混配基三核鎳金屬串幾何異構物之合成與研究

Abstract

本論文研究內容是以苯醯胺基吡啶二胺（H2pdaBz2）與二吡啶胺（Hdpa）之混配基三核鎳金屬串錯合物之合成、結構分析、磁性、電化學之探討。 在高溫萘燒反應條件下，H2pdaBz2配基和Hdpa配基得到混配基三核鎳金屬串錯合物[Ni3(dpa)2(pdaBz2)2]，並成功地以管柱層析分離出兩種異構物。 由X-Ray單晶繞射解析儀可知，[Ni3(dpa)2(pdaBz2)2]兩種異構物分別為[trans-Ni3(dpa)2(pdaBz2)2] (1a)和[cis-Ni3(dpa)2(pdaBz2)2] (1b)。其中之一為兩片相同的配基（dpa）為鄰位，另一為兩片相同的配基（dpa）為對位。兩種幾何異構物，中間鎳離子的鎳-氮距離約為1.9Å，此距離與文獻中低自旋組態之鎳-氮距離相符，而兩端鎳離子因具軸向配基，造成具軸向配基相接之鎳離子之配位環境為四方錐形式，而其鎳-氮距離大約為2.1Å，此距離與文獻中高自旋組態之鎳-氮距離相符。磁性結果也顯示出兩端鎳離子為高自旋電子組態，中間鎳離子為低自旋電子組態。 磁性結果得知，此兩錯合物皆為反鐵磁作用力，在300K時，μeff值分別為2.893 B.M.及2.635 B.M.，偶合常數J13值分別為 -107 cm-1及 -100 cm-1。 在電化學上，由循環伏安法可得知，兩種幾合異構物在還原電位的部分均存在一對可逆之氧化還原電位分別為E1/2(Red) = -0.9585V (1a)及E1/2(Red) = -0.9685V (1b)。

The aim of this thesis is to investigate the synthesis, structures and properties of the mixed ligand tri-nickel complexes, where the ligands are dipyridylamine (Hdpa), 2,6-Bis(benzoylamino)pyridine(H2pdaBz2). The mixed ligand tri-nickel complexes, [Ni3(dpa)2(pdaBz2)2], can be synthesized at high temperature by using naphthalene as the solvent. The X-Ray structures show that there are two geometric isomers . They are named [(2,2)-trans-Ni3(dpa)2(pdaBz2)2] (1a) and [(2,2)-cis-Ni3(dpa)2(pdaBz2)2] (1b). One is that two identical ligands(dpa) are ortho, the other is that two identical ligands(dpa) are para. Both two isomers show that the middle Ni(Ⅱ) ion displayed short Ni-N(~1.9Å) bond distances which are consistent with a low spin state of Ni(Ⅱ) ions. The terminal Ni(Ⅱ) ions bonded with axial ligands are in square-pyramidal (NiN4X) environment and exhibit long Ni-N bond distance(~2.1Å) which are consistent with a high spin Ni(Ⅱ) configuration. The magnetic measurements show that the terminal Ni(Ⅱ) ions are high spin configuration, the middle Ni(Ⅱ) ion are low spin configuration. The magnetic susceptibility shows that both two complexes are antiferromagnetic interaction. The μeff value for two complexes are 2.893 B.M. and 2.635 B.M. respectively at 300K. And the coupling constant J13 are -107 cm-1and -100 cm-1 . According to the cycling voltammograms , both two complexs exhibit one reduction waves at-0.9585V (1a) and -0.9685V.