含氮雜環碳烯金屬錯合物之合成、性質及應用

Abstract

本篇論文中，我們探討飽和及未飽和含氮雜環碳烯銥金屬錯合物在催化活性、碳烯－金屬化學鍵的穩定性以及配位化學上的差異。藉由在咪唑的氮上修飾苯甲基為取代基的銥金屬碳烯錯合物來加以闡述。 藉由金屬碳烯轉移反應，我們成功地將未飽和含氮雜環碳烯從銀金屬轉移至銥金屬前驅物[Ir(COD)Cl]2，接著通入一氧化碳來取代弱配位性的環辛二烯而得到順式的cis-[(IBn)Ir(CO)2Cl]。另外，也藉由(SIBn)W(CO)5與 [Ir(COD)Cl]2作用，成功將碳烯轉移至銥金屬上，而直接合成出[(SIBn)Ir(CO)2Cl]。當膦化物與上述的 [(NHC)I(CO)2Cl]反應時，膦化物會取代反式位置上的CO取代基而形成[(NHC)Ir(CO)(PR3)Cl]。由X光單晶繞射分析鑑定，顯示[(IBn)Ir(CO)(PR3)Cl]與[(SIBn)Ir(CO)(PR3)Cl]上的碳烯與銥金屬鍵長相當。並且從光譜分析及晶體結構數據發現[(NHC)Ir(CO)(PR3)Cl]的錯合物與Vaska’s 錯合物相當類似。因此，我們推論其含氮雜環碳烯與膦化物在ㄧ價銥金屬上有相似的配位能力。此外，將所合成出來的銥金屬錯合物應用在N-alkylation催化反應上，其係經由氫轉移反應來成功得到二級胺化物。從催化反應的結果來看，未飽和與飽和碳烯銥金屬錯合物在催化活性上並沒有引人注目的差異，但是(SIBn)Ir(CO)(PR3)Cl還是比其他銥金屬錯合物有稍好的活性。 另一方面，成功合成出2,7-bis(1-mesitylimidazolium-3-yl)naphthyridine鹽類，相同地經由金屬碳烯轉移反應，將這多螯合型配位基的銀錯合物與Pd(PhCN)Cl2反應，在CH3CN為溶劑下，可以得到雙分子鍵結型態的含氮雜環碳烯二價鈀金屬錯合物，並且探討此錯合物結構。

In this thesis, we have synthesized both saturated and unsaturated N-heterocyclic carbene iridium complexes [(NHC)Ir(CO)2Cl] (where NHC = IBn, SIBn) and have studied the difference between these complexes on coordination behavior, stability and catalytic activity. The unsaturated carbene complex cis-[(IBn)Ir(CO)2Cl] was prepared via the carbene transfer from the corresponding silver carbene complex to [Ir(COD)2Cl]2 followed by the ligand substitution with CO, whereas the saturated one cis-[(SIBn)Ir(CO)2Cl] was obtained directly via the carbene transfer from (SIBn)W(CO)5. Treatment of phosphines with [(NHC)Ir(CO)2Cl] resulted the formation of the products with the phosphine ligand trans to the carbene moiety via substitution of CO. X-ray structural determinations show that the distances of Ir-C(carbene) in both [(IBn)Ir(CO)(PR3)Cl] and [(SIBn)Ir(CO)(PR3)Cl] are essentially the same. Analyses of spectroscopic and crystal structural data of iridium complexes (NHC)Ir(CO)(PR3)Cl and the Vaska’s complex reveal that NHC ligands and phosphines have a similar donating ability toward Ir(I) metal center. All iridium complexes studied in this work are good pre-catalysts on N-alkylation of amines with alcohols via hydrogen transfer reduction. It appears no dramatic difference on the catalytic activity among these iridium carbene complexes; but the saturated carbene complex SIBn-Ir(CO)(PR3)Cl appears to be slightly more active. On the second project, 2,7-bis(1-mesitylimidazolium-3-yl)naphthyridine salt was used as a carbene precursor, which reacted with Ag2O to yield the corresponding silver carbene complex. Treatment of this silver complex with Pd(PhCN)2Cl2 in CH3CN yielded the dimeric NHC-Pd(II) complex. Structural determination of the palladium complex was discussed.