Design, Synthesis, and Oxidation Reactivity of Palladacyclic Complexes Containing N-donor Ligands

Author

Ava Behnia, The University of Western OntarioFollow

Degree

Doctor of Philosophy

Program

Chemistry

Supervisor

Richard Puddephatt

2nd Supervisor

Johanna Blacquiere

Joint Supervisor

Abstract

This thesis describes the synthesis and reactivity of complexes containing the cycloneophyl-Pd(II) group, PdCH₂CMe₂C₆H₄, in combination with N-donor ligands. These compounds contain both alkyl- and arylpalladium bonds and the selectivity of bond cleavage in reactions with oxidants and protic reagents is studied, often involving oxidative addition and reductive elimination reaction sequences.

The diimine ligand in [Pd(CH₂CMe₂C₆H₄)(MesN=CH-CH=NMes)] does not support formation of stable palladium(IV) complexes, but reactions with Br₂ or I₂ lead to reductive elimination by C-C bond formation of 1,1-dimethylcyclobutabenzene while the reaction with H₂O₂ gives [Pd(CH₂CMe₂C₆H₄O)(MesN=CH-CH=NMes)] by overall selective oxygen atom insertion into the aryl-palladium bond.

Coordination of the ligand 2-C₅H₄NCH=N-2-C₆H₄OH, 3-L1H, led to protonolysis of the arylpalladium bond to give a neophyl complex [Pd(CH₂CMe₂C₆H₅)(k³-N,N',O-3-L1)], which then isomerized to [Pd(2-C₆H₄-t-Bu)(k³-N,N',O-3-L1)], by a sequence of reactions that includes reversible C-H bond activation. The combination of a Pd(II) precursor with a diimine-phenol ligand and an oxidant (H₂O₂ or O₂) under different conditions has given both a molecular square and a molecular tetrahedron by self-assembly of building blocks comprising Pd(II) centres coordinated to oxidized forms of the ligand.

The complex [Pd(CH₂CMe₂C₆H₄){κ²-N,N’-N(CH₂-2-C₅H₄N)₂(CH₂CH₂CH₂OH)}] reacted with aqueous CO₂ and H₂O₂ to give complex [Pd(CO₃){κ³-N,N’,N’’-N(CH₂-2-C₅H₄N)₂(CH₂CH₂CH₂OH)}], and organic products resulting from a unique form of neophyl rearrangement. The complexes [Pd(CH₂CMe₂C₆H₄)(κ²-N,N′-L)], L = RO(CH₂)₃N(CH₂−2-C₅H₄N)₂, R = H or Me, react with Br₂, I₂, O₂ or H₂O₂ to give Pd(IV) complexes which are sufficiently stable to isolate or to detect spectroscopically, but which decompose slowly in solution by reductive elimination.

Recommended Citation

Behnia, Ava, "Design, Synthesis, and Oxidation Reactivity of Palladacyclic Complexes Containing N-donor Ligands" (2018). Electronic Thesis and Dissertation Repository. 5575.
https://ir.lib.uwo.ca/etd/5575