The Reactivity Of Tricyano Osmium(Ⅵ) Nitrido Complexes Containing A O^N Ligand In The Excited State

M≡N have been identified as key intermediates in the chemical or nitrogen-fixing enzyme-catalyzed conversion of N₂ to NH₃,and are also widely used as catalysts for exchange reactions of compounds containing,for example,C≡C or C≡N triple bonds.Some of the more reactive M≡N are also potential nitriding reagents,capable of transferring N atoms directly into various organic substrate molecules and altering the properties of these substrates.Although M≡N have been reported in the literature,few have comparable oxidation capabilities to those of metal oxides（M=O）in biological systems.Highly reactive M≡N has been one of the hot topics of research.In this thesis,the high activity of a tricyanogenic Os^Ⅵ≡N containing a bidentate O^N ligand（2-（2-hydroxy-5-nitrophenyl）benzoxazole）in the excited state was used to oxidise dihydroxybenzenes and aromatic amines and to investigate the reaction mechanism.To advance the study of the reactivity of tricyanogenic osmium nitrides（OsN）containing O^N ligands in the excited state.Chapter 1 focuses on the luminescent properties of some high-valent Os complexes（Os=O and Os≡N）,and summarizes the progress.Moreover,the progress on the oxidation of dihydroxybenzenes and the aromatic amines and the significance of the study have also been summarized.In chapter 2,the photoreaction of OsN with o-dihydroxybenzene and p-dihydroxybenzene have been investigated upon irradiation by a blue LED（λ>460 nm）.The reaction of OsN^*and o-dihydroxybenzene afforded the Os（Ⅱ）o-benzoquinone monoimine compound,（PPh₄）[Os^Ⅱ（L）（CN）₂（CO）（o-NH=Ph=O）][（PPh₄）1],the Os（Ⅳ）monoiminato compound（PPh₄）[Os^Ⅳ（L）（CN）₃（N=Ph（OH）=O）][（PPh₄）2],and Os（Ⅱ）p-benzoquinone monoimine compound（ⁿBu₄N）₂[Os^Ⅱ（L）（CN）₃（p-NH=Ph（OH）=O）][（ⁿBu₄N）₂3]with yields of 15%,40%and 22%,respectively.Moreover,（PPh₄）[Os^Ⅲ（L）（CN）₃（NH₃）][（PPh₄）4],a reduced product of OsN,was isolated with～20%yield.Similarly,OsN^*reacted with p-dihydroxybenzene afforded a series of products,involving the neutral Os（Ⅱ）monoimine complex[Os^Ⅱ（L）（CN）₂（CO）（p-NH=Ph OH）]（5）,the Os（Ⅳ）p-benzoquinone monoiminato complex（PPh₄）[Os^Ⅳ（L）（CN）₃（p-N=Ph=O）][（PPh₄）6]and the Os（Ⅱ）monoimine compound（ⁿBu₄N）[Os^Ⅱ（L）（CN）₃（p-NH=Ph OH）][（ⁿBu₄N）7],respectively with yields of 1%,10%and 50%.[（PPh₄）4]was isolated with a yield of 28%.The product（PPh₄）₂[Os^Ⅱ（L）（CN）₃（o-NH=Ph（OH）=O）][（PPh₄）₂8]was isolated with a yield less than 6%due to the steric effect of H₂Q.In order to clarify the mechanism of the reaction,the origin of the O and N atoms were determined by isotopic labelling experiment.The steady-state emission spectroscopy and nanosecond time-resolved absorption（ns-TA）spectroscopic measurements were used for capturing the intermediates formed between OsN^*and H₂Cat or H₂Q and investigating the quenching effects.The plot of the initial rate method versus Hammett effect of substituents and the KIE effect were investigated.The rate-limiting step of the reaction was proton transfer（PT）and that the initial step was ET-PT.In Chapter 3,we have investigated that the photoreaction of OsN and various aromatic amines upon the irradiation by blue LEDs（λ>460 nm）.The reaction of OsN^*and 2,6-dimethylaniline afforded a mixture of the osmium（Ⅱ）diazonium compound（PPh₄）[Os^Ⅱ（L）（CN）₃（N=N-Me₂Ph）][（PPh₄）9]（10%）and the Os（Ⅱ）benzoquinone diimine compound（PPh₄）[Os^Ⅱ（L）（CN）₃（p-NH=Me₂Ph=NH₂）][（PPh₄）10]（60%）;In this reaction,OsN^*attacked the N atom and the 4-position of the aromatic ring respectively.In order to control the the photoreaction,4-Br-2,6-dimethylaniline was used instead of 2,6-dimethylaniline.And the photoreaction afforded exclusively the osmium（Ⅱ）diazonium compound（PPh₄）[Os^Ⅱ（L）（CN）₃（N=N-Me₂Br Ph）][（PPh₄）11]in about 30%yield.The photoreactions of OsN with diphenylamine,carbazole and indole afforded the compounds（PPh₄）[Os^Ⅱ（L）（CN）₃（p-NH=Ph=NHPh）][（PPh₄）12],（PPh₄）[Os^Ⅱ（L）（CN）₃（NH=Carb）][（PPh₄）13],（PPh₄）[Os^Ⅱ（L）（CN）₃（NH=Indo）][（PPh₄）14]with 35%,45%and 55%yields,respectively.Oxidation of[（PPh₄）10]with H₂O₂（30%in H₂O）afforded（PPh₄）[Os^Ⅳ（L）（CN）₃（N=PhMe₂（O）=O）][（PPh₄）15]in 80%yield,which contained a novel（epoxy）benzoquinone iminato ligand.The products have been well characterized by IR,UV/Vis,¹H NMR,ESI/MS,CHN.The crystal structures of some compounds were further determined by X-ray crystallography.Investigation on the reaction mechanism confirmed that the initial step of the photochemical reaction between OsN^*and aromatic amines is 1e^-transfer（ET）followed by proton transfer（PT）to afford the Os^VNH and amine radical.Chapter 4 provides a summary and outlook about the reactivity of OsN^*.