Spectroscopic Studies and Bonding Model for Nitric Oxide Complexes of Iron Porphyrins

B. B. Wayland, Larry W. Olson

Research output: Contribution to journalArticlepeer-review

316 Scopus citations


FeIIITPPCl reacts reversibly with nitric oxide to form FeTPP(Cl)(NO) which is spectroscopically studied in toluene solution, glass media, and Nujol mulls. This diamagnetic nitric oxide complex is formulated as FenTPP(Cl-)(NO+). In the presence of methanol, FeIIITPPCl reacts with excess nitric oxide to produce Fe II-TPP(NO). This reaction is thought to proceed via the methanolysis of coordinated NO+ in the intermediate FeII-TPP(Cl-)(NO+) complex. FeIITPP(NO) has a doublet ground state with the odd electron in a molecular orbital with Fe (d,z2) and NO (σN) character. FeIITPP(NO) adds nitrogen donors in the sixth coordination position which have epr spectra showing 14N hyperfine from both nitrogen bonded ligands. A second nitric oxide is reversibly coordinated by FeIITPP(NO) to form FeTPP(NO)2, which on the basis of magnetic and spectroscopic properties is formulated as FeIITPP(NO-)(NO+). Two N-O stretching frequencies are observed consistent with linear FeII- NO+ and bent FeIINO- units. Bonding models are presented for the nitric oxide complexes and generalized for related complexes of diatomic molecules.

Original languageEnglish (US)
Pages (from-to)6037-6041
Number of pages5
JournalJournal of the American Chemical Society
Issue number19
StatePublished - Sep 1 1974
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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