三吡啶二胺(H2tpda)之四核釕與混釕鎳異金屬串錯合物之合成與研究

Abstract

本篇論文主要討論五核異金屬串錯合物，以三吡啶二胺(Tripyridyldiamine)作為配基合成混釕鎳異金屬串，本實驗室於2014年發表第一個五核異金屬串錯合物[NiRu2Ni2(tpda)4(NCS)2]具有特別的負微分電阻效應。異金屬串由於導入兩種不同的金屬離子，造成金屬串的物理/化學性質改變，產生許多有趣的性質值得探討。而本論文主要研究於五核異金屬串錯合物[NiRu4(tpda)4(NCS)2](PF6)以及四核釕金屬串錯合物(2,2)-trans-[Ru4(tpda)4](BF4)，使用傳統的三吡啶二胺配基(H2tpda)，與雙核的釕起始物在絕氧的氬氣環境下加鹼萘燒反應後，再引入醋酸鎳金屬鹽，之後再加入LiCl或NaNCS置換軸向配基，再分別經由管柱層析純化，可以得到四核釕金屬串錯合物(2,2)-trans-[Ru4(tpda)4](BF4)、五核異金屬串錯合物[NiRu4(tpda)4(NCS)2](PF6)。利用X-Ray單晶繞射技術對金屬串錯合物結構作鑑定，以及磁性、電化學、IR、UV/Vis、單分子導電值等物理及化學性質測量。 由X-ray單晶繞射可得知，四核釕金屬串皆是由四片三吡啶二胺配基以(2,2)-trans錯位螺旋方式纏繞在釕金屬離子外圍，(2,2)-trans-[Ru4(tpda)4](BF4)為第一個直線型四核釕金屬串，具有一個陰離子(BF4-)，金屬串分子為九價正電荷。Ru(1)-Ru(2)鍵長為2.2808(5)Å，Ru(2)-Ru(3)鍵長為2.2749(5)Å，Ru(3)-Ru(4)鍵長為2.2468(5)Å皆具有金屬鍵結。配基末端的吡啶上的氮(N5、N6)與釕金屬(Ru1、Ru4)有配位。[NiRu4(tpda)4(NCS)2](PF6)經由X-ray單晶繞射可以得到結構，分子中的配基具有左旋(left-handed)、右旋(right-handed)失序的現象，金屬串末端(terminal)金屬也具有失序的現象，分別為50%的鎳金屬，50%的釕金屬。藉由磁性分析得知在300K時的有效磁矩為3.67(B.M.)，偶合常數為J= - 44 cm-1。電化學研究上，以循環伏安法研究其氧化還原電位，總共有六個氧化還原對，四個在正電位的部分，兩個在負電位的部分。分別為E1/2ox1= +0.079V、E1/2ox2= +0.579V、E1/2ox3= +0.936V、E1/2ox4= +1.256V、E1/2red1= -0.620V、E1/2red2= -1.656V。導電值部分測量以STM-bj方法測量導電值，測得單分子導電值為4.05 x 10-5 G0。 另外一部分為利用修飾配基方式合成出修飾苯基三核喹啉配基去合成鎳金屬串，成功地得到(2,2)-cis-[Ni3(phpqa)4(NCS)2]，與未修飾苯基的(2,2)-cis-[Ni3(pqa)4(NCS)2]構型相同，而且配位方式與鍵長十分相似。磁性分析結果在300K時的有效磁矩為3.96 (B.M.)，推測為兩個末端鎳金屬離子為高自旋組態 (S=1)，中間的鎳金屬離子為低自旋組態 (S=0)，理論有效磁矩4 (B.M.)，以理論擬合得到偶合常數為J= - 88 cm-1。

A pentanuclear extended metal atom chains (EMACs) complex with two different metal ions call heteronuclear metal strings (HMSCs). Our group have published [NiRu2Ni2(tpda)4(NCS)2] with first pentanuclear heteronuclear metal strings complex which exhibits NDR effect. The combination of different metal ion to synthesize metal strings give a great expectation for future micro-elecronic decive. By tunning experimental condition,We have synthesized (2,2)-trans-[Ru4(tpda)4](BF4)、[NiRu4(tpda)4(NCS)2](PF6) complexes and characterized by using X-ray diffraction, IR, UV/Vis spectroscopy and magnetism. Due to heteronuclear metal strings complexes have different metal behavior in physical/chemistry propertys,We have measured the conductivity of [NiRu4(tpda)4(NCS)2](PF6) complex in order to compare with [NiRu2Ni2(tpda)4(NCS)2] and other homonuclear metal strings complexes. First part,We have successful synthesized (2,2)-trans-[Ru4(tpda)4](BF4) and we characterized by ESI-MS, X-ray single crystal diffraction. The crystal structure of (2,2)-trans-[Ru4(tpda)4](BF4) exhibit four ligands are transposition as (2,2)-trans comformation, and all ligands are binding four ruthenium ions. Bond lengths of Ru-Ru between 2.2468(5) Å and 2.2808(5) Å. There are two adjacent ligands which terminal pyridine (N5,N6) coordinated with terminal ruthenium (Ru1,Ru4). [NiRu4(tpda)4(NCS)2](PF6) have successful synthesized and characterized by ESI-MS and X-ray single crystal diffraction. The crystal structure have ligand disorder problem(left-/right- handed), and both terminal metal ions have disorder (50% Ni, 50% Ru). Four ligand binding five metal ions in linear mode. The magnetic measurement of complex is antiferromagnetic interaction ( J= - 44 cm-1),and the μeff value of 3.67μB at 300K,We can predict it have two magnetic centers (S=1,1/2),and the expermental value very close to theory value (μeff=3.31). According to cyclic voltammograms, [NiRu4(tpda)4(NCS)2](PF6) exhibit four oxidation waves at E1/2ox1 = +0.079 V、E1/2ox2 = +0.579 V、E1/2ox3 = +0.936 V、E1/2ox4 = +1.256 V and two reduction waves at E1/2red1 = -0.620 V、E1/2red2 = -1.656 V. Finally we measure the conductivity by STM-bj method, [NiRu4(tpda)4(NCS)2](PF6) have 4.05 x 10-5 G0 conductive value which is two order smalller than other metal string. Second part is Modificaton of phenyl group with quinoline and ligand is successful synthesized and characterized by 1H-NMR, ESI-MS. (2,2)-cis-[Ni3(phpqa)4(NCS)2] have successful synthesized and characterized by ESI-MS and X-ray single crystal diffraction. Four ligands are binding three nickel metal ions as linear type, and the (2,2)-cis comformation is comfirmed by X-ray diffraction. It is very similar bond length and comformation to non-modified phenyl group quinoline’s metal strings (2,2)-cis-[Ni3(pqa)4(NCS)2]. According to magnetic measurement , it exhibit antiferromagnetic interaction (J = - 88cm-1), and the μeff value of 3.96μB at 300K,We can predict it have three magnetic centers (S=1,0,1), and the expermental value very close to theory value (μeff=4 B.M.).