Diyne and bisalkynyl complexes of pentamethylcyclopentadienyliridium

• Main Author: Li, Yongjia
• Other Authors: Leong Weng Kee
• Format: Theses and Dissertations
• Language: English
• Published: 2015
• Subjects: DRNTU::Science::Chemistry
• Online Access: https://hdl.handle.net/10356/65638
• Institution: Nanyang Technological University

The reductive elimination of [Cp*Ir(CO)(C≡CPh)2] to [Cp*Ir(CO)(PhC≡C-C≡CPh)] has been investigated. This reaction proceeds at an accelerated rates in protic solvents, and the reaction pathway has been examined computationally and experimentally. The effects of substitution at the phenyl ring and of the ancillary ligand have also been examined. The reactivity of both bis(alkynyl) complexes [Cp*Ir(CO)(C≡CAr)2] and diyne complexes [Cp*Ir(CO)(ArC≡C-C≡CAr)] have also been investigated. The diyne complex reacted with two electron-donors L to form the 4-membered metallacycles [Cp*Ir(L){C(C≡CAr)=C(Ar)C=O}] by an intramolecular cycloaddition reaction. The kinetics of the reaction has been measured and the reaction pathway studied computationally. The photochemical reaction of the diyne complex with 3-hexyne afforded an allyl complex, its reaction with phenylacetylene afforded the unstable iridapentadiene species [Cp*Ir(CO){CH=C(Ph)C(Ph)=C(CCPh)}], and acid-catalysed hydrolysis yielded the iridacyclopentenone [Cp*Ir(CO){C(Ph)=CHC(=O)CHPh}]. The bisalkynyl complexes [Cp*Ir(L)(C≡CAr)2] were found to undergo acid-catalysed aerobic oxidation to form the iridaindenes [Cp*Ir(L){C6H4-1,2-CH=CC(=O)C(=O)Ar}]. They also undergo an Arbuzov-type reaction with P(OMe)3 in the presence of CH3COOH to give the iridacyclic phosphates [Cp*Ir(L){C(Ar)=C[P(=O)(OMe)2]C=CHAr}]. Reaction pathways for both reactions have been proposed.