Synthesis, Proton NMR Spectroscopy, and Structural Characterization of Binuclear Ruthenium Porphyrin Dimers

James P. Coliman*, Craig E. Barnes, Paul N. Swepston, James A. Ibers

*Corresponding author for this work

Research output: Contribution to journalArticle

176 Scopus citations

Abstract

The binuclear Ru(II) porphyrin dimers (Ru(OEP))2and (Ru(TPP))2(OEP = 2,3,7,8,12,13,17,18-octaethylporphyrinato; TPP = 5,10,15,20-tetraphenylporphyrinato) have been synthesized by the vacuum pyrolysis of the mononuclear bis(pyridine) complexes Ru(OEP)(py)2and Ru(TPP)(py)2(py = pyridine). A detailed analysis of the paramagnetic shifts observed in the 1H NMR spectra is presented, and a new model for referencing dipolar shifts in a dimeric porphyrin structure type is described. The calculated contact shifts exhibit π symmetry and indicate that the dominant mode of spin transfer into the porphyrin ring is derived from P 3e(π) → Ru charge transfer. In addition, the crystal structure of the OEP dimer is reported. (Ru(OEP))2crystallizes as the dipentane solvate in space group C2h 6-C2/c with Z = 8 in a unit cell of dimensions a = 27.989 (11) Å, b = 27.255 (12) Å, c = 17.737 (8) Å, and β = 102.50 (2)°. The final agreement indices, based on 767 variables and 9806 unique intensities collected at -103 °C on an automatic diffractometer, are R(F2) = 0.066 and Rw(F2) = 0.124. The conventional R index on F for 7304 reflections having F2> 3σ (Fo 2) is 0.042. The distance between the Ru atoms is 2.408 (1) Å and the mean Ru-N distance is 2.050 (5) Å. Each Ru atom is situated 0.30 Å out of a plane defined by four coordinating N atoms in the direction of the other Ru atom. The two porphyrin macrocycles are twisted 23.8 (1)° with respect to each other. Both porphyrinato cores have domed-type distortions with average deviations from the least-squares planes of 0.07 and 0.10 Å and maximum deviations of 0.19 and 0.24Å, respectively. The X-ray and NMR results are consistent with a qualitative MO diagram that suggests a formal Ru-Ru bond order of 2.

Original languageEnglish (US)
Pages (from-to)3500-3510
Number of pages11
JournalJournal of the American Chemical Society
Volume106
Issue number12
DOIs
StatePublished - Apr 1984

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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