二價錫氫化合物之合成與反應性測試以及硼烷路易士酸調控其進行脫氫偶合反應之動力學探討

Synthesis and Reactivity of Sn(II) Hydride Complexes and Kinetic Studies of Borane Lewis Acid Mediated Dehydrocoupling Reactions.

賴宇樺(Yu-Hua Lai)

指導教授 ： 劉學儒

國立交通大學/理學院/應用化學系所/碩士(2020年)

摘要

本研究主要分為兩大章節：第一章報導如何分離出熱穩定存在且立障小的二價錫氫錯合物LPhSnH [LPh=2,5-bis(pyrid-2-yl)-3,4-bisphenyl-pyrrolato]。之前實驗室張偉榤學長發現LPhSnCl 與 M[BHsBu3]（M = Li or K）的反應皆可產生LPhSnH，不過LPhSnH不穩定會進行脫氫偶合(dehydrocoupling)反應產生一價錫類炔錯合物 (distannyne, (LPhSn)2)，因此無法有效地單離出LPhSnH。在此反應中，除了鹽類MCl的生成之外，同時也會產生一份BsBu3。於是改變合成策略，使用pinacolborane (HBpin)作為氫化試劑並和新合成出的前驅物LPhSnOMe反應可成功合成出LPhSnH。這樣合成途徑所得到的LPhSnH在溶液中穩定性大幅提升。而此反應所得到的副產物BpinOMe屬於路易士酸性較弱的硼酯類化合物，因此我們懷疑路易士酸性較強的硼烷化合物BsBu3會加速LPhSnH脫氫偶合的反應。後續透過一系列動力學的實驗探討BsBu3與LPhSnH之間的關係，並推導出反應機構。除此之外，分別改變配基和路易士酸的立障，進一步探討立障是否會對脫氫偶合反應造成影響。
　　第二章的部分針對LPhSnH做後續的反應性和催化反應研究。
探討LPhSnH是否會與含有不飽和鍵結的小分子反應；除此之外，LPhSnH作為催化劑在硼氫加成反應上有很好的催化效果，若換成配基立障較大的MeLSnH [MeL = 2,5-di(6-methylpyrid-2-yl)pyrrole)]，會使轉化效率下降。我們認為合成出產率高、立障小且熱穩定存在的二價錫氫錯合物是相當重要的發現，對於未來發展其他二價14族氫化物來說是可參考的方向。

關鍵字

二價錫氫化合物 ； 脫氫偶合反應 ； 路易士酸

並列摘要

In the first chapter of this study, we reported the synthesis of thermally stable tin(II) hydrides LPhSnH and MeLSnH supported by sterically unencumbered NNN pincer-type ligands (LPh = 2,5-bis(pyrid-2-yl)-3,4-bisphenyl-pyrrolato ; MeL = 2,5-di(6-methylpyrid-2-yl)pyrrole ). Previously, we found that treaments of LPhSnCl with M[BHsBu3] (M = Li or K) in THF afforded LPhSnH via metathesis reactions, which then spontaneously decomposed into (LPhSn)2 in solution in company with dihydrogen formation at room temperature. Besides MCl precipitates generated from these reactions were observed visually, the Lewis acid BsBu3 was also detected as the byproduct by 1H NMR spectroscopy. Due to its thermally unstable nature, we couldn’t isolate LPhSnH as a pure compound. Alternatively, treatment of tin methoxy complex (LPhSnOMe) with pinacolborane (HBpin) cleanly produced LPhSnH in high yield without observable decomposition to (LPhSn)2. Thus, the boron-contaning byproducts BsBu3 (from the reactions using M[BHsBu3]) and MeOBpin (from the reaction using HBpin) seem to affect the rate of decomposition of LPhSnH. A series of kinetic experiments was taken and we found that the Lewis acidic BsBu3 catalyzes the dehydrocoupling reaction of LPhSnH leading to the formation of (LPhSn)2.
　　In the second part, we disclosed the reactivity of LPhSnH towards unsaturated compounds including carbonyls, alkenes and alkynes. We further demonstrated that LPhSnH is an effective catalyst for carbonyl hydroboration.

並列關鍵字

Tin(II) hydride complexes ； Dehydrocoupling reactions ； Lewis acid

參考文獻

1. K.A. Erickson; D.S. Wright; R. Waterman. J. Organomet. Chem. 2014, 751, 541-545.

2. P. Bellham; M.S. Hill; G. Kociok-Kohn; D.J. Liptrot. Chem. Commun. 2013, 49, 1960-1962.

3. R.L. Melen. Chem. Soc. Rev. 2016, 45, 775-788.

4. M.S. Hill. Springer 2010, 189-216.

5. T. Imori; V. Lu; H. Cai; T.D. Tilley. J. Am. Chem. Soc. 1995, 117, 9931-9940.