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標題: | 新穎亞銅金屬簇與銠鎳和銠鈷混金屬串之合成與鑑定 Novel Cuprous Clusters with Short Unbridged Cu(I)-Cu(I) Separations and Rh-based Heteronuclear Metal String Complexes Mixed with Ni or Co atoms |
作者: | Po-Hsien Ho 何柏賢 |
指導教授: | 彭旭明(Shie-Ming Peng) |
關鍵字: | 親銅性,異核金屬串錯合物, Cuprophilicity,Hetronuclear metal string complexes, |
出版年 : | 2013 |
學位: | 博士 |
摘要: | 在本論文中,研究方向分為兩部分:在第一部分合成出三個多核亞銅金屬簇,化合物1-3,其中化合物1與2為具有相似結構,皆為環型金屬排列;另一方面,化合物1和2具有少見並且相當短且不需藉由架橋配基連結的Cu(I)-Cu(I)距離,這距離接近或略大於Cu-Cu的凡德瓦耳半徑總合(2.8 Å),透過結構證據顯示亞銅原子間似乎存在特殊作用力,而化合物3為V型金屬簇。在電子光譜上顯示,化合物2和3相較於化合物1具有明顯的紅位移;根據理論計算結果,化合物1為一MLCT電子躍遷;化合物2與之相較後發現,金屬核數上升造成HOMO上升,配基上的芳香性上升則會造成LUMO下降,兩者共同貢獻結果造成化合物2產生紅位移。
在第二部分研究中,利用不同反應條件能夠得到一系列異核金屬串錯合物[NiRhNi(dpa)4(NCS)2] (4), [Rh2Ni(dpa)4(NCS)2] (5), [Rh3Ni2(tpda)4(NCS)2] (6) and [Rh2Ni3(tpda)4(NCS)2] (7)。透過單晶結構解析,紅外線光譜以及核磁共振光譜可以確定異金屬在金屬串中之排列順序;此外,化合物5和7皆具有S = 1的順磁行為,而化合物4和6則是具有反鐵磁行為。另一方面,[Rh2Co3(tpda)4(NCS)2] (8)與[Co5(tpda)4(NCS)2]具有相同電子組態,經由電化學分析,磁性比較和理論計算分析,結果發現在化合物8中具有少見的Rh-Co金屬鍵。 In the first study, we prepared a series of multinuclear cuprous clusters, 1-3, with double-decker conformations. Compounds 1 and 2 both exhibited similarly metallic cyclic arrangements with short and unbridged Cu(I)-Cu(I) bonding interactions. The unbridged Cu(I) pairs in compound 2 are more than that in 1 and reflected in shorter unbridged Cu(I)-Cu(I) distances. In compound 2, the shortest bridged Cu(I)-Cu(I) separation is ca. 2.42 Å close to the almost shortest Cu(I)-Cu(I) distance, 2.35 Å in the previous report.35d In addition, compound 1 exhibited the luminescence on 520 nm, but compound 2 is not. The UV-Vis absorption spectra of 2 and 3 are obviously more red-shift than that of 1. Both the luminescence of 1 and the shifts in UV-Vis absorption spectra of 1-3 intrigued us, and then the theoretical calculations were used for compounds 1 and 2. We found that the HOMOs and LUMOs of 1 and 2 are contributed by the d orbitals of all Cu(I) ions and π* orbitals the central aromatic rings, respectively. The excited states of 1 and 2 can be assigned “metal-to-ligand charge transfer (MLCT)”. Due to the increase of nuclearity and aromatic rings in 2, the energy gap between HOMOs and LUMOs is decreased, and red-shift is happened in the UV-Vis absorption spectrum. At the second study, we try to prepare heteronuclear metal string complexes (HSMCs) including Rh and Ni atoms, whereas a series of HSMCs, [NiRhNi(dpa)4(NCS)2] (4), [Rh2Ni(dpa)4(NCS)2] (5), [Rh3Ni2(tpda)4(NCS)2] (6) and [Rh2Ni3(tpda)4(NCS)2] (7) with various Rh and Ni atom numbers were synthesized. Compound 4 is D4 point group and the others are C4 point group. Due to Rh(II)-Rh(II) single bond weaker than other metal-metal multiple bonds, it is easily broken in Rh(II)-Rh(II) single bond at high temperature reactions and resulted in odd Rh(II) atom(s) existing in metal string complexes. Because of the easy break in Rh(II)-Rh(II) single bond, side products are much more at high temperature reactions. The utilization of column-chromatography is more convenient to separate and purify the desired products. Compounds 5, 6 and 7 are asymmetric metal string complexes and reflected in two N≡C strengths (2067 and 2043 cm-1) of the axial ligands. Compound 5 is antiferromagnetic, and compound 6 and 7 are paramagnetic. [Rh2Co3(tpda)4(NCS)2] (8) was obtained with Co, Rh atoms and tpda2- ligand. Ni atoms are just replaced by Co atoms in compound 8, and it is isostructural to compound 7. The χMT values are 1.54 at 350 K and 0.81 at 4K, respectively. Over the whole temperature range from 2–300 K, compound 8 showed χMT values significantly higher than a theoretical spin-only value for a doublet ground state (0.38 emu K mol-1) but lower than that for a quartet ground state (1.88 emu K mol-1). The experimental result of compound 8 is coincident with that from the isoelectronic compound, [Co5(dpzpda)4(NCS)2]45. It indicates that the delocalized Rh-Rh, Co-Co and even Rh-Co bonds exist in the Rh2Co3 backbone. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/17378 |
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