Axial alkyl ligand reactivity in five-coordinate gallium(III) porphyrin complexes

Alan L. Balch, Rebecca L. Hart, Sean Parkin

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


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).

Original languageEnglish
Pages (from-to)137-143
Number of pages7
JournalInorganica Chimica Acta
Issue number2
StatePublished - Mar 15 1993

Bibliographical note

Funding 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


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