The search for a highly active nitrido complex that can transfer its nitrogen atom to inert organic molecules remains a challenge to chemists. In this regard, the use of solar energy to generate a reactive nitrido species is an appealing strategy to solve this problem. Here we report the design of a strongly luminescent osmium(VI) nitrido compound, [OsVI(N)(NO2-L)(CN)3]− (NO2-OsN) with emission quantum yield (Φ) and life time (τ) of 3.0% and 0.48 μs, respectively in dichloromethane solution. Upon irradiation with visible light, this complex readily activates the aliphatic C-H bonds of various hydrocarbons, including alkanes. The excited state of NO2-OsN can undergo ring-nitrogenation of arenes, including benzene. Photophysical and computational studies suggest that the excited state of NO2-OsN arises from O^N ligand to Os ≡ N charge transfer transitions, and as a result it possesses [Os = N•] nitridyl character and is highly electrophilic.
A new series of luminescent phosphine copper(i) complexes with cyano- and hydroxyl-substituted 2,2′-bipyridine ligands have been synthesized and structurally characterized. Their luminescent properties have also been investigated in detail.
Six lanthanide compounds have been prepared from a neutral tetra-dentate ligand. Their luminescent and magnetic properties were investigated in detail.
A pair of structurally-similar and stable 8-coordinate high-spin Fe(ii) and Fe(iii) compounds have been obtained. Both compounds exhibit field-induced slow magnetic relaxation behaviour.
A series of polynuclear Cu(i)/Ag(i) complexes have been obtained on the basis of three polytopic ligands. Their structures and photophysical properties have been investigated in detail.
We have recently reported a strongly
luminescent osmium(VI) nitrido complex [OsVI(N)(NO2-L)(CN)3]− [HNO2-L
= 2-(2-hydroxy-5-nitrophenyl)benzoxazole]. The excited state of this
complex readily activates the strong C–H bonds of alkanes and
arenes (Commun. Chem.
2019, 2, 40). In this work, we attempted to tune the excited-state
properties of this complex by introducing various substituents on
the bidentate L ligand. The series of nitrido complexes were characterized
by IR, UV/vis, 1H NMR, and electrospray ionization mass
spectrometry. The molecular structures of five of the nitrido compounds
have been determined by X-ray crystallography. The photophysical and
electrochemical properties of these complexes have been investigated.
The luminescence of these nitrido complexes in the solid state, in
a CH2Cl2 solution, and in a CH2Cl2 solid matrix at 77 K glassy medium clearly shows that these
emissions are due to 3LML′CT [L ligand to OsN]
phosphorescence. The presence of strongly electron-withdrawing substituents
in these complexes enhances the LML′CT emission. Our result
demonstrates that the excited-state properties of this novel class
of luminescent osmium(VI) nitrido complexes can be fine-tuned by introducing
various substituents on the bidentate L ligand.
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