環銥化金屬錯合物之合成及其催化反應

Abstract

本論文主要設計合成具有o-(diphenylphosphino)(N-benzylidene)aniline (P~N ligand)為主體的配位體，探討其與銥金屬的配位化學，進而利用這些金屬化合物作為催化劑，測試其在氫胺化與還原胺化等反應。 合成了不同P~N配位基La~Ld，在室溫下可以與[IrCl(COD)]2形成膦配位之銥金屬錯合物[P-(LX)Ir(COD)Cl](X= a. b. c. d) (13a~13d)；並且藉由加入銀鹽或是一氧化碳，造成銥金屬中心產生空配位，促使銥金屬錯合物13a進行環銥化反應，造成分子內碳-氫鍵的活化，形成環銥化金屬錯合物14、15，而從X光結構分析和1H-NMR，都可以發現到Ir-H的形成；並且環銥化金屬錯合物14可以在一氧化碳環境下，加入Et4NCl，就可以轉換形成銥金屬錯合物15。而環銥化金屬錯合物14與過量的三苯基膦反應，並且加入Et4NBr，則會形成環銥化金屬錯合物16。而銥金屬錯合物13b與一氧化碳作用後，形成除了磷、氮配位外，還有氧原子配位之銥金屬錯合物17。而具有立體障礙的銥金屬錯合物13d在與NaBArF4（ArF=3,5-C6H3(CF3)2）反應後，其苯環上的第三丁基成功阻止了碳-氫鍵活化反應，形成銥金屬錯合物[(P~N)Ir(COD)]BArF4 (18)。 在催化應用上，使用環銥化金屬錯合物15與NaBArF4反應所得之錯合物，可以應用在分子內和分子間的胺化反應；並且也可以藉由NaBArF4扮演布忍斯特酸的角色，在水中快速將醛和苯胺形成為亞胺化合物，而其相同的銥化金屬錯合物也可以在one-pot反應條件下，以Et3SiH為還原劑，將carbonyl化合物還原胺化得到對應的胺化合物。

A series of P~N ligands (o-(diphenylphosphino)(N-benzylidene)- aniline) were prepared by the acid catalyzed condensation of 2-(diphenylphosphino)- aniline with the corresponding aldehydes or ketones. Reaction of ligand La~Ld with [Ir(COD)Cl]2 provided the substitution product [(P-(LX)Ir(COD)Cl](X= a. b. c. d) (13a~13d). Treatment of 13a with AgBF4 yielded the cyclometalled iridium hydride complex [P,N,C-(P~N)Ir(COD)H]BF4 (14). Carrying out the substitution of [Ir(COD)Cl]2 with 13a under atmospheric pressure of CO resulted in the formation of [P,N,C-(P~N)IrH(CO)Cl] (15). Conversion of 3 into 4 can also be achieved by the substitution reaction of 14 with CO in presence of tetraethylammonium chloride. Moreover, treatment of 14 with triphenylphosphine and tetraethylammonium bromide under atmospheric pressure of CO resulted in the formation of [P,N,C-(P~N)Ir(CO)(PPh3)H] (16). However, carrying out the substitution of [Ir(COD)Cl]2 with Lb under atmospheric pressure of CO resulted the formation of [P,N,O-(P~N)Ir(CO)HCl] (17). Finally, treatment of 13d with NaB[3,5-C6H3(CF3)2]4 (denoted as NaBArF4) afforded [(P~N)Ir(COD)]BArF4 (18) without the formation of C-H activation product due to the steric effect. All iridium complexes were not good catalysts for hydroamination. However, the combination of 15 with NaBArF4 provided a good catalytic system for both intra- and intermolecular hydroamination of alkynes. Further, in the presence of NaBArF4 acting as Bronsted acid, complex 15 show an excellent activity on reductive amination of aldehydes in water.