More importantly, to the best of our knowledge, under visible-light excitation NO 2 -OsN becomes the most oxidizing/electrophilic nitrido species reported. In contrast, NO 2 -OsN is highly luminescent in both solid state and fluid solutions. OsN is very weakly emissive in both the solid state and fluid solution. The photophysical and photochemical properties of the two complexes have been investigated. In this work, we have synthesized a nitro derivative of OsN − ( NO 2 - OsN, NO 2 -HL = 2-(2-hydroxy-4-nitrophenyl)benzoxazole via a similar procedure. Recently, we reported the synthesis of an osmium(VI) nitrido complex − ( OsN, HL=2-(2-hydroxyphenyl)benzoxazole) via the oxidation of an osmium(III) guanidine precursor − ( OsG) 22, 23, 24. Although some of these complexes are strong one-electron oxidants in their excited states, nitrogen atom transfer reactions of these complexes, especially towards inert organic substrates, have not been demonstrated. A number of d 2 nitrido complexes, such as those of Re V and Os VI, have long-lived emissive excited states 15, 16, 17, 18, 19, 20, 21 the emissions of these complexes were shown to originate mainly from metal-centered ligand field 3 excited states. A number of azido complexes, including Ru 2(D(3,5-Cl 2)PhF) 4N 3 (D(3,5-Cl 2)PhF= N, N’-bis(3,5-dichlorophenyl) formamidinate) 9, 10, ( iPrBPDI)CoN 3 ( iPrBPDI=2,6-(2,6- iPr 2-C 6H 3=CPh) 2C 5H 3N) 11, 3 (PDI=2,6-pyridyldiimine) 12, Ni(Et 3P) 2(N 3) 2 13 and (C 5Me 5) 2U(N 3) 14 can also undergo inter- or intramolecular C–H bond activation of alkanes and arenes via in situ generation of putative nitrido intermediates by thermolysis or photolysis.Īpart from the above systems, the use of solar energy to generate highly reactive nitrido complex in the excited state for the nitrogenation of organic substrates is an appealing approach. Previous studies have demonstrated that the ruthenium(VI) nitrido complexes bearing salen-type ligands are highly electrophilic 7 in particular, the complex + (salchda= N, N′-bis(salicylidene)- o-cyclohexyldiamine dianion) is the only well-defined nitrido complex that is able to activate the C–H bonds of alkanes in the presence of pyridine 8. However, these complexes do not undergo C–H bond activation, especially for substrates with unactivated C–H bonds, such as alkanes. Pioneering work by Meyer and Huynh 6 has shown that + (terpy=2,2′:6′,2″-terpyridine) and related complexes are highly electrophilic/oxidizing they react with a variety of organic substrates resulting in the formation of novel osmium complexes in lower oxidation states. Although a variety of transition metal nitrido complexes are known, few have oxidizing ability that are comparable to metal-oxo species, such as Fe IV(O)P + Transition metal nitrido (M≡N) complexes are key intermediates in N 2 fixation they are also potentially useful reagents for the nitrogenation of various organic substrates 1, 2, 3.
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