Thermal and light-induced spin crossover in iron(II) complexes with monodentate tetrazole ligands carrying long alkyl chains in the 1-position
✍ Scribed by Th. Buchen; P. Gütlich
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 463 KB
- Volume
- 220
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
The complexcompounds Fe(otz)6z (I), [Fe(dotz)el(BF.& (II) and [Fe(odetz)61(BF& (III) (otz=l+octyltetrazole, dotz =I-ndodecyl-tetrazole, odetz = I-n-octadecyl-tetrazole) with monodentate tetrazole ligands carryiq long alkyl chains in the l-position exhibit thermal high-spin (HS, $Ts) elow-spin (LS, 'A, ) transitions below 250 K. All of them show a gradual transition behaviour witb transition temperatures Tilz(~=0.5) of 148 K for I, 120 K for II and 152 K for III.
Compound II shows a residual paramagnetism at low temperatures, while the transitions in I and III are complete. The LIESST effect (lightinduced excited spin state trapping) can be performed with all complexes. The HS+LS relaxation after LIESST was followed by optical spectroscopy on compound I which was pressed to a translucent tablet. The relaxation of the metastable LIESST state deviates strongly from fust-order kinetics due to inhomogeneities in the material.