In:
European Journal of Inorganic Chemistry, Wiley, Vol. 2008, No. 31 ( 2008-11), p. 4891-4898
Abstract:
Two new spin‐crossover complexes, [FeL1(phpy) 2 ] ( 1 ) and [FeL2(phpy) 2 ](phpy) ( 2 ), with L1 and L2 being tetradentate N 2 O 2 2– ‐coordinating Schiff‐base‐like ligands {L1 = ( E , E )‐[diethyl 2,2′‐[1,2‐phenylenebis(iminomethylidyne)]bis(3‐oxobutanoato)(2–)‐ N , N ′,O 3 ,O 3 ′], L2 = [(3,3′)‐[1,2‐phenylenebis(iminomethylidyne)] bis(2,4‐pentanedionato)(2–)‐ N , N ′,O 2 ,O 2 ′]and phpy = 4‐phenylpyridine} have been investigated using temperature‐dependent susceptibility and photomagnetic measurements, as well as Mössbauer spectroscopy and X‐ray structure analysis. Compound 1 shows a cooperative spin transition with a thermal hysteresis loop approximately 4 K wide ( T 1/2↓ = 232 K and T 1/2↑ = 236 K). The spin transition of 2 is gradual with T 1/2 ≈ 290 K. Results from X‐ray structure analysis indicate that the cooperative interactions are due to elastic interactions with several intense C–C contacts in the case of 1 . The change of the spin state at the iron centre is accompanied by a change of the O–Fe–O angle, the so‐called bite of the equatorial ligand, from 107° in the high‐spin state to 89° in the low‐spin state. Reflectivity measurements of 1 indicate that the Light‐Induced Excited Spin State Trapping (LIESST) effect occurs at the sample surface at low temperatures. In the bulk solid, photomagnetic properties with a photoexcitation level of 30 % and a T (LIESST) value of 41 K are observed using a SQUID magnetometer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Type of Medium:
Online Resource
ISSN:
1434-1948
,
1099-0682
DOI:
10.1002/ejic.v2008:31
DOI:
10.1002/ejic.200800420
Language:
English
Publisher:
Wiley
Publication Date:
2008
detail.hit.zdb_id:
1475009-0
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