A Novel Bis(trans-thiocyanate)iron(II) Spin-Transition Molecular Material with Bidentate Triaryltriazole Ligands and Its Bis(cis-thiocyanate)iron(II) High-Spin Isomer
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- 作者：Dunru Zhu ; Yan Xu ; Zhi Yu ; Zijian Guo ; Hai Sang ; Tao Liu ; and Xiaozeng You
- 刊名：Chemistry of Materials
- 出版年：2002
- 出版时间：February 2002
- 年：2002
- 卷：14
- 期：2
- 页码：838 - 843
- 全文大小：96K
- 年卷期：v.14,no.2(February 2002)
- ISSN：1520-5002
文摘
Two novel complexes trans-[Fe(MBPT)2(NCS)2] (1) and cis-[Fe(mMBPT)2(NCS)2] (2) havebeen synthesized and their structure characterized at 293 K by single-crystal X-raycrystallography [MBPT (or mMBPT) = 4-p(or m)-methylphenyl-3,5-bis(pyridin-2-yl)-1,2,4-triazole]. Complexes 1 and 2 are isomers, and 1 crystallizes in the triclinic space group P
with Z = 1, a = 9.120(3) Å, b = 9.2563(18) Å, c = 11.576(2) Å, 
= 76.256(15)
, 
= 76.405(18), 
= 84.983(19), and V = 922.1(4) Å3 in contrast to 2 in the monoclinic space groupC2/c with Z = 4, a = 21.851(3) Å, b = 13.4113(15) Å, c = 16.859(3) Å, = 128.153(9), andV = 3885.0(9) Å3. Both complexes have a similar pseudo-octahedral [FeN6] core with theNCS- groups in the trans arrangement in 1 but cis in 2. Variable-temperature magneticsusceptibility and IR spectral measurements reveal that 1 shows an abrupt high-spin 
low-spin (HS LS) transition centered at T1/2 around 231 K, in contrast to 2 staying in ahigh-spin state in the observed temperature range of 75-300 K. The extended X-rayabsorption fine structures (EXAFS) spectra confirm that the average Fe-N distance for theHS state in 1 is 
0.2 Å longer than that of the LS state. Complex 1 represents the firstspin-crossover iron(II) complex with triaryltriazole and trans-thiocyanate ligands.
with Z = 1, a = 9.120(3) Å, b = 9.2563(18) Å, c = 11.576(2) Å, = 76.256(15), = 76.405(18), = 84.983(19), and V = 922.1(4) Å3 in contrast to 2 in the monoclinic space groupC2/c with Z = 4, a = 21.851(3) Å, b = 13.4113(15) Å, c = 16.859(3) Å, = 128.153(9), andV = 3885.0(9) Å3. Both complexes have a similar pseudo-octahedral [FeN6] core with theNCS- groups in the trans arrangement in 1 but cis in 2. Variable-temperature magneticsusceptibility and IR spectral measurements reveal that 1 shows an abrupt high-spin low-spin (HS LS) transition centered at T1/2 around 231 K, in contrast to 2 staying in ahigh-spin state in the observed temperature range of 75-300 K. The extended X-rayabsorption fine structures (EXAFS) spectra confirm that the average Fe-N distance for theHS state in 1 is 0.2 Å longer than that of the LS state. Complex 1 represents the firstspin-crossover iron(II) complex with triaryltriazole and trans-thiocyanate ligands.