Department of Chemistry, University of Hawaii, 2545 McCarthy Mall, Honolulu, Hawaii 96822, USA.
Inorg Chem. 2011 Sep 5;50(17):8630-5. doi: 10.1021/ic201184x. Epub 2011 Jul 28.
A synthesis has been developed that allows the isolation of four-coordinate [(tpy)Ni-Br] (1, tpy = terpyridine) in high yield. Complex 1 has been structurally characterized, and the X-ray data reveal a square-planar geometry, unlike the known [(tpy')Ni-I] (tpy' = 4,4',4''-tri-tert-butyl-terpyridine) but similar to [(tpy)Ni-CH(3)]. In the solid-state, EPR spectroscopy indicates, however, that unlike [(tpy)Ni-CH(3)], the electronic structure of 1 is a metal-centered, not a ligand-centered radical. Density functional theory (DFT) analyses support this assignment. The preparation of 1 also facilitated the analysis of the redox potentials of a series of terpyridine nickel derivatives. It was found that the overall ligand sphere (one vs two coordinated terpyridine ligands) plays more of a role in determining the redox potentials of these derivatives than do the formal oxidation states of the nickel ions in the solution phase.
已经开发出一种方法，可以高产率地分离出四配位(tpy)Ni-Br。已经对配合物 1 进行了结构表征，X 射线数据显示其具有平面正方形几何构型，与已知的(tpy')Ni-I不同，但与[(tpy)Ni-CH(3)]相似。然而，在固态中，电子顺磁共振(EPR)光谱表明，与[(tpy)Ni-CH(3)]不同，1 的电子结构是一个以金属为中心的自由基，而不是以配体为中心的自由基。密度泛函理论(DFT)分析支持这一分配。1 的制备还促进了一系列三吡啶镍衍生物的氧化还原电位的分析。结果发现，与镍离子在溶液相中的形式氧化态相比，整体配体球(一个与两个配位的三吡啶配体)在决定这些衍生物的氧化还原电位方面起着更大的作用。
