Synthesis Of Non-heme Iron Oxygenase Model Complexes And Their Catalytic Properties

The research on non-heme iron oxygenases has emerged as a hot project in bioinorganic field, which has attracted much attention. Under mild conditions, the bio-inspired catalysts based on non-heme iron oxygenases can selectively and efficiently catalyze oxidation reactions of a large range of substrate such as alkanes, alkenes and phenols by using "green" oxidants. It may give a promising way to substitute present oxidation processes. In recent years, the development of biological techniques and biomimetic model systems has led to exciting breakthrough in the field of non-heme iron oxygenases. Encouraged by these achievments, in this thesis, the work focused on mimicking the function of non-heme iron oxygenases, especially those for alkane hydroxylation (iron bleomycin (FeBLM)) and catechol's intradiol cleavage dioxygenase (protocatechuic 3,4-dioxygenase (3,4-PCD)). A series of iron complexes were synthesized as functional models of non-heme iron oxygenases, their catalytic properties for the hydroxylation of alkanes and activities for the catechol intradiol-cleavage were investigated.A versatile ligand L¹ (N-(2-(pyridylmethoxyethyl)-N,N-bis(2-pyridylmethyl)amine) and its iron complexes were synthesized. The crystal structures of the iron complexes show that that L¹ can act as a tridentate or pentadentate ligand in monoiron complexes and μ-oxo dinuclear iron complex which was obtained from the reaction of L¹ with Fe(ClO₄)₃. Under mild conditions, the catalytic property of complex [FeL¹Cl]PF₆ (Fe2) was explored by using H₂O₂ as oxidant, which exhibited higher chemo-selectivity than previously reported N₅ ligand iron complexes (A/K = 2.4). The result manifests that the weak coordination of ether oxygen atom from L¹ benefits the metal-based oxidation pathway. Complex FeL¹Cl₃ (Fe3) with a fac-configuration showed a high selectivity in alkane hydroxidation as well as Fe2. The activity and selectivity of Fe3 are higher than the N₃-coordinate analogue with a mer-configuration (A/K = 2.3). While in mCPBA system, the complexes bearing N4O and N₂O₂ ligands exhibited high activities and high regioselectivities (3°/2° = 18.5-34.4). An Fe^III-OOH species was detected when the cyclohexane oxidation catalyzed by [FeL²](ClO₄)₂ (Fe6, L² =N,N-bis(2-pyridylmethoxyethyl)-N-(2-pyridylmethyl)amine) containg an N₂O₂ ligand was monitored by UV-Vis spectrometry.The μ-alkoxo diiron(III,III) complex [FeL⁸(NO₃)]₂(NO₃)² (Fe11, HL⁸ = N,N-bis(2-pyridylmethyl)-N-hydroxylethylamine) containing tripodal N₃O ligand was...