Monitoring the Substrate-Induced Spin-State Distribution in a Cobalt(II)-Salen Complex by EPR and DFT
Monitoring the Substrate-Induced Spin-State Distribution in a Cobalt(II)-Salen Complex by EPR and DFT
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通过 EPR 和 DFT 监测钴 (II)-Salen 配合物中基质诱导的自旋态分布
DOI：
10.1002/ejic.202101071
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发表时间：
2022
影响因子：
2.3
通讯作者：
Magri G
中科院分区：
文献类型：
--
作者：
Magri G
用CW EPR、脉冲弛豫和密度泛函理论研究了（R，R '）-N，N'-双（3，5-二叔丁基亚水杨基）-1，2-环己二胺Co（II）与不同吡啶基配位后的基态变化.基于溶液的Co（II）络合物具有低自旋（LS）态， （g值为1.96、1.895、3.14）。在吡啶基底物的配位后，所得的结合加合物显示LS '碱基'物质的分布，具有 电子基态（g值为2.008，2.2145，2.46）和高自旋（HS）物质（geff =4.6）。密度泛函理论表明，在底物配位后，LS和HS态之间的能隙显著降低（ΔE<25 kJ mol−1）。 DFT表明LS和HS体系之间的主要几何差异是N2 O2配体骨架的严重起皱。结果显示，自旋分布初步依赖于底物的pKa−H，在大多数情况下，较高的pKa−H底物值有利于HS物种。
Ground state changes of (R,R’)‐N,N’‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexane‐diamino Co(II), following coordination of various pyridyl substrate has been examined by CW EPR, pulsed relaxation measurements and DFT. The solution‐based Co(II) complex possesses a low spin (LS) state (withg‐values of 1.96, 1.895, 3.14). Upon coordination of the pyridyl substrate, the resulting bound adduct reveals a distribution of LS ‘base‐on’ species, possessing a electronic ground state (withg‐values of 2.008, 2.2145, 2.46) and a high spin (HS) species (withgeff=4.6). DFT indicated that the energy gap between the LS and HS state is dramatically lowered (ΔE<25 kJ mol−1) following substrate coordination. DFT suggests the main geometrical difference between the LS and HS systems is the severe puckering of the N2O2ligand backbone. The results revealed a tentative dependency on the pKa−H of the substrates for the spin distribution where, in most cases, the higher pKa−H substrate values favoured the HS species.