直線型金屬串的合成與研究： 三核、九核和十三核金屬串錯合物，最長金屬串錯合物的探究

Syntheses and Studies of the Extended Metal Atom Chains: from Tri- to Trideca-Nuclear Metal String Complexes, a Great Adventure to Develop the Longest Metal String Complexes

楊景鈞(Ching-Chun Yang)

指導教授 ： 彭旭明

國立臺灣大學/理學院/化學研究所/博士(2014年)

https://doi.org/10.6342/NTU.2014.00273

摘要

本論文主要分成兩個主要部分，第一個部分是克服三核金屬串晶體排列失序為目標，利用修飾官能基的方式在吡啶的4號位修飾一個甲基分子，進行其三核金屬串的合成與研究。第二個部分是以增長金屬串為目標，以鉑催化進行cross-coupling合成出九氮、十三氮和十七氮配基，並進行超長金屬串:九核鎳、九核鈷、十三核鎳金屬串和十七核鎳金屬串錯合物的合成與性質量測。
利用不對稱型三氮配基(Hpta)合成出來的三核鎳金屬串[Ni3(pta)4X2] (X = NCS- (1), CN- (2))會有分子結構失序的問題。為了克服失序的問題，首先在吡啶4號位修飾上一個甲基分子形成一新型的不對稱三氮配基4-甲基吡啶噻唑胺(Hmpta)配基，增加不對稱形配基兩邊結構上的差異性，成功的得到具有2,2-cis form的三核金屬串錯合物[Ni3(mpta)4X2] (X = NCS- (3), CN- (4))，並且進一步進行性質的量測，從導電度的結果得知，具有弱場軸向配基的[Ni3(mpta)4(NCS)2] (3)其導電度高於具有強場配基[Ni3(mpta)4(CN)2] (4)約57 %。
新型的九氮配基H3Ph2N9，主要以雙萘啶胺為主體並在末端兩側吡啶的對位修飾上苯環，苯環是一個具有推電子能力且較龐大的取代基，期望可以提高金屬串的溶解度、產率以及結晶性，利用此九氮配基成功的得到正四價的九核鎳金屬串分子[Ni9(Ph2N9)4X2](BF4)4 (X = Cl- (5), NCS- (6))和帶有正二價的九核鈷金屬串分子[Co9(Ph2N9)4Cl2](BF4)2 (7)與[Co9(Ph2N9)4(NCS)2(BF4)1.5Cl0.5 (8)。在九核鎳金屬串部分，正四價九核鎳金屬串錯合物中的九個鎳金屬皆為正二價離子，末端鎳金屬為高自旋態，S = 1，其他鎳金屬皆為低自旋態，S = 0。電化學實驗結果顯示九核鎳金屬串分子[Ni9(Ph2N9)4Cl2](BF4)4在氧化部分有一對可逆的氧化還原對E1/2 = +0.94 V，還原部分有三對可逆的氧化還原對分別為E1/2 = +0.12 V、E1/2 = -0.09 V 與E1/2 = -0.41 V。在九核鈷金屬串部分Co1到Co9的長度約為18.25 A左右，鈷金屬之間具有fully delocalized的金屬-金屬鍵結，是目前文獻上最長的鈷金屬串，也是具有最長的fully delocalized金屬-金屬鍵結的錯合物。
新型的十三氮配基H5tpdnpa，主體以雙萘啶胺為主體並在兩邊分別延伸二吡啶二胺，形成一對稱四吡啶二萘啶五胺的新型十三氮配基，利用此十三氮配基成功合成帶有正二價的十三核鎳金屬串[Ni13(tpdnpa)4Cl2](PF6)2 (9)，兩個電子還原在中間兩個萘啶單元上形成混價的[Ni2]3+單元。正二價十三核鎳金屬串錯合物中，Ni1到Ni1A的長度約為27.28 A左右，這是目前文獻上最長的鎳金屬串。在磁性上，末端鎳金屬為高自旋態，S = 1，在萘啶官能基的[Ni2]3+單元中，電子透過兩金屬之間的σ軌域產生部份的非定域化，使Ni－Ni 的鍵長縮短，其他鎳金屬皆為低自旋態，S = 0。將電子組態簡化為四核金屬錯合物的模型並且進行擬合，從擬合的結果(J12 = J34 = -20.24 cm-1、 J23 = -284.22 cm-1)得知整個反鐵磁貢獻在中間兩個萘啶單元上。經由電化學分析，[Ni13(tpdnpa)4Cl2](PF6)2 (9)有三對可逆的氧化還原反應，氧化部分有一對可逆的氧化還原對E1/2 = +0.60 V，還原部分有兩對可逆的氧化還原對分別為E1/2 = -0.07 V與E1/2 = -0.64V。經由比表面積氮氣吸附的實驗，[Ni13(tpdnpa)4Cl2](PF6)2 (9)在77 K一大氣壓下對於氮氣分子的吸附量約23 cm3/g其BET比表面積為28.2 m2/g，並且經由TGA溶劑循環吸脫附實驗發現證明此十三核鎳金屬串錯合物具有dichloromethane、1,2-dichloroethane和benzene分子的吸脫附特性。
新型的十七氮配基H7hpdnha，主體以雙萘啶胺為主體並在兩邊分別延伸三吡啶三胺，形成一對稱六吡啶二萘啶七胺的新型十七氮配基，利用此十七氮配基成功合成帶有正四價的十七核鎳金屬串[Ni17(hpdnha)4Cl2](PF6)4 (10)，很可惜的是我們並沒有得到良好的單晶，進行X-ray單晶繞射的實驗，我們只能利用質譜儀來證明十七核鎳金屬串分子已經成功的合成([M+]= 4343)，目前養晶的工作仍持續進行中。

關鍵字

金屬串 ； 磁性 ； 電化學 ； 導電度

並列摘要

This thesis concerns in two aspects: First, to overcome crystal disorder arranged in the trinuclear metal strings as the goal. We modified a methyl group on tridentate ligand, and synthesized their linear trinuclear metal strings. Second, intends to synthesize such very long and develop novel applications EMACs are our research purposes. We synthesized three new mix pyridyl-naphthyridyl-amine ligand, bis(N-5-phenylpyridin-2-yl-2-amino-1,8-naphthyridin-7-yl)amine (H3Ph2N9) , N2-(6-(pyridin-2-ylamino)pyridin-2-yl)-N7-(7-(6-(pyridin-2-ylamino)pyridin- 2-ylamino)-1,8-naphthyridin-2-yl)-1,8-naphthyridine-2,7-diamine (H5tpdnpa) and hexapyridyldinapthridylheptaamine (H7hpdnha), and their EMACs.
Asymmetric tridentate ligand (Hpta) synthesized two trinuclear nickel strings [Ni3(pta)4X2] (X = NCS-(1), CN-(2)), accompanying with the molecular structure arranged disorder problem, which means that can not distinguish between thiazolyl group and pyridyl group in the crystal structure. To overcome this problem, we synthesized a new tridentate ligand (Hmpta) by substituting picolyl group for the pyridyl group, in order to increase asymmetrical differences in both sides. By this strategy, we successfully synthesized two trinuclear nickel strings [Ni3(mpta)4X2] (X = NCS-(3), CN-(4)) in (2,2)-cis arrangement.The conductance and resistance for single molecules of 3 are 1.8 (±0.4) × 10–3 G0 and 7.1 (±1.5) MΩ, respectively, compared to 1.2 (±0.4)×10–3 G0 and 11.1 (±3.9) MΩ for 4. The conductivity of 3 is ca. 57 % higher than that of 4, which is reflected in the different distances between nickel atoms (ca. 2.47 A for 3, and ca. 2.52 A for 4).
Nonanuclear nickel and cobalt string complexes are synthesized with H3Ph2N9 ligand. In nickel system, the electrochemistry of Ni9 complexes displays four redox couples at E1/2(red1) = ＋0.12V, E1/2(red2) = －0.09 V, E1/2(red3) = －0.41 V and E1/2(ox1) = ＋0.94 V, repectively. The magnetic moment of [Ni9(Ph2N9)4Cl2](BF4)3.5Cl0.5 (5) is 4.03 μB (300K) and consistent with terminal nickel(II) ions are high-spin states (S＝1). Unfortunately, we could not get a good quality crystal of [Ni9(Ph2N9)4(NCS)2]4+ (6) for single crystal X-ray diffraction experiment. In cobalt system, the single crystal X-ray diffraction analysis reveal that two-electrons reduced in [Co9(Ph2N9)4Cl2](BF4)2 (7) and [Co9(Ph2N9)4(NCS)2](BF4)1.5Cl0.5 (8), and containing two BF4- as the counter anions in 7, one half BF4- and half Cl- in 8, respectively. The terminal chloride and nitrogen of NCS atoms are collinear with Co9 axis. The whole lengths of molecule are 23.2 A and 27.4 A for 7 and 8, respectively. These are the longest EMAC for cobalt complexes reported to date.
Tridecanickel complex [Ni13(tpdnpa)4Cl2](PF6)2 (9) was obtained by the reaction of anhydrous NiCl2 with the H5tpdnpa ligand in an argon atmosphere employing naphthalene as solvent and ButOK as a base to deprotonate the amine groups. The linear chain of tridecanickel atoms are helically wrapped by four all-syn type tpdnpa5- ligands, and the chloride atoms of the axial ligands are collinear with the tridecanickel axis; the molecular length is about 32 A. Magnetic measurement of [Ni13(tpdnpa)4Cl2]×(PF6)2 (9) reveals that antiferromagnetic interactions between the terminal Ni2+ ion and the central Ni23+ unit. The best fit above 4 K corresponds to: g= 2.3, J12 = J34 = -20.24 cm-1, J23 = -284.22 cm-1, indicative of relatively strong antiferromagnetic couplings between mixed-valence Ni23+ units, and weaker antiferromagnetic couplings between Ni2+ and mixed-valence Ni23+ unit. TGA and solvent cyclic ad/de-sorption measurements revealed a one-step weight loss of solvent molecules and reversible dichloromethane, 1,2-dichloroethane and benzene adsorption/desorption process. The N2 ad/de-sorption measurement reveals a typical Type-IV adsorption curve with an H2 hysteresis loop as defined by the IUPAC classification and is characteristic of mesoporous material. The [Ni13(tpdnpa)4Cl2]×(PF6)2 (9) is not only the longest nickel string up to date, but also the first EMAC using in porous applications.
Heptadecanickel complex [Ni17(hpdnha)4Cl2](PF6)4 (10) was obtained by the reaction of anhydrous NiCl2 with the H7hpdnha ligand in an argon atmosphere employing naphthalene as solvent and ButOK as a base to deprotonate the amine groups. Unfortunately, we can not get a good quality crystal to do X-ray diffraction experiment, but we can find it by MALDI-MASS experiment on peak [M+]= 4343.

並列關鍵字

metal string ； magnetism ； electrochemistry ； conductance

參考文獻

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