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  • 學位論文

具不對稱雙氮基脒配基之雙鉬與雙鉻五重鍵 錯合物的合成及其反應性探討

Synthesis and Reactivity of Quintuple Bonded Dimolybdenum and Dichromium Complexes with Unsymmetrical Amidinates

指導教授 : 蔡易州

摘要


本實驗室曾使用2,6-二異丙基苯基取代的雙氮基脒配基,合成出具對稱結構的雙鉬及雙鉻五重鍵錯合物M2[μ-η2-N(Dipp)C(H)N(Dipp)]2 (M = Mo, Cr; Dipp = 2,6-iPr2C6H3),並利用其低價數、低配位的特性,活化許多不同的有機小分子。然而,有別於以往使用對稱的雙氮基脒,本論文欲以不對稱的雙氮基脒作為配基,分別合成雙鉬及雙鉻五重鍵錯合物,並嘗試和各類有機小分子進行反應,期望能有截然不同的結果。 鉬的方面,我們以2,6-二異丙基苯基與2,6-二乙基苯基取代的雙氮基脒為配基,合成出雙鉬四重鍵錯合物[Li(THF)4][Mo2(μ-Cl)Cl2[μ-κ2-N(Dipp)C(H)N(Dep)]2] (1),且成功還原為不對稱雙鉬五重鍵錯合物Mo2[μ-κ2-N(Dipp)C(H)N(Dep)]2 (Dep = 2,6-Et2C6H3) (2),接著嘗試將錯合物2與有機小分子進行反應,目前仍得到與以往類似的結果。 另一方面,我們利用2,6-二異丙基苯基與2,6-二甲基苯基取代的雙氮基脒為配基,合成出雙核鉻二價金屬錯合物Cr2(μ-Cl2)[μ-κ2-N(Dipp)C(H)N(Dmp)]2(THF)2 (Dmp = 2,6-Me2C6H3) (3),且成功地將之還原為不對稱雙鉻五重鍵錯合物Cr2[μ-κ2-N(Dipp)C(H)N(Dmp)]2 (4),將其和對甲基苯疊氮反應,可得到錯合物(μ-p-tolylN)2(p-tolylN)2Cr2[μ-η2-N(Dipp)C(H)N(Dmp)]2 (5);另一方面,若將錯合物4與腈類小分子,苯乙腈及乙腈反應,則分別得到錯合物(μ-κ1C:κ2N-PhCN)2(κ1-PhCN)2Cr2[μ-κ2-N(Dipp)C(H)N(Dmp)]2 (6)與錯合物{Cr2[μ-κ2-N(Dipp)C(H)N(Dmp)]2[N(Dipp)C(H)N(Dmp)]2[κ2-NC(CH3)C(CH3)N]}2 (7),有趣的是在與乙腈反應中,我們能夠完全只得到錯合物7,與先前以對稱雙鉻五重鍵錯合物與之反應後,得到兩種產物的結果相比顯示錯合物4具有較佳的選擇性。 最後,我們將錯合物4與炔類小分子,苯乙炔與三甲基矽乙炔進行反應,分別可得到錯合物(μ-η1:η1-C6H5CCH)Cr2[μ-κ2-(NDipp)CH(NDmp)]2 (8)以及錯合物[μ-η6:η6-(1,3,5-(SiMe3)3C6H3)]Cr2[κ2-N(Dipp)C(H)N(Dmp)]2 (9),其中錯合物9為一具有反三明治結構的雙核鉻錯合物,並有三分子的三甲基矽乙炔環化加成為芳香環,並鑲嵌在雙鉻之間。除此之外,此芳香環化物能夠被苯置換並且脫落分離,我們可以利用這樣的特性,嘗試將錯合物4與其他類似的炔類小分子環化,以期達成相同效果的催化性反應。

並列摘要


We have prepared quintuply bonded dinuclear complexes M2[μ-κ2-N(Dipp)C(H)N(Dipp)]2 (M = Mo, Cr; Dipp = 2,6-iPr2C6H3) with symmetrical amidinato ligands. Due to their low-coordinate and low-valent properties, these quintuply bonded complexes have been employed to activate many small organic molecules. In this thesis, we tried to prepare the quintuply bonded dinuclear complexes supported by unsymmetrical amidinato ligands, and explored their reactivity with various small organic molecules. The unsymmetrical 2,6-diisopropylphenyl- (Dipp) and 2,6-diethylphenyl- (Dep) substituted amidinato ligand was used to synthesize quadruply bonded dimolybdenum complex [Li(THF)4][Mo2(μ-Cl)Cl2[μ-κ2-N(Dipp)C(H)N(Dep)]2] (1), which was subsequently reduced to the quintuply bonded dimolybdenum complex Mo2[μ-κ2-N(Dipp)C(H)N(Dep)]2 (2). However, the reactivity of 2 toward many small organic molecules is similar to those of our reported symmetrically quintuply bonded dimolybdenum amidinates as before. On the other hand, 2,6-diisopropylphenyl- and 2,6-dimethylphenyl- (Dmp) substituted amidinate was used to prepare the dinuclear complex Cr2(μ-Cl2)[μ-κ2-N(Dipp)C(H)N(Dmp)]2(THF)2 (3), which was subsequently reduced to the quintuply boned dichromium complex Cr2[μ-κ2-N(Dipp)C(H)N(Dmp)]2 (4). Treatment of 4 with p-tolyl azide afforded the complex (μ-p-tolylN)2(p-tolylN)2Cr2[μ-κ2-N(Dipp)C(H)N(Dmp)]2 (5). In addition, treatments of 4 with benzonitrile and acetonitrile produced the complex (μ-κ1C:κ2N-PhCN)2(κ1-PhCN)2Cr2[μ-κ2-N(Dipp)C(H)N(Dmp)]2 (6) and {Cr2[μ-κ2-N(Dipp)C(H)N(Dmp)]2[N(Dipp)C(H)N(Dmp)]2[κ2-NC(CH3)C(CH3)N]}2 (7). Notably, 7 was the only isolable product from the reaction of 4 and acetonitrile, in contrast with the reaction of symmetrical quintuple bonded dichromium complex with acetonitrile, from which two products were isolated. Therefore, complex 4 shows much better selectivity toward acetonitrile. Interestingly, treatment of 4 with phenylacetylene and trimethylsilylacetylene led to the isolation of the [2+2] cycloadduct (μ-η1:η1-C6H5CCH)Cr2[μ-κ2-(NDipp)CH(NDmp)]2 (8) and the inverted sandwich complex [μ-η6:η6-(1,3,5-(SiMe3)3C6H3)]Cr2[κ2-N(Dipp)C(H)N(Dmp)]2 (9), respectively. Complex 9 is a dichromium complex with a tristrimethylsilylbenzene-bridged structure, where tristrimethylsilylbenzene was formed by three molecules of trimethylsilylacetylene via [2+2+2] cycloaddition. It is noteworthy that tristrimethylsilylbenzene of 9 is labile and can be replaced by benzene. Accordingly, we take advantage of this property of 4 to react with other alkynes, and anticipate catalytic reactions to occur.

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