Date of Award

8-20-2007

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Irina P. Smoliakova

Abstract

Cyclopalladated complexes (CPCs) are a class of organometallic compounds with a variety of applications. Enantiopure CPCs have many important properties; however, until recently, most studies had been conducted using complexes derived from optically active α-methylbenzyl amines and related compounds. The focus of the present study was synthesis and characterization of a new type of enantiopure CPCs derived from 2-oxazolines with different substituents at positions two and four. Direct cyclopalladation of 2-oxazolines using palladium(ii) acetate in acetic acid provided dimeric CPCs in good to excellent yields. Due to the endo-effect, the preference for incorporation of the iminic C=N bond in the palladacycle, endo -CPCs of oxazolines were the major or sole products of cyclopalladation. exo-CPCs were also synthesized, but generally in lower yield using more rigorous conditions. It was also found that aliphatic C(sp 3)-H bonds could be activated to provide an exo-CPC. Dimeric exo- and endo-CPCs were converted to the corresponding monomeric triphenylphosphine complexes. Reaction of 2-aryl-2-oxazoline derived CPCs with m-CPBA resulted in oxygen insertion into the Pd-C bond, with formation of either homoleptic (oxazolinyl-κ 2N,O)2Pd complexes or (oxazolinyl-κ 2N,O)Pd-μ-(m-chlorobenzoato) 2Pd(oxazolinyl-κ2N,O) dimeric complexes. Synthesis and purification of mono-oxazoline pre-ligands, mono-oxazolinyl CPCs and related compounds was followed by structural determination and characterization. This research involved the application of a wide variety of synthesis, purification and analysis techniques. The principle methods used in this research include: infrared spectroscopy, 1H, 13C and 31P one- and two-dimensional nuclear magnetic resonance spectroscopy, and single crystal X-ray crystallography. Purity and elemental composition of the synthesized compounds were determined using elemental analysis.

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