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Title: Ligand-assisted photochemical reaction of metalloporphyrins. Photodissociation of carbon-indium bond in ethylindium (III) tetraphenylporphyrin with the aid of axial pyridine

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100301a018· OSTI ID:5614432

Ethylindium (III) tetraphenylporphyrin, C/sub 2/H/sub 5/In/sup III/TPP, undergoes photodissociation of the carbon-indium bond in the excited triplet state originating from the porphyrin ligand. The quantum yield, Phi, for the photodecomposition of C/sub 2/H/sub 5/In/sup III/TPP in benzene increases with an increase in pyridine concentration: Phi = 0.046 in the absence of pyridine and Phi = 0.3 at an infinite concentration of pyridine. From the quantum yield measurements and laser photolysis studies, it is concluded that the excited triplet states, /sup 3/C/sub 2/H/sub 5/In/sup III/TPP(Py)*, are in equilibrium:/sup 3/C/sub 2/H/sub 5/In/sup III/TPP* + Py ..cap alpha.. /sup 3/C/sub 2/H/sub 5/In/sup III/TPP(Py)*, where Py is a pyridine molecule. The equilibrium constant is determined as 6.45 X 10/sup 2/ M/sup -1/ at 20/sup 0/C. The increase in the quantum yield for the photodecomposition of C/sub 2/H/sub 5/In/sup III/TPP in the presence of pyridine is interpreted in terms of the facile dissociation of the carbon-indium bond in /sup 3/C/sub 2/H/sub 5/In/sup III/TPP(Py)* assisted by the axial pyridine.

Research Organization:
Institute of Physical and Chemical Research, Saitama, Japan
OSTI ID:
5614432
Journal Information:
J. Phys. Chem.; (United States), Vol. 91:17
Country of Publication:
United States
Language:
English