雙核鉬金屬多重鍵之合成與結構研究

Synthesis and Characterizations of Multiply-Bonded Dimolybdenum Complexes

劉信呈(Shin-Cheng Liu)

指導教授 ： 蔡易州

國立清華大學/理學院/化學系/碩士(2010年)

摘要

本篇論文主要在研究以雙氮基脒及重氮氨基做為配基合成出雙鉬多重鍵錯合物。以去質子化後的雙氮基脒Li[HC(N-2,6-Et2C6H3)2]為配基與MoCl3(THF)3反應合成出正二價的三核鉬金屬錯合物Mo2(μ-Cl)[Cl2MoLi(μ-Cl2)(thf)(OEt2)][μ-η2-HC(N-2,6-Et2C6H3)2]2 (1)。將1以兩當量的KC8¬還原以後，可得到具有類似風車型結構的雙鉬四重鍵錯合物Mo2(μ-Cl)[Cl2(μ-Li(thf)2)][μ-η2-HC(N-2,6-Et2-C6H3)2]2 (2)，其鉬-鉬鍵長為2.0817(10)Å；此結構與我們實驗室所報導的兩個四重鍵化合物Mo2(μ-Cl)[Cl2(μ-Li(thf)2)][μ-η2-RC(N-2,6-i-Pr2C6H3)2]2(R = H, Ph)的結構類似。再將2經過兩當量的KC8還原可得到以三片配基及鋰離子分別橋接於雙鉬之間的風車式五重鍵錯合物Mo2(μ-Li)[μ-
η2-HC(N-2,6-Et2C6H3)2]3 (3)，鉬-鉬之間的鍵長為2.0612(4)Å。另一方面，以三比二的比例將去質子化的配基Li[HC(N-2,6-Et2C6H3)2]與MoCl3(THF)3反應合成出錯合物Mo2(μ-Cl)[μ-η2-HC(N-2,6-Et2-
C6H3)2]3(4)。以[N(N-2,6-i-Pr2C6H3)2]作為配基合成出結構與錯合物 2相似之正二價的金屬四重鍵錯合物Mo2(μ-Cl)[Cl2(μ-Li(thf)2)][μ-η2-
N(N-2,6-i-Pr2C6H3)2]2 (5)，其鉬-鉬鍵長為2.0877(5)Å。將5以蒽鎂還原之後，可得到蒽配位在雙鉬之間，形成燈籠型的四重鍵錯合物Mo2[μ-η2:η2-anthracene][μ-η2-N(N-2,6-i-Pr2C6H3)2 ]2 (6)；當改以鎂粉作為還原劑時，可得到配基上的一個碳氫鍵被活化的雙鉬四重鍵錯合物(MoH)[Cl2(μ-Mg(thf)2)]Mo[μ-η2-N(N-2,6-i-Pr2C6H3)][μ-η2-N(N-2,6-i-
Pr2C6H3)N(N-2-i-Pr-6-CH3CHCH2-C6H3)](7)，其結構為四配位扭曲的風車型。

關鍵字

雙鉬多重鍵

並列摘要

Treatment of a mixture of MoCl3(THF)3 and zinc powder with the lithiated amidinate Li[μ-η2-HC(N-2,6-Et2C6H3)2] gave the trinuclear molybdenum complex Mo2(μ-Cl)[Cl2MoLi(μ-Cl2)(thf)(OEt2)][μ-η2-
HC(N-2,6-Et2C6H3)2]2 (1), where the central core is a quadruply-
bonded Mo2 unit. Subsequent reduction of complex 1 with 2 equiv KC8 eliminated the pendant molybdenum atom and led to the isolation of a quardruply-bonded complex Mo2(μ-Cl)[Cl2(μ-Li(thf)2)][μ-η2-HC(N-2,6-
Et2C6H3)2]2 (2), displaying a paddlewheel structure, where the Mo-Mo quadruple bond length is 2.0817(10)Å. The structure of 2 is similar to the reported complexes by us Mo2(μ-Cl)[Cl2(μ-Li(thf)2)][μ-η2-RC(N-2,6-i-
Pr2C6H3)2]2(R = H, Ph). Upon reduction of complex 2 with KC8, a novel quintuply-bonded complex Mo2(μ-Li)[μ-η2-HC(N-2,6-Et2C6H3)2]3 (3) was obtained. It is interesting to note that 3 displays a paddlewheel structure with a lithium ion coordinated to two quintuply-bonded Mo centers. The Mo-Mo bond length was determined to be 2.0612(4)Å by single crystal X-ray diffraction. In addition, the reaction of a mixture of MoCl3(THF)3 and KC8 with different concentration of the lithiated amidinate engendered the formation of the quardruply-bonded complex Mo2(μ-
Cl)[μ-η2-HC(N-2,6-Et2C6H3)2]3(4). However, reaction of a mixture of MoCl3(THF)3 and KC8¬ with the lithiated triazenide resulted in the formation of the quardruply-bonded dimolybdenum complex Mo2(μ-
Cl)[Cl2Li(thf)2][μ-η2-N(N-2,6-i-Pr2C6H3)2]2 (5), which is reminiscent of that complex 2 in structure. Further reduction of 5 with magnesium anthracene afforded a lantern type quardruply-bonded complex Mo2[μ-
η2：η2-anthracene][μ-η2-N(N-2,6-i-Pr2C6H3)2]2(6), where the anthracene bridges two Mo centers in an η4 fashion. However, reduction of 5 with magnesium powder resulted in a the isolation of a distorted paddlewheel quardruply-bonded dimolybdenum complex (MoH)[Cl2(μ-Mg(thf)2)]
-Mo[μ-η2-N(N-2,6-i-Pr2C6H3)][μ-η2-N(N-2,6-i-Pr2C6H3)N(N-2-i-Pr-6-CH3CHCH2-C6H3)](7), from which a C-H bond cleavage of one of the isopropyl groups is observed.

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