The Original CoII Heteroscorpionates Revisited: On the EPR of Pseudotetrahedral CoII
The Original CoII Heteroscorpionates Revisited: On the EPR of Pseudotetrahedral CoII
复制标题
重温原始 CoII 异蝎子：关于伪四面体 CoII 的 EPR
DOI：
10.1002/ejic.201501356
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发表时间：
2016
影响因子：
2.3
通讯作者：
Baum R
中科院分区：
文献类型：
--
作者：
Baum R
一系列四面体双-bispyrazolylborate配合物的CoII的溶液光谱的检查。这包括重新检查三种稳定衍生物Bp 2Co、Bp 3、5 Me 2Co和（Ph 2Bp）2Co的UV/维斯-NIR，其显示了两个先前未观察到的跃迁，一个由近红外跃迁的分裂引起，另一个由基于配体或电荷转移机制引起;重新评估Δ和B导致与类似络合物更一致的值。一系列复合物的冷冻溶液EPR表明所有复合物都受到不可忽略的负零场分裂的影响。这与以前的粉末测量相反，我们发现只观察到可用跃迁的一个子集，导致母体复合物电子结构的错误分配。基于这组密切相关的配合物的EPR，我们提出了一个建议，即59 Co超精细耦合实际上是MS = ± 3/2基态（D< 0）的指示，而超精细耦合起源于沿λ的名义上禁止的ΔMS= 3跃迁。
An examination of the solution spectroscopy of a series of tetrahedral bis‐bispyrazolylborate complexes of CoIIis presented. This includes a re‐examination of the UV/Vis‐NIR of the three stable derivatives, Bp2Co, Bp3,5Me2Co and (Ph2Bp)2Co, which showed two transitions previously unobserved, one arising from splitting of the near‐infraredd‐dtransition and one arising from a ligand‐based or charge‐transfer mechanism; a reevaluation of Δ and B led to values more in line with similar complexes. Frozen solution EPR of the series of complexes suggests all are under the influence of a non‐negligible, negative zero‐field splitting. This is in contrast to previous powder measurements, which we show observed only a subset of the available transitions, leading to a mis‐assignment of the parent complex's electronic structure. We present a proposal, based on the EPR of this closely related set of complexes, that the59Co hyperfine coupling that is only sometimes observed in the EPR of pseudotetrahedral CoIIat X‐band is in fact indicative of anMS= ± 3/2 ground level (D< 0), with the hyperfine coupling originating in the nominally forbidden ΔMS= 3 transition alongg∥.