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Title: Photophysical effects of metal-carbon sigma bonds in ortho-metalated complexes of Ir(III) and Rh(III)

Abstract

Dichloro-bridged dimers of the type (M(L)/sub 2/Cl)/sub 2/, where L is 2-phenylpyridine (ppy) or benzo(h)quinoline (bzq) and M is Rh(III) or Ir(III), have been characterized by /sup 13/C and /sup 1/H NMR spectroscopies and by absorption and emission spectroscopies. The NMR results confirm previous formulations of the complexes as dichloro-bridged ortho-metalated dimers in halocarbon solvents but indicate that they are cleaved to monomeric species of the type M(L)/sub 2/CIS in ligating solvents such as dimethylformamide (S = solvent). The absorption spectra of each of the complexes contain several low-energy bands which are assigned as metal-to-ligand charge-transfer (MLCT) transitions. All four of the dimers emit light following photoexcitation of their glassy solutions at 77 K. Their emission spectra and lifetimes lead to assignments of their emitting states as intraligand for the Rh(III) dimers and MLCT for the Ir(III) dimers. The Ir(III) dimers are also found to emit light following excitation at 295 K in deaerated dichloromethane. No emission is seen from the Rh(III) dimers under these conditions. Comparison of these results with previous results from studies of similar Rh(III) and Ir(III) complexes of 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) indicates that the ortho-metalated ligands are considerably higher than bpy and phen inmore » the spectrochemical series. In addition to raising the energy of ligand field excited states in their complexes, relative to similar bpy and phen species, they induce lower energy charge-transfer transitions. These effects are consistent with the synergistic function of the ortho-metalated ligands as both strong sigma donors and ..pi.. acceptors.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Univ. of California, Santa Barbara
OSTI Identifier:
6064259
DOE Contract Number:  
AT03-78ER70277
Resource Type:
Journal Article
Journal Name:
J. Am. Chem. Soc.; (United States)
Additional Journal Information:
Journal Volume: 106:22
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BIPYRIDINES; PHOTOLYSIS; IRIDIUM CHLORIDES; ORGANOMETALLIC COMPOUNDS; QUINOLINES; RHODIUM CHLORIDES; CARBON 13; EXPERIMENTAL DATA; NMR SPECTRA; PROTONS; AROMATICS; AZAARENES; AZINES; BARYONS; CARBON ISOTOPES; CHEMICAL REACTIONS; CHLORIDES; CHLORINE COMPOUNDS; DATA; DECOMPOSITION; ELEMENTARY PARTICLES; EVEN-ODD NUCLEI; FERMIONS; HADRONS; HALIDES; HALOGEN COMPOUNDS; HETEROCYCLIC COMPOUNDS; INFORMATION; IRIDIUM COMPOUNDS; ISOTOPES; LIGHT NUCLEI; NUCLEI; NUCLEONS; NUMERICAL DATA; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PHOTOCHEMICAL REACTIONS; PYRIDINES; REFRACTORY METAL COMPOUNDS; RHODIUM COMPOUNDS; SPECTRA; STABLE ISOTOPES; TRANSITION ELEMENT COMPOUNDS; 400500* - Photochemistry; 400201 - Chemical & Physicochemical Properties; 400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)

Citation Formats

Sprouse, S, King, K A, Spellane, P J, and Watts, R J. Photophysical effects of metal-carbon sigma bonds in ortho-metalated complexes of Ir(III) and Rh(III). United States: N. p., 1984. Web. doi:10.1021/ja00334a031.
Sprouse, S, King, K A, Spellane, P J, & Watts, R J. Photophysical effects of metal-carbon sigma bonds in ortho-metalated complexes of Ir(III) and Rh(III). United States. doi:10.1021/ja00334a031.
Sprouse, S, King, K A, Spellane, P J, and Watts, R J. Wed . "Photophysical effects of metal-carbon sigma bonds in ortho-metalated complexes of Ir(III) and Rh(III)". United States. doi:10.1021/ja00334a031.
@article{osti_6064259,
title = {Photophysical effects of metal-carbon sigma bonds in ortho-metalated complexes of Ir(III) and Rh(III)},
author = {Sprouse, S and King, K A and Spellane, P J and Watts, R J},
abstractNote = {Dichloro-bridged dimers of the type (M(L)/sub 2/Cl)/sub 2/, where L is 2-phenylpyridine (ppy) or benzo(h)quinoline (bzq) and M is Rh(III) or Ir(III), have been characterized by /sup 13/C and /sup 1/H NMR spectroscopies and by absorption and emission spectroscopies. The NMR results confirm previous formulations of the complexes as dichloro-bridged ortho-metalated dimers in halocarbon solvents but indicate that they are cleaved to monomeric species of the type M(L)/sub 2/CIS in ligating solvents such as dimethylformamide (S = solvent). The absorption spectra of each of the complexes contain several low-energy bands which are assigned as metal-to-ligand charge-transfer (MLCT) transitions. All four of the dimers emit light following photoexcitation of their glassy solutions at 77 K. Their emission spectra and lifetimes lead to assignments of their emitting states as intraligand for the Rh(III) dimers and MLCT for the Ir(III) dimers. The Ir(III) dimers are also found to emit light following excitation at 295 K in deaerated dichloromethane. No emission is seen from the Rh(III) dimers under these conditions. Comparison of these results with previous results from studies of similar Rh(III) and Ir(III) complexes of 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) indicates that the ortho-metalated ligands are considerably higher than bpy and phen in the spectrochemical series. In addition to raising the energy of ligand field excited states in their complexes, relative to similar bpy and phen species, they induce lower energy charge-transfer transitions. These effects are consistent with the synergistic function of the ortho-metalated ligands as both strong sigma donors and ..pi.. acceptors.},
doi = {10.1021/ja00334a031},
journal = {J. Am. Chem. Soc.; (United States)},
number = ,
volume = 106:22,
place = {United States},
year = {1984},
month = {10}
}