子平均金屬間距離為2.414及3.30 A，而經由Ni-N之鍵長，可知Ni(2)為低自旋電子組態，其餘為高自旋電子組態。
在磁性量測結果，錯合物[Ni5(pan)4(OAc)2]為反鐵磁性，在室溫下其μ值為5.14 B.M，隨者溫度下降其μ值亦降低，到50K時為4.16 B.M.，根據X-ray單晶繞射分析，其電子組態由一個低自旋Ni2+及四個高自旋Ni2+組成，理論值為5.65 B.M.，與實驗結果相比較，推測其差距應為錯合物[Ni5(pan)4(OAc)2]具有強反鐵磁作用力，因此在室溫下未達理論最大值。另由循環伏安法得知[Ni5(pan)4(OAc)2]在-0.78 V有一對可逆氧化還原峰。
而錯合物[Ni5(ppan)4Cl2]之晶系為單斜晶系，空間群為P21/c，非對稱單元為整個分子，其主體結構為與錯合物[Ni5(pan)4(OAc)2]相似，主要差別為最外側Ni2+配位環境是扭曲四角錐配位。磁性量測結果，錯合物[Ni5(ppan)4Cl2]為反鐵磁性，室溫下其μ值為5.01 B.M.，隨者溫度下降其μ值亦降低，到50 K時為4.26 B.M.，其結果與錯合物[Ni5(pan)4(OAc)2]相似。
最後利用H2pan配基分別與鈷、銅和鋅金屬鹽類進行配位化學研究，可得到四核的金屬簇錯合物，其中銅與鋅金屬所生成金屬簇皆為[2×2]結構，並在配基上發生不預期氧化反應，探討其結構、磁性性質。

關鍵字

鎳金屬串 ； 配位化學 ； 金屬簇

並列摘要

The aim of this research is to investigate the synthesis, structure, and properties of the pentanickel metal string complexes and the tetranuclear cluster which the ligands are 2-pyridylamino-7-acetylamino- 1,8-naphthyridine (H2pan) and 2-(5-phenylpyridyl) -amino-7-acetylamino-1,8-naphthyridine(H2ppan).
The novel asymmetrical ligands were synthesized by palladium-catalyzed reaction which was proposed by S. L. Buchwald27, and the product was characterized by NMR and FAB-MS.
First of all, we reacted these ligands with Ni(OAc)2．4H2O at high temperature of melt naphthalene, we successfully obtained two novel pentanickel metal string compounds, [Ni5(pan)4(OAc)2] and [Ni5(ppan)4Cl2]. The X-ray structure studies of [Ni5(pan)4(OAc)2] reveals the crystal system is triclinic and the space group is P-1. In the structure of [Ni5(pan)4(OAc)2], the terminal nickel ions (Ni5, Ni4) are octahedral. In the metal string, the outer nickel ions (Ni1, Ni3) are square pyramidal and the central nickel ion (Ni2) is square planar. The axial ligand is acetate ion. There are two forms for ligands binding: one uses the nitrogen atom from amide group to bind terminal nickel ions, and another uses oxygen atom from amide to connect with two outer nickel ions as a bridge. Compared to traditional metal string, the middle part of this complex is similar to trinickel string complexes. The average metal distance from inside to outside is 2.414 and 3.30 A. Through the bond length of Ni-N, we know that Ni(2) is LS, and other Nickel ions are HS. The magnetic properties shows that the pentanickel complex [Ni5(pan)4(OAc)2] is antiferromagnetic. The μeff value for [Ni5(pan)4(OAc)2] is 5.16 B.M at 300K. The CV of [Ni5(pan)4(OAc)2] complex show one reversible reduction at -0.78 V.
The structure of [Ni5(ppan)4Cl2] is monoclinic, and the space group is P21/c. The major structure is similar to that of [Ni5(pan)4(OAc)2]. The main difference is that the outer nickel ions are square pyramidal. The magnetic properties show that the pentanickel complex [Ni5(ppan)4Cl2] is antiferromagnetic. The μeff for [Ni5(ppan)4Cl2] is 5.01 B.M at 300 K. The CV of [Ni5(ppan)4Cl2], one reversible reduction at -0.70 V for [Ni5(ppan)4Cl2].
Eventually, we study the coordination chemistry by using H2pan ligand to react separately with cobalt, copper and zinc ions to get tetranuclear clusters; among this, copper and zinc metal clusters all formed [2×2] structure. We also study its structure and magnetic properties.

並列關鍵字

Nickel Metal String ； Coordination chemistry ； Metal Cluster

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