Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago , P.O. Box 56, Dunedin 9054, New Zealand.
Inorg Chem. 2013 Oct 7;52(19):11185-99. doi: 10.1021/ic4014416. Epub 2013 Sep 20.
Seven new dinuclear iron(II) complexes of the general formula Fe(II)2(PMRT)24·solvent, where PMRT is a 4-substituted-3,5-bis{[(2-pyridylmethyl)-amino]methyl}-4H-1,2,4-triazole, have been prepared in order to investigate the substituent effect on the spin crossover event. Variable temperature magnetic susceptibility and (57)Fe Mössbauer spectroscopy studies show that two of the complexes, Fe(II)2(PMPT)24·H2O (N(4) substituent is pyrrolyl) and Fe(II)2(PM(Ph)AT)24 (N(4) is N,N-diphenylamine), are stabilized in the [HS-HS] state between 300 and 2 K with weak antiferromagnetic interactions between the iron(II) centers. Five of the complexes showed gradual half spin crossover, from [HS-HS] to [HS-LS], with the following T(1/2) (K) values: 234 for Fe(II)2(PMibT)24·3H2O (N(4) is isobutyl), 147 for Fe(II)2(PMBzT)24 (N(4) is benzyl), 133 for Fe(II)2(PM(CF3)PhT)24·DMF·H2O (N(4) is 3,5-bis(trifluoromethyl)phenyl), 187 for Fe(II)2(PMPhT)24 (N(4) is phenyl), and 224 for Fe(II)2(PMC16T)24 (N(4) is hexadecyl). Structure determinations carried out for three complexes, Fe(II)2(PMPT)24·4DMF, Fe(II)2(PMBzT)24·CH3CN, and Fe(II)2(PM(Ph)AT)24·solvent, revealed that in all three complexes both iron(II) centers are stabilized in the high spin state at 90 K. A general and reliable 4-step route to PMRT ligands is also detailed.
为了研究取代基效应对自旋交叉事件的影响，我们制备了七个通式为Fe(II)2(PMRT)24·溶剂的双核铁(II)配合物，其中 PMRT 是 4-取代-3,5-双{[(2-吡啶甲基)-氨基]甲基}-4H-1,2,4-三唑。变温磁化率和(57)Fe Mössbauer 光谱研究表明，两个配合物Fe(II)2(PMPT)24·H2O（N(4)取代基为吡咯基）和Fe(II)2(PM(Ph)AT)24（N(4)为 N,N-二苯基胺）在 300 和 2 K 之间稳定在[HS-HS]态，铁(II)中心之间存在弱反铁磁相互作用。五个配合物表现出逐渐的半自旋交叉，从[HS-HS]到[HS-LS]，以下是 T(1/2)（K）值：Fe(II)2(PMibT)24·3H2O（N(4)为异丁基）为 234，Fe(II)2(PMBzT)24（N(4)为苄基）为 147，Fe(II)2(PM(CF3)PhT)24·DMF·H2O（N(4)为 3,5-双（三氟甲基）苯基）为 133，Fe(II)2(PMPhT)24（N(4)为苯基）为 187，Fe(II)2(PMC16T)24（N(4)为十六烷基）为 224。对三个配合物Fe(II)2(PMPT)24·4DMF、Fe(II)2(PMBzT)24·CH3CN 和Fe(II)2(PM(Ph)AT)24·溶剂进行的结构测定表明，在所有三个配合物中，两个铁(II)中心在 90 K 时都稳定在高自旋态。还详细介绍了一种通用且可靠的 PMRT 配体的 4 步路线。
