Photochemical reactions of alkylgallium(III) complexes of tetraphenyl porphyrin dianion (TPP) have been monitored by 1H NMR spectroscopy. Red-purple (TPP)GaIII(cyclopentylmethyl)·C6H5CH3, C57H47N4Ga, crystallizes in triclinic space group P1 with a=10.877(3), b=11.389(2), c=18.786(3) Å, α=81.02(2),β=11.389(2), γ=74.36(2)° at 130 K with Z=2. Refinement of 477 parameters and 4616 reflections yielded R=0.069, Rw=0.072. The structure shows that the gallium ion is five-coordinate with the gallium 0.58 Å out of the N4 plane. The GaC bond distance is 1.992(6) Å and the GaN distances span a narrow range from 2.095(4) to 2.110(3) Å. Photolysis of (TPP)GaIII((CH2)4CHCH2) in benzene solution results in isomerization to form (TPP)GaIII(CH2CH(CH2)4) as a result of homolysis of the GaC bond and cyclization of the 5-hexenyl radical. In the presence of dioxygen photolysis of (TPP)GaIIIC2H5 produces (TPP)GaIII(OOC2H5) and photolysis of (TPP)GapIII((CH2)4CHCH2) yields TPPGapIII(OO(CH2)4CHCH2). In the latter case no isomerization (cyclization) to form TPPGaIII((CH2CH(CH2)4) occurs because the 5-hexenyl radical is intercepted by dioxygen before it can cyclize. Nitrosobenzene (a radical trap) also inhibits isomerization (cyclization) of (TPP)GaIII((CH2)4CHCH2).
|Number of pages||7|
|Journal||Inorganica Chimica Acta|
|State||Published - Mar 15 1993|
Bibliographical noteFunding Information:
We thank the National Institutes of Health (GM 26226) for financial support.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry