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Synthesis, Characterization and Reactivity Control of Ni-Oxygen Adducts with Organic Substrates

Synthesis, Characterization and Reactivity Control of Ni-Oxygen Adducts with Organic Substrates
Kim, Ja lee
DGIST Authors
Kim, Ja lee; Cho, Jae Heung; Jeon, Won Bae
Cho, Jae Heung
Jeon, Won Bae
Issue Date
Available Date
Degree Date
2015. 2
Ni-O2steric effectelectronic effectkinetic
The reactivity of mononuclear metal-O2 adducts, such as metal-superoxo and -peroxo species, has long fascinated researchers in many areas due to the significance of diverse biological and catalytic processes. To understand how the nature of the ligand influences reactivity patterns of the metal-O2 complexes, recently, a systematic study of the relationship between reactivity and ring size of ligand was undertaken for a series of metal-O2 complexes bearing N-tetramethylated macrocyclic chelates in biomimetic chemistry. In this study, the two ligands, CHDAP and Me3-TPADP, were designed and reactivity of Ni-O2 species bearing each ligand was investigated in part I and part II, respectively. For comparison of reactivity according to a steric effect, a set of nickel(III)-peroxo complexes bearing tetraazamacrocyclic ligands, [NiIII(CHDAP)(O2)]+ and [NiIII(TBDAP)(O2)]+, were prepared and fully characterized by various physicochemical methods. The different steric properties of the supporting ligands were confirmed by X-ray crystallography where the CHDPA ligand gives enough space around the Ni-O2 core compared to the TBDAP ligand. In the aldehyde deformylation reaction, the nucleophilic reactivity of the nicke(III)-peroxo complexes was highly dependent on the steric properties of the macrocyclic ligands, with the reactivity order of [NiIII(TBDAP)(O2)]+ < [NiIII(CHDAP)(O2)]+. This result provides fundamental insight into the mechanism of the structure (steric) – reactivity relationship of metal-peroxo intermediates. In part II, the Me3-TPADP ligand was synthesized, and the starting complex, [NiII(Me3-TPADP)(CH3CN)2]2+ (3), and Ni-O2 intermediate, [NiIII(Me3-TPADP)(O2)]+ (4), were prepared and successfully characterized by various methods. Also, the kinetic result of 4 was obtained with external organic substrates. ⓒ 2015 DGIST
Table Of Contents
Part I. A Steric Effect on the Nucleophilic Reactivity of Nickel(III)-O2 Complex 1-- I. Introduction 2-- II. Experimental Section 7-- II-1. Materials and Instrumentation 7-- II-2. Synthesis of Pyridinophan Type Ligands 8-- II-2-a. Pyridine-2,6-dicarbaldehyde (L1) 8-- II-2-b. N,N’-(pyridine-2,6-diylbis(methylene))dicyclohexylamine (L2) 9-- II-2-c. 2,6-bis(chloromethyl)pyridine (L3) 9-- II-2-d. N,N’-di-cyclohexyl-2,11-diaza[3,3](2,6)pyridinophane (CHDAP) 9-- II-3. Generation of Ni Complexes 10-- II-3-a. [Ni(CHDAP)(NO3)]+ (1) 10-- II-3-b. [Ni(CHDAP)(O2)]+ (2) 10-- II-4. X-ray Crystallography 11-- II-5. Reactivity Studies 11-- III. Results and Discussion 13-- III-1. Synthesis and Characterization of CHDAP 13-- III-2. Preparation and Characterization of [NiII(CHDAP)(NO3)]+ (1) 15-- III-3. Characterization and Reactivity Studies of [NiIII(CHDAP)(O2)]+ (2) 19-- III-4. Comparison with Ni Complex bearing TBDAP Ligand 26-- IV. Conclusion 29-- V. References 30-- Part II. Synthesis, Characterization and Reactivity of a Mononuclear Nickel(III)-O2 Complex with Macrocyclic Ligand, Me3-TPADP 36-- I. Introduction 37-- II. Experimental Section 40-- II-1. Materials and Instrumentation 40-- II-2. Synthesis of Ligands 41-- II-2-a. 1,4,7-tris(p-tosylsulfonyl)-1,4,7-triazaheptane (L4) 41-- II-2-b. 3,6,9-tris(p-tosylsulfonyl)-3,6,9,15-tetraazbicyclo[9,3,1]pentadeca-1(15),11,13-triene (L5) 42-- II-2-c. 3,6,9,15-tetraazabocyclo(9,3,1)pentadeca-1(15),11,13-triane (L6) 42-- II-2-d. 3,6,9-trimethyl-3,6,9-triaza-1(2,6)-pyridinacyclodecaphane (Me3-TPADP) 42-- II-3. Generation of Ni Complexes 43-- II-3-a. [Ni(Me3-TPADP)(CH3CN)2] 2+ (3) 43-- II-3-b. [Ni(Me3-TPADP)(O2)]+ (4) 43-- II-4. X-ray Crystallography 44-- II-5. Reactivity Studies 44-- III. Results and Discussion 45-- III-1. Synthesis and Characterization of Me3-TPADP 45-- III-2. Preparation and Characterization of [NiII(Me3-TPADP)(CH3CN)2]2+ (3) 47-- III-3. Characterization and Reactivity Studies of [NiIII(Me3-TPADP)(O2)]+ (4) 51-- IV. Conclusion 56-- V. References 57
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