本論文利用拉曼光譜研究Ni2(TPG)4及[Ni2(TPG)4]+-BF4雙核金屬錯合物、Ni3(dpa)4(NCS)2、Ni3(dpa)4Cl2 (dpa=di-pyridyl-amindo)直線型三核金屬串錯合物與互為鏡像異構物的Δ-[Ni5((-)camnpda)4]及Λ-[Ni5((+)camnpda)4]的振動模式，以了解其中不同價數的鎳-鎳鍵結強度。我們利用He-Ne雷射(632.8 nm)為激發光源及高解析拉曼光譜系統，測量了錯合物的固態拉曼光譜、表面增強拉曼光譜 (SERS) 及電化學表面增強拉曼光譜 (ECSERS)，配合循環伏安法及電化學吸收的結果指認三核鎳金屬串錯合物中金屬的價數及拉曼譜帶進行指認。在三核鎳金屬串分子SERS中，我們將其與固態拉曼光譜比較的結果，發現光譜位置會受到金屬奈米粒子表面熱電子的影響，還原金屬串分子。Ni3(dpa)4(NCS)2、Ni3(dpa)4Cl2兩者之中心金屬價數皆為[Ni3]6+共有24個軌域電子，其電子組態為全填滿之(σ)2(π)4(δ)2(n8)(δ*)2(π*)4(σ*)2，鍵序為0，沒有找到[Ni3]之對稱振動譜帶，在金奈米粒子中還原成[Ni3]5+其對稱伸縮之頻率為242 cm-1。利用ECSERS技術，將[Ni3]5+之錯合物加電壓至+0.3 V (E(V) vs Ag/AgCl)，242 cm-1譜帶消失。電壓加至+1.1 V (E(V) vs Ag/AgCl)，在 350 cm-1處有一譜帶生成。循環伏安法結果，在+1.1 V 有一氧化還原峰，因此指認350 cm-1為[Ni3]7+之對稱伸縮振動頻率。而沒有軸向配位基之[Ni3(dpa)4]3+(PF6)3之價數為[Ni3]7+，其對稱伸縮振動頻率為355 cm-1，與有軸向配位基之位置相近。Ni2(TPG)4中鎳-鎳之鍵序為0，以AgBF4氧化後形成[Ni2(TPG)4]+-BF4，價數為[Ni2]5+，鍵序為0.5，Ni-Ni間伸縮振動頻率為322 cm-1，在Δ-[Ni5((-)camnpda)4]及Λ-[Ni5((+)camnpda)4]中Ni-Ni伸縮振動頻率被指認為327 cm-1，價數為[Ni2]3+。我們亦利用ECSERS技術研究直線金屬異核錯合物Ru2Ni(dpa)4Cl2中之Ru-Ru間伸縮振動頻率。Ru2Ni(dpa)4Cl2之固態拉曼光譜中Ru-Ru間伸縮振動頻率為327 cm-1，價數為[Ru2]5+，在SERS光譜中被金奈米粒子還原成[Ru2]4+振動頻率為312 cm-1。將其加電壓可發現327、333及337 cm-1譜帶出現並且比例變多，吾人分別指認 [Ru2]價數為+5、+5及+6。其中327 cm-1之金屬價數為[Ru2]5+Ni1+而333 cm-1則為[Ru2]5+Ni2+，此藍移現象可能為鎳從+1價氧化為+2價後，鎳與[Ru2]5+之鍵結變弱，使釕-釕鍵結增強。在本篇論文中我們成功地利用ECSERS技術觀察到金屬串錯合物在不同氧化態下之振動譜帶，將來若有其他不穩定之氧化態晶體因而無法檢測其固體粉末拉曼光譜，可以以ECSRES技術解決這個問題。

We study the bond strength of nickel-nickel bond in metal string complexes by using electrochemical surface enhanced Raman spectroscopy (ECSERS). The technique is employed by recording the SERS signal during the electrochemical processes while molecules are absorbed on an electrode surface coated with nanoparticles and applied electric potentials. Using regular electrodes, the ultraviolet-visible absorption spectra can be recorded during redox reactions. There is no Ni3 sym. stretching bandνNi3 sym. assigned in solid Raman spectra of Ni3(dpa)4(NCS)2 (dpa = di-pyridyl amindo) and Ni3(dpa)4Cl2. All the bonding and antibonding d orbitals of Ni3 are filled, thus, no metal-metal bonding in [Ni3]6+. This can be the reason that noνNi3 sym. is assigned. In gold nanoparticle (AuNP) SERS, positions of all modes are the same as those in solid except that one new band appears at 242 cm-1. We infer that complex was reduced by hot electron from AuNP upon photoexcitation. Hence, 242 cm-1 is assigned to the νNi3 sym of [Ni3]5+. In the ECSERS curves only the 240 cm-1 band disappeared at +0.3 V. When applied voltage to +1.1 V, one addition band at 351 cm-1 appeared. We assigned the new band toνNi3 sym of [Ni3]7+. In order to confirm the metal bond of [Ni3]5+ and [Ni3]7+ are localized or delocalized, we obtained the solid Raman spectra of Ni2(TPG)4-BF4, Δ-[Ni5((-)camnpda)4], and Λ-[Ni5((+)camnpda)4]. For Ni2(TPG)4-BF4, we assigned the Raman band at 322 cm-1 to Ni2+–Ni3+ stretch. For Δ-[Ni5((-)camnpda)4] and Λ-[Ni5((+)camnpda)4], we assigned the Raman band at 327 cm-1 to Ni2+–Ni1+ stretch. Based on these data we can confirm that the [Ni3]5+ and [Ni3]7+ are delocalized three metal center bonding. Besides, we also use the same technique to obtain the Ru-Ru stretching wavenumber of Ru2Ni(dpa)4Cl2. In solid Raman spectra of Ru2Ni(dpa)4Cl2, we assigned the band at 327 cm-1 for Ru3+-Ru2+ stretch. νRu-Ru in AuNP SERS, this 327 cm-1 band is shifted to 312 cm-1, hence we infered that [Ru2]5+ was reduced to [Ru2]4+ by AuNP. In ECSERS, when increasing the applied voltage , the 312 cm-1 band became broad. We deconvoluted the broad band and found that as the voltage was increased, the band position blue-shifted more. Refer to the previous study (J. Phys. Chem. C 2016, 120, 20297−20302 ), we infer that we successfully use ECSERS to trace the valence state of Ru2 moiety and assign 312, 327, 333, and337 cm-1 to [Ru2]4+, [Ru2]5+, [Ru2]5+, and[Ru2]6+ , respectively. The Ru-Ru stretching wavenumber of [Ru2]5+Ni1+ is 327 cm-1 and [Ru2]5+Ni2+ is 333 cm-1. This blue-shift phenomenon may be that nickel is oxidizes from +1 to +2, the interaction of nickel and [Ru2]5+ is weakened, resulting in strong Ru-Ru bonding. In this thesis, we have successfully used the ECSERS technique to observe the vibrational bands of metal complexes in different oxidation states. In the future, if other unstable oxidation state of complex crystals cannot detected by the solid Raman spectrum, we can use ECSRES to solves this problem.

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