Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials
Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials
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DOI：
10.1021/acs.inorgchem.9b00843
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发表时间：
2019-08-05
影响因子：
4.6
通讯作者：
Kulmaczewski, Rafal
中科院分区：
文献类型：
--
作者：
Halcrow, Malcolm A.;Berdiell, Izar Capel;Kulmaczewski, Rafal
本文研究了43个二吡唑基吡啶铁（II）系列SCO化合物在固态下的自旋交叉（SCO）中点温度（T-1/2）的构效关系。在固态和溶液中的T-1/2之间的差异[Δ T（latt）]被提出作为晶格对转变温度的贡献的量度。SCO温度和SCO过程中配位球重排的幅度之间的负线性相关性在同构或近同构的化合物子集中是明显的;也就是说，SCO过程中分子结构的较大变化稳定了材料的高自旋状态。当Δ T（latt）而不是原始T-1/2值被认为是SCO温度的量度时，通常获得改进的相关性。不同的晶格类型表现出不同的倾向，以稳定它们所包含的分子的高自旋或低自旋状态，这与在每种情况下最影响Δ T（latt）的结构变化相关。这些关系大多不受化合物中SCO协同性或任何晶体相变的影响。每个子集中的一种或两种材料在这些相关性中的一些或全部中是异常值，然而，在某些情况下，这可以归因于它们的配体几何形状的微小差异或SCO期间的不寻常相行为。作为本研究的一部分，还对[Fe（3-bpp）（2）][NCS]（2）中心点nH（2）O [3-bpp = bis（1H-吡唑-3-基）吡啶; n = 0或2]的结构化学进行了重新研究。
Structure-function relationships relating the spin-crossover (SCO) midpoint temperature (T-1/2) in the solid state are surveyed for 43 members of the iron(II) dipyrazolylpyridine family of SCO compounds. The difference between T-1/2 in the solid state and in solution [Delta T(latt)] is proposed as a measure of the lattice contribution to the transition temperature. Negative linear correlations between the SCO temperature and the magnitude of the rearrangement of the coordination sphere during SCO are evident among isostructural or near-isostructural subsets of compounds; that is, a larger change in the molecular structure during SCO stabilizes the high-spin state of a material. Improved correlations are often obtained when Delta T(latt), rather than the raw T-1/2 value, is considered as the measure of the SCO temperature. Different lattice types show different tendencies to stabilize the high-spin or low-spin state of the molecules they contain, which correlates with the structural changes that most influence Delta T(latt) in each case. These relationships are mostly unaffected by the SCO cooperativity in the compounds or by the involvement of any crystallographic phase changes. One or two materials within each subset are outliers in some or all of these correlations, however, which, in some cases, can be attributed to small differences in their ligand geometry or unusual phase behavior during SCO. A reinvestigation of the structural chemistry of [Fe(3-bpp)(2)][NCS](2)center dot nH(2)O [3-bpp = bis(1H-pyrazol-3-yl)pyridine; n = 0 or 2], undertaken as part of this study, is also presented.