Low-Coordinated Multiply-Bonded Dirhenium Complexes and Low-Valent Diniobium Complexes: Syntheses and Reactivity Study

低配位雙錸多重鍵錯合物及低價數雙鈮錯合物之合成及其化性研究

施建宏(Chien-Hung Shih)

指導教授 ： 蔡易州

國立清華大學/理學院/化學系/碩士(2012年)

https://doi.org/10.6843/NTHU.2012.00234

摘要

本論文分為三部分，其第一部份研究以去質子化雙氮基脒配基Li[HC(N-2,4,6-Me3C6H2)]和[nBu4N]2[Re2Cl8]合成出中間產物Re26+雙錸(III)四重鍵錯合物[nBu4N]{(μ-Cl)Cl4Re2[μ-η2-HC (N-2,4,6-Me3C6H2)2]2} (3)和[nBu4N]2{(μ-Cl)2Cl4Re2[μ-η2-HC (N-2,4,6-Me3C6H2)2]2} (4)，其雙錸(III)四重鍵錯合物鍵長分別為2.2492(4) Å及2.262(3) Å；進一步的以三當量鋅粉還原錯合物3和4，當溶劑選擇四氫呋喃及甲苯混和液，合成出Re2Cl2(H)2[μ-η2-HC(N-2,4,6-Me2C6H2)2]2 (2)，溶劑選擇甲苯合成出另一產物Re2Cl3(H) [μ-η2-HC(N-2,4,6-Me2C6H2)2]2 (5)，2和5皆為雙錸(III)四重鍵錯合物，其雙錸(III)四重鍵錯合物鍵長分別為2.1853(6) Å及2.1890(7) Å，相較於3和4鍵長相對較短。令人振奮的是也成功合成出雙錸(II)五重鍵錯合物Re2Cl2[μ-η2-HC(N-2,4,6-Me2C6H2)2]2 (6)；特別的是同時存在碳−氫鍵氧化加成的雙錸(III)四重鍵錯合物(μ-η2-H){ReCl[μ-η2-HC(N-2,4,6-Me2C6H2)2]ReCl[μ-η2-HC(N-2,4,6-Me2 C6H2)(N-2-Me-4-Me-6-(η1-CH2)C6H2)} (7)，在單晶中6和7間存在著1:1的比例，其雙錸(II)五重鍵錯合物鍵長為2.1852(13) Å，雙錸(III)四重鍵錯合物鍵長為2.1848(6) Å，由結果顯示雙錸鍵長並無太明顯的變化。
第二部份研究將配基換成中性配基為雙二苯基膦甲烷，和[nBu4N]2[Re2Cl8]及三當量鋅加入四氫呋喃於100 °C下加熱50小時，可得一產物ClRe[μ-η2-H2C(PPh2)2]ReCl[μ-η2-H2C(PPh(η1-C6H4)2] (12)，12是經由雙二苯基膦甲烷配基上的苯基進行了兩次碳−氫鍵的氧化加成反應所形成的。令人感到意外的也成功得到四核的錸(II)金屬錯合物{ClRe[μ-η2-H2C(PPh2)2]ReCl[μ-η2-H2C(PPh2)2(PPh(η1-C6H4)]} (μ-Cl)2(μ-O){ClRe[μ-η2-H2C(PPh2)2]ReCl[μ-η2-H2C(PPh2)2(PPh(η1-C6 H4)]} (15)，15可能是經由ClRe(H)[μ-η2-H2C(PPh2)2]ReCl[μ-η2- H2C(PPh2)2(PPh(η1-C6H4))] (10)和水反應所生得的產物。另外，將10和二苯乙炔進行反應，成功合成出C2H(Ph)2ClRe[μ-η2-H2C(PPh2)2]ReCl[μ-η2-H2C(PPh2)2(PPh(η1-C6H4)] (18)，其反應機制為二苯乙炔以1,2插入(insertion)所形成的產物。
第三部份研究將NbCl3(DME)和雙氮基脒配基Li[HC(N-2,6-iPr2C6H3)2]，選擇溶劑甲苯及四氫呋喃分別成功合成出雙鈮錯合物(μ-Cl)3[Li(THF)2(μ-Cl)2][Nb(κ2-HC(N-2,6-iPr2C6H3)]2 (19)及單鈮錯合物NbCl2(THF)[η2-HC(N-2,6-iPr2C6H3)2] (20)，其19雙鈮鍵長2.6457(6) Å。將雙鈮錯合物19和六當量疊氮化鈉於四氫呋喃下反應，成功合成出雙核鈮(VI)金屬錯合物(N3H)Nb{[(μ-Cl)2[μ-η2-HC (N-2,6-iPrC6H3)]2}Nb(N3)2 (21)及(H2O)Nb{[(μ-Cl)2[μ-η2-HC(N-2,6- iPrC6H3)]2}Nb(N3)2 (22)，此兩結構皆為疊氮化鈉進行還原反應，脫去一分子氮氣，鈮金屬中心進行氧化反應。另將19和對甲基苯疊氮及1-金剛烷基疊氮，皆成功得到單鈮(VI)金屬亞胺錯合物(η1-p-tolyN)NbCl2(THF)[η2-HC(N-2,6-iPr2C6H3)2] (25)和(η1-AdN)NbCl2 (THF)[η2-HC(N-2,6-iPr2C6H3)2] (26)，同樣的對甲基苯疊氮及1-金剛烷基疊氮皆脫去一分子氮氣，鈮金屬中心進行氧化反應。

關鍵字

雙錸多重鍵錯合物 ； 雙鈮錯合物 ； 低配位 ； 低價數

並列摘要

Reaction of [nBu4N]2[Re2Cl8] with Li[HC (N-2,4,6-Me3C6H2)] produced two intermediate Re26+ complexes, [nBu4N]{(μ-Cl) Cl4Re2[μ-η2-HC(N-2,4,6-Me3C6H2)2]2} (3) and [nBu4N]2{(μ-Cl)2 Cl4Re2[μ-η2-HC(N-2,4,6-Me3C6H2)2]2} (4), which have two bridging amidinate ligands. Complex 3 has a chloride atom bridging to the rhenium centers, while 4 has two chloride atoms bridging to the rhenium. The dirhenium quadruple bond length of 3 and 4 are 2.2492(4) Å and 2.262(3) Å, respectively. Treatment of 3 and 4 with three equiv of zinc powder in the mixture solvents of THF/Toluene engendered the formation of a quadruply-bonded dirhenium complex Re2Cl2(H)2 [μ-η2-HC(N-2,4,6-Me2C6H2)2]2 (2). In addition, Re2Cl3(H) [μ-η2-HC(N-2,4,6-Me2C6H2)2]2 (5) was also isolated when the solvent is toluene. The dirhenium quadruple bond length of 2 and 5 are 2.1853(6) Å and 2.1890(7) Å, respectively. Subsequent reduction of 3 and 4 with three equiv of zinc powder gave the first example of the quintuply-bonded dirhenium complex Re2Cl2[μ-η2-HC (N-2,4,6-Me2C6H2)2]2(6) (vide supra) and the quadruply-bonded complex (μ-η2-H){ReCl[μ-η2-HC (N-2,4,6-Me2C6H2)2]ReCl[μ-η2-HC(N-2,4,6-Me2C6H2)(N-2-Me-4-Me-6- (η1-CH2)C6H2)} (7) (vide supra), which has C−H bond activation of methyl group. Complexes 6 and 7 are in equilibrium in a ratio of 1:1 crystal. The dirhenium quintuple bond length of 6 is 2.1852(13) Å. The dirhenium quadruple bond length of 7 is 2.1848(6) Å. The results display that the dirhenium bond length are all similar.
Moreover, the dirhenium(II) complex ClRe[μ-η2-H2C(PPh2)2]ReCl [μ-η2-H2C(PPh(η1-C6H4)2] (12) was prepared form the reaction of [nBu4N]2[Re2Cl8] with three equiv of zinc powder and two equiv of bis(diphenylphosphino)methane in THF. The formation of 12 is possibly via double C−H bond activation. Surprisingly, a novel tetrarhenium complex {ClRe[μ-η2-H2C(PPh2)2]ReCl[μ-η2-H2C(PPh2)2(PPh(η1-C6H4)]} (μ-Cl)2(μ-O){ClRe[μ-η2-H2C(PPh2)2]ReCl[μ-η2-H2C(PPh2)2(PPh (η1-C6H4)]} (15) is generated under the same condition. The possible formation of 15 is assumed from the reaction of ClRe(H)[μ-η2- H2C(PPh2)2]ReCl[μ-η2-H2C(PPh2)2(PPh(η1-C6H4))] (10) with water. Besides, the reaction between diphenylacetylene, and complex 10 yielded C2H(Ph)2ClRe[μ-η2-H2C(PPh2)2]ReCl[μ-η2-H2C(PPh2)2(PPh(η1-C6H4)] (18), which was formed via 1,2-insertion of diphenylacetylene.
Treatment of NbCl3(DME) with Li[HC(N-2,6-iPr2C6H3)2] in the different solvents of toluene and THF engendered the formation of a diniobium complex (μ-Cl)3[Li(THF)2(μ-Cl)2][Nb(κ2-HC(N-2,6- iPr2C6H3)]2 (19) and a mononiobium complex NbCl2(THF) [η2-HC(N-2,6-iPr2C6H3)2] (20), respectively. To further investigate the reactivity of the diniobium complex 19 with organic azides. The diniobium cmplexes (N3H)Nb{[(μ-Cl)2[μ-η2-HC(N-2,6-iPrC6H3)]2} Nb(N3)2 (21) and (H2O)Nb{[(μ-Cl)2[μ-η2-HC(N-2,6- iPrC6H3)]2}Nb(N3)2 (22) are afforded from reaction of 19 with six equiv sodium azide. The results are all similar and show that the sodium azide were reduced and released one molecular of nitrogen. Reaction of 19 with p-tolyl-azide or 1-adamantyl azide gave rise to the formation of two mononiobium complexes (η1-p-tolyN)NbCl2(THF)[η2-HC (N-2,6-iPr2C6H3)2] (25) and (η1-AdN)NbCl2(THF)[η2-HC (N-2,6-iPr2C6H3)2] (26), respectively. The results are all similar and display that p-tolyl-azide or 1-adamantyl azide were reduced and released one molecular of nitrogen.

參考文獻

(78) 黃于倫, 國立清華大學化學研究所博士論文, 2008.

(69) 呂端晏, 國立清華大學化學研究所博士論文, 2011.

(26) 顏君旭, 國立清華大學化學研究所碩士論文, 2009.

(81) 顏君旭, 國立清華大學化學研究所博士論文, 2009.

(37) Tsai, Y.-C.; Wang, P.-Y.; Chen, S.-A.; Chen, J.-M. J. Am. Chem. Soc. 2007, 129, 8066.