Electronic structure and magnetic properties of a synthetic molecular oxygen carrier: Spin-only triplet behavior for divalent iron(II)
✍ Scribed by W.M. Reif; H. Wong; J.E. Baldwin; J. Huff
- Book ID
- 104138347
- Publisher
- Elsevier Science
- Year
- 1977
- Tongue
- English
- Weight
- 601 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0020-1693
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✦ Synopsis
The magnetic susceptibility of a four coordinate, approximately square planar iron complex of a substituted octaaza [14] annulene of known structure has been studied over the range 1.6 to 300 K. The compound contains an FeN, chromophore and exhibits essentially spin-only magnetic behavior (uett = 2.94 up at 300 K) to as low as 25 K. Below this temperature zero-field splitting is evident, D N 14 cm-', with the effective moment decreasing to 1.34 up at 1.6 K. Zero-field Mossbauer spectra have been measured over the range 3004.2 K and this system as well as another less hindered analogue are found to have the largest quadrupole interactions ("4 mmlsec) yet reported for triplet iron complexes. The Mossbauer spectra also suggest temperature dependence of the recoil free fraction (Goldanskii-Karyagin effect). The large quadrupole effect is consistent with either a 3B or 3E ground term (based on 3T2a of 0,) wit h negligible reduction of the electric field gradient by covalency effects. A reevaluation of the current use of in distinguishing spin-triplet is made.