直線型三核、五核釕金屬錯合物之合成及研究

Syntheses and Studies of the Linear Tri- and Pentanuclear Ruthenium Complexes

郭敬國(Ching-Kuo Kuo)

指導教授 ： 彭旭明

國立臺灣大學/理學院/化學研究所/博士(2006年)

https://doi.org/10.6342/NTU.2006.00154

摘要

我們以多吡啶胺配基(oligo-α-pyridylamino ligands)為主，成功合成出直線型三核、五核釕金屬錯合物。在本論文中，主要的研究主題有三項：(一)藉由三核釕金屬錯合物的氧化差異性，深入地探討此類錯合物的金屬-金屬間作用；(二)軸向配基被置換成含氧化-還原活性的二戊鐵基團(Fc)，電化學結果顯示其三核釕金屬錯合物有電子傳遞的現象；另一方面，軸向配基被置換成不同推、拉電子性質之基團，亦探討其推、拉電子效應對其錯合物核心電子密度的影響；(三)我們亦成功合成出直線型五核釕金屬錯合物及直線型五核鎳、釕異金屬錯合物並得到單晶結構。
本論文的成果概括如下：中性、一個電子氧化、兩個電子氧化的直線型三核釕金屬錯合物[Ru3(μ3-dpa)4Cl2](BF4) (1B)、[Ru3(μ3-dpa)4Cl2](BF4)2 (1C)、[Ru3(μ3-dpa)4(CN)2] (1D)、[Ru3(μ3-dpa)4(CN)2](BF4) (1E) (dpa = the anion of dipyridylamine)被合成出來且藉由各種光譜技術鑑定其特性。循環伏安法(Cyclic voltammetry)及光譜電化學研究結果得知這一系列錯合物為Ru3核心上發生三個連續的一個電子轉移。X-射線結構研究顯示這系列錯合物的Ru3核心是對稱；隨著中性錯合物被氧化，金屬間的鍵長只有稍微的變化而金屬-軸向配基的長度卻明顯的變小。當氯離子軸向配基被置換成較強的”π-acid”氰根配基，其Ru3本身的電子組態亦會改變。磁性、1H NMR圖譜可得到[Ru3(μ3-dpa)4Cl2]、[Ru3(μ3-dpa)4Cl2](BF4)2總自旋電子數分別為S = 0；[Ru3(μ3-dpa)4Cl2](BF4)、[Ru3(μ3-dpa)4(CN)2]、[Ru3(μ3-dpa)4(CN)2](BF4)總自旋電子數分別為 S = 1/2、1、3/2。這些結果與理論計算相符。
一系列含炔基取代基的三核釕金屬錯合物[Ru3(μ3-dpa)4(C2X)2](BF4)y (X = Fc, y = 0 (2A); X = Ph, y = 0 (2B); X =
PhOCH3, y = 1 (2C); X = PhC5H11, y = 1 (2D); X = PhCN, y = 0 (2E); X= PhNO2, y = 0 (2F) )亦被合成出。晶體結構顯示這些錯合物的Ru-Ru鍵長(2.3304(9)-2.3572(5) Å)比[Ru3(μ3-dpa)4Cl2] (Ru-Ru=2.2537(1) Å)的鍵長較長；這是因為形成較強的金屬對軸向配基之π-backbonding而減弱Ru-Ru的作用且Ru3本身的鍵序亦降低了。循環伏安法(Cyclicvoltammetry)和差式脈衝伏安法(differential pulse voltammetry)顯示錯合物2A的兩個Fc基團之間的電子傳遞其ΔE1/2 ~ 100 mV，顯示有弱電子偶合現象。錯合物2B-2F顯示了三個可逆氧化-還原峰：兩個氧化、一個還原，而電極電位會隨著不同取代基而改變，Hammett常數對電極電位做圖可以得到線性關係。

第一個以第二週期過渡金屬為主的直線型五核金屬錯合物
[Ru5(μ5-tpda)4Cl2]+[(Ru2(μ-OAc)4)2Cl3]- (3A) (tpda = the dianion of N,N'-bis(α-pyridyl)-2,6-diaminopyridine)被合成出來；含鎳、釕的直線型五核異金屬錯合物[Ni3Ru2(μ5-tpda)4(NCS)2] (3B) 、[Ni3Ru2(μ5-tpda)4(NCS)2](BF4) (3C)亦被合成出來。在錯合物3A中，
Ru(1)-Ru(2) 、Ru(2)-Ru(3) 的鍵長分別為2.2922(8) 、2.2832(6)Å ；Ru(1)-Ru(2)-Ru(3)、Ru(2)-Ru(3)-Ru(2A) 的鍵角分別為178.77(3)、
180.00(3)°。因為錯合物中電荷平衡影響及再結晶中需要適當的堆疊
大小，所以伴隨著直線型的相對陰離子形成。錯合物3C可由錯合物3B加入適當的氧化劑而得到，由一些的鑑定方法(IR、電子吸收光譜、電化學、光譜電化學)可以確認出錯合物3C的存在。

關鍵字

分子導線 ； 釕 ； 推拉電子 ； 氧化

並列摘要

The syntheses of oligo-α-pyridylamino ligands and their linear trinuclear and pentanuclear ruthenium complexes are reported. This thesis concerns in three aspects: First, owing to difference of oxidation of trinuclear ruthenium complexes, metal-metal interaction of these complexes are studied carefully. Second, while the axial ligands of triruthenium complex are replaced by redox-active ferrocenyl (Fc) groups, electrochemical results reveal that there is electronic communication within the triruthenium complex. Then, the electronic effect is investigated by varying the axial ligands of triruthenium complexes. The effects of donor/acceptor modifications in electrochemistry are also investigated. Third, the linear pentanuclear ruthenium complex and linear pentanuclear mixed-metal (Ni2+ and Ru2+) complexes have been synthesized and characterized by X-ray analysis.
The results are summarized as follows: The neutral, one-, and two-electron oxidized linear trinuclear ruthenium complexes [Ru3(μ3-dpa)4Cl2](BF4), [Ru3(μ3-dpa)4Cl2](BF4)2, [Ru3(μ3-dpa)4(CN)2], and [Ru3(μ3-dpa)4(CN)2](BF4) (dpa = the anion of dipyridylamine) have been synthesized and characterized by various spectroscopic techniques. Cyclic voltammetric and spectroelectrochemical studies on the neutral and oxidized complexes are reported. These complexes undergo three successive metal centered one electron transfer processes. X-ray structural studies reveal a symmetrical Ru3 unit for these complexes. While the metal–metal bond distances only slightly change, the metal–axial ligand lengths exhibit a significant decrease upon oxidation of the neutral complex. The electronic configuration of Ru3 unit changes as the chloride axial ligands are replaced by the stronger “π-acid” cyanide
axial ligands. Magnetic measurements and 1H NMR spectra indicate that[Ru3(μ3-dpa)4Cl2] and [Ru3(μ3-dpa)4Cl2](BF4)2 are in a spin state of S = 0 and [Ru3(μ3-dpa)4Cl2](BF4), [Ru3(μ3-dpa)4(CN)2], and [Ru3(μ3-dpa)4(CN)2](BF4) in spin states of S = 1/2, 1, and 3/2, respectively. These results are consistent with M.O. calculations. A series of triruthenium complexes with arylacetylide axial ligands
[Ru3(μ3-dpa)4(C2X)2](BF4)y (X = Fc, y = 0 (2A); X = Ph, y = 0 (2B); X = PhOCH3, y = 1 (2C); X = PhC5H11, y = 1 (2D); X = PhCN, y = 0 (2E); X = PhNO2, y = 0 (2F) ) have been synthesized. The crystal structures show that the Ru-Ru bond lengths (2.3304(9)-2.3572(5) Å) of these compounds
are longer than those of [Ru3(μ3-dpa)4Cl2] (Ru-Ru=2.2537(1) Å). This is ascribed to the formation of the stronger π-backbonding from metal to axial ligand weakens the Ru-Ru interactions and a bond order is reduced in the triruthenium unit. Cyclic voltammetry and differential pulse
voltammetry show that compound 2A exhibits electronic coupling between the two ferrocenyl units with ΔE1/2 close to 100 mV. Compounds 2B-2F display three triruthenium-based reversible one-electron redox couples, two oxidations and one reduction, and the electrode potentials shift upon varying substituents. A linear relationship is observed when the Hammett constants are plotted against the redox potentials.
The first linear pentanuclear metal complex with the second-row transition metal, [Ru5(μ5-tpda)4Cl2]+[(Ru2(μ-OAc)4)2Cl3]- (3A) (tpda = the dianion of N,N'-bis(α-pyridyl)-2,6-diaminopyridine), has been synthesized. The linear penta-nuclear mixed-metal complexes with nickel and ruthenium, [Ni3Ru2(μ5-tpda)4(NCS)2] (3B) and [Ni3Ru2(μ5-tpda)4(NCS)2](BF4) (3C), have also been synthesized. In complex 3A, The bond lengths of Ru(1)-Ru(2) and Ru(2)-Ru(3) are 2.2922(8)Å and 2.2832(6)Å, respectively. The bond angles of Ru(1)-Ru(2)-Ru(3) and Ru(2)-Ru(3)-Ru(2A) are 178.77(3)° and 180.00(3)°, respectively. The linear counter anion has been formed owing to the charge balance of the complex and suitable packing size during recrystallization. Complex 3C was obtained by adding suitable oxidizing reagent in complex 3B. According to some identification (IR, electronic
absorption spectrum, electrochemistry, and OTTLE), we can ensure the existence of complex 3C.

並列關鍵字

molecular wire ； ruthenium ； electron donor/acceptor ； oxidation

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